Managing Vertebrate Pests: Foxes - PestSmart

Bureau of Resource Sciences

Managing Vertebrate Pests:

Foxes

Glen Saunders, Brian Coman,

Jack Kinnear and Mike Braysher

Australian Government Publishing Service

C a n b e r r a

© Commonwealth of Austral ia 1995

ISBN 0 644 29240 7 (set)

ISBN 0 644 (This publication)

This work is copyright. Apart from any use as permitted under the Copyright Act 1968,

no part may be reproduced by any process without prior writ ten permission from the

Australian Government Publishing Service. Requests and inquiries concerning reproduction

and rights should be addressed to the Manager, Commonwealth Information Services,

Austral ian Government Publishing Service, GPO Box 84, Canberra ACT 2601.

Scientif ic edit ing by Mary Bomford.

Cover and publication design by Bob Georgeson, Bureau of Resource Sciences Design

S t u d i o .

Credits for cover photograph. Main: C. Marks, DCNR, Victoria. Insert : G. Chapman,

CSIRO.

Typesett ing and diagrams by Henryk Dekker.

The Bureau of Resource Sciences is a professionally independent Bureau established in

October 1992 in the Department of Primary Industries and Energy. I ts role is to

enhance the sustainable development of Austral ia’s agricultural, mineral, petroleum,

forestry and fisheries resources and their industries by providing scientif ic and

technical advice to government, industry and the community.

Author aff i l iat ions: Glen Saunders, NSW Agriculture; Jack Kinnear, Department of

Conservation and Land Management, Western Australia; Brian Coman, Vernox Pest Management;

Mike Braysher, Bureau of Resource Sciences.

Publication to be cited as:

Saunders, G., Coman, B., Kinnear, J . and Braysher, M. (1995) Managing Vertebrate

Pests: Foxes. Austral ian Government Publishing Service, Canberra.

Printed for AGPS by Paragon Printers, Wollongong Street, Fyshwick ACT 2609

Bureau of Resource Sciences iii

FOREWORD

This publication, which is one in a series,provides land managers with ‘best practice’national guidelines for managing the agri-cultural and environmental damage causedby foxes. Others in the series includeguidelines for managing feral horses,rabbits, feral goats, feral pigs and r odents.The publication was developed and fundedby the Vertebrate Pest Pr ogram in theBureau of Resource Sciences. Pr oductionof the fox guidelines was aided by financialassistance from the Australian Natur eConservation Agency’s Feral Pests Pr ogram.

To ensure that the guidelines ar e widelyaccepted as the basis for fox management,comment has been sought fr om state,territory and Commonwealth gover nmentagriculture, environmental and r esourcemanagement agencies. Comments wer e alsosought from land managers and communityand other or ganisations, including theAustralian Conservation Foundation, theNational Farmers’ Federation, the NationalConsultative Committee on Animal W elfare,the Anangu Pitjantjatjara Aboriginal LandCouncil and the Norther n Land Council. TheStanding Committee on Agricultur e andResource Management has endorsed theapproach to managing fox damage set outin these guidelines.

Foxes are widely per ceived by the widercommunity and by scientists and conser -vationists as a thr eat to native species due

to their r ole as pr edators. Despite thisperception, there is little r eliable informationon the ef fects of fox pr edation on pr eypopulations or of the ef fect of fox contr olon the r ecovery of pr ey species. Theexception is in Western Australia, wheresome field experiments have shown that foxcontrol can lead to the r ecovery of nativespecies, including r ock-wallabies, bettongsand numbats. Foxes may also detrimentallyaffect native species such as bir ds of pr eyand large reptiles by competing with themfor food, but such impacts ar e speculativeas no studies have been conducted.

Less is known about the agriculturalimpact of foxes, although ther e is increasingevidence that foxes may inflict sever e levelsof lamb pr edation which were previouslyunrecognised. Foxes ar e also implicated indeaths and injuries to calves and dairy cattle,although this impact has not beenquantified. There is also a small risk thatfoxes could have a r ole in the spr ead ofexotic diseases, such as rabies, should suchdiseases enter Australia.

There are diverse views about foxmanagement. While economists wouldargue that spending on pest contr ol shouldbe justified in ter ms of the economic r eturnson such investments, this is clearly dif ficultwhen the impacts of foxes for both con -servation and agricultural values, and the

iv Managing Vertebrate Pests: Foxes

Peter O’BrienActing Executive DirectorBureau of Resource Sciences

responses of pr ey populations to foxcontrol, are poorly quantified. Those withan interest in conservation place a highvalue on the pr otection of native speciesand often consider fox contr ol to be apriority for endanger ed species pr otection.People interested in hunting foxes forcommercial use or r ecreation want to r etainfoxes as a r esource. The crash of fox peltprices resulting from the actions of the anti-hunting lobby in Eur ope has r educedinterest in fox harvesting in r ecent years.People concerned with animal welfar e hopeto ensure that fox contr ol or harvesting isconducted using humane techniques. Theauthors have attempted to take all thesedivergent views and values into account incompiling the guidelines.

The principles underlying the strategicmanagement of vertebrate pests have beendescribed in Managing Vertebrate Pests:Principles and Strategies (Braysher 1993).The emphasis is on the management of pestdamage rather than on simply r educing pestdensity. The guidelines r ecommend thatwherever practical, management shouldconcentrate on achieving clearly definedconservation or agricultural pr oductionobjectives.

These guidelines will help land managersreduce damage to agricultur e and nativefauna caused by foxes thr ough the use ofscientifically-based management that ishumane, cost-ef fective and integrated withecologically sustainable land management.

CONTENTS

FOREWORD iiiACKNOWLEDGMENTS viiiACRONYMS AND ABBREVIATIONS ixGLOSSARY xSUMMARY 1INTRODUCTION 7

1. HISTORY 11Summary 111.1 Europe and America 111.2 Australia 11

2. DISTRIBUTION AND BIOLOGY 15Summary 152.1 Distribution and abundance 152.2 Biology 18

3. ECONOMIC AND ENVIRONMENTAL IMPACTS 27Summary 273.1 Environmental impact 283.2 Economic impact 373.3 Resource value and use 41

4. RABIES AND FOXES 43Summary 434.1 The disease 434.2 Management techniques for rabies contr ol 454.3 Implications for Australia 464.4 Implications for fox management 47

5. COMMUNITY ATTITUDES AFFECTING FOX MANAGEMENT 48Summary 485.1 Perceptions of the fox 485.2 Sport hunting 485.3 Animal welfare 495.4 Implications of fox harvesting for damage contr ol 54

6. PAST AND CURRENT MANAGEMENT 56Summary 566.1 History 566.2 Legislation and coordination of management pr ograms 57

7. TECHNIQUES TO MEASURE AND CONTROL FOX IMPACT AND ABUNDANCE 63Summary 637.1 Introduction 637.2 Assessing impact 647.3 Measuring fox abundance 687.4 Use of fox impact and density measur ements 707.5 Control techniques 72

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8. STRATEGIC MANAGEMENT AT THE LOCAL AND REGIONAL LEVEL 88Summary 888.1 Economic frameworks 898.2 Strategic approach 898.3 Problem definition 898.4 Management plan 908.5 Implementation 948.6 Monitoring and evaluation 948.7 Hypothetical example of strategic management at local and

regional level — conservation 958.8 Hypothetical example of strategic management at local and

regional level — agricultur e 98

9. IMPLEMENTING MANAGEMENT OF FOX DAMAGE 101Summary 1019.1 Introduction 1019.2 Role of gover nment and landholders 1019.3 Use of community gr oups 1029.4 Community awareness 104

10. DEFICIENCIES IN CURRENT KNOWLEDGE AND APPROACHES 106Summary 10610.1 Introduction 10610.2 Specific deficiencies 107

REFERENCES 112

APPENDIX A Native species believed to be at risk fr om fox pr edation 126

APPENDIX B Technique for the manufactur e and use of cyanide capsules 127

APPENDIX C Instructions for the use of FOXOF F® baits 128

APPENDIX D Criteria for eradication 132

APPENDIX E Best practice extension in pest management 133

APPENDIX F Economic framework for feral pig management 135

INDEX 139

FIGURESFigure 1 Strategic approach to managing fox damage. 8Figure 2 Spread of the r ed fox in Australia. 12Figure 3 Interrelationship between fox and rabbit populations. 13Figure 4 Relative distribution of foxes and rabbits in Australia. 14Figure 5 Present-day world distribution of the r ed fox. 16Figure 6 Variations with time of rabbit and pr edator (cat and fox) numbers

in central-western New South Wales. 20Figure 7 Variation in fox and feral cat numbers in r elation to changes

in rabbit numbers in south-wester n Western Australia. 21

vi Managing Vertebrate Pests: Foxes

Figure 8 Predator removal experiment conducted over eight years inWestern Australia for five colonies of r ock-wallabies. 29

Figure 9 The relative abundance of Rothschild’s r ock-wallaby, beforeand after fox contr ol in the Dampier Ar chipelago. 30

Figure 10 Percentage capture rate of bettongs after five years of fox contr olin Tutanning Nature Reserve.31

Figure 11 Numbat sightings in Dryandra State For est between 1979 and 1992. 32Figure 12 The quantity of 1080 and the number of baits used for fox contr ol

in New South Wales between 1980 and 1993. 55Figure 13 Bounty payments in Western Australia. 57Figure 14 Determining the cause of lamb death. 66Figure 15 Example of a simple map of four hypothetical pr operties showing

the key factors that landholders should r ecord and use to planfox management. 71

TABLESTable 1 Density estimates of Australian fox populations. 17Table 2 Comparison of mean home range estimates for foxes in dif ferent habitats. 22Table 3 Percentage occurrence and percentage volume of major food items

identified in the stomachs of foxes. 23Table 4 Quantity and value of wild r ed fox pelts supplied during 1982–83

from the major exporting countries involved. 41Table 5 Number and value of raw fox pelts exported fr om Australia. 41Table 6 Number of 35 milligram strychnine baits pr epared for fox contr ol in

South Australia in 1984–85 to 1990–91. 61Table 7 State and territory legislative r equirements for fox poisoning. 75

Bureau of Resource Sciences vii

The Vertebrate Pests Committee’s WorkingGroup, which is overseeing the pr eparationof the guidelines — Peter Allen, RogerO’Dwyer, John Hicks, Don Pfitzner , KevinHeinrich, Neil Hogstrom and John Auty —provided valuable input and comments.

Special acknowledgment is given to thefollowing people who made helpfulcomments on the draft manuscript: PeterAlexander, Peter Bir d, Peter Catling, T erryKorn, Geoff Lundie-Jenkins, Clive Marks,Nicky Marlow, Nick Mooney, GlenysOogjes, Jef f Short, Linton Staples, JimThompson and Paul de T orres.

Several individuals from the Bur eau ofResource Sciences deserve mention. QuentinHart and Hazel Small helped edit themanuscript and figur es. Deborah McLeodassisted with pr eparation of the manuscript.Mary Bomford provided extensive scientificand other editorial comment. Quentin Hartand Mary Bomfor d organised the finalcollation and publication.

The draft manuscript was cir culated to thefollowing organisations for comment:

• Commonwealth Department of PrimaryIndustries and Energy

• Standing Committee on Agricultur e andResource Management

• Australia and New ZealandEnvironment and Conservation Council– Standing Committee on

Conservation– Standing Committee on the

Environment• Land and Water Research and

Development Corporation• Meat Research Corporation• Rural Industries Research and

Development Corporation• International Wool Secretariat• Australian Conservation Foundation• National Consultative Committee on

Animal Welfare• National Farmers’ Federation• Murray Darling Basin Commission• Australian Veterinary Association• Anangu Pitjantjatjara Land Council

We wish to thank all these gr oups for theircontributions. Many other people, toonumerous to acknowledge individually, alsogave us the benefit of their experiences bycommenting on drafts of the manuscript. TheAustralian Nature Conservation Agencyprovided financial assistance.

viii Managing Vertebrate Pests: Foxes

ACKNOWLEDGMENTS

ANCA Australian NatureConservation Agency

ANZFAS Australian and New ZealandFederation of Animal Societies

APB Agriculture Protection Board(Western Australia)

APCC Animal and Plant Contr olCommission (South Australia)

AUSVETPLAN Australian VeterinaryEmergency Plan

AVA Australian VeterinaryAssociation

BRS Bureau of Resour ce SciencesCALM Department of Conservation

and Land Management(Western Australia)

CCNT Conservation Commission ofthe Northern Territory(now Parks & W ildlifeCommission of the Norther nTerritory)

CRC Cooperative Research Centrefor Biological Contr ol ofVertebrate Pest Populations

CSIRO Commonwealth Scientific andIndustrial ResearchOrganisation

DCNR Department of Conservationand Natural Resources(Victoria)(now Department of theNatural Resources and theEnvironment)

DEST Department of Envir onment,Sport and Territories

ERIN Environmental ResourcesInformation Network

ESAC Endangered Species AdvisoryCommittee

FPP Feral Pests Program (ANCA)GIS Geographic information

systemHCAV Hunt Clubs Association of

VictoriaHIPD Hunting indicator of

population densityLandcare Commonwealth Landcare

Program

LandCare Victorian Landcare ProgramMAFF Ministry of Agriculture,

Fisheries and Food (UnitedKingdom)

NLP National Landcare Program(now part of the NaturalHeritage Trust)

PMIS Pest management infor mationsystem

RLPB Rural Lands Pr otection BoardRSPCA Royal Society for the

Prevention of Cruelty toAnimals

SCARM Standing Committee onAgriculture and Resour ceManagement

VPP Vertebrate Pest Program (BRS)(now National Feral AnimalControl Program)

Bureau of Resource Sciences ix

ACRONYMS AND ABBREVIATIONS

abortifacient: a chemical used to induceabortion

ad hoc measures: specially arranged forthe purpose

anticoagulant: a substance that slows orprevents blood clotting. Anticoagulantsmay be used as poisons to kill pestanimals.

attenuated strains: a weak strain of aninfectious organism

biltong: strips of sun-dried, lean meatbiocontrol/biological control agent: a

living organism (or a virus) used tocontrol the population density ofanother species

brittilised capsule: a capsule for oraldosing of animals that has been madebrittle so it will easily shatter wheneaten but is safe to carry

cadastral information: usually includesproperty boundaries, land tenur e androads

Canidae, canids: the family of animalsthat includes dogs, foxes and wolves

carcinogenic: cancer causingcarrying capacity: the maximum number

of animals that the r esources availablein an area of land can support

chenopod: plant of the familyChenopodiaceae. In arid ar eas ofAustralia chenopods are mostly salt-tolerant shrubs such as blue bush andsalt bush.

crepuscular: animals active at dawn anddusk

dasyurids: animals in the family ofcarnivorous marsupials Dasyuridae,including quolls, dunnarts,antechinuses, planigales, ningauis andthe Tasmanian devil

diurnal: animals active during the daydystocia: difficult birthendangered species: species in danger

of extinction and whose survival isunlikely if the causal factors leading totheir decline continue to operate

endocrine function: the r elease,distribution and ef fects of hormones inan animal’s body

endoparasite: animals that live insideanother animal’s body, such as tapewor msand the bacteria in the digestive tract

enzootic areas: areas where a diseaseoccurs in wildlife

European rabbit flea: a flea intr oduced toassist the spread of myxomatosis

family group: occupants of a fox territory,usually composed of a monogamousadult pair and their of fspring from theprevious breeding season; a dominantadult pair, subordinate adults andoffspring, or other common combinations

forb: a soft herb-like plant with a non-woody stem, especially a pastur e plantthat is not a grass

geographic information system (GIS):acomputer-based system for displaying,overlaying and analysing geographicinformation such as vegetation, soils,climate, land use and animal distributions

gestation: pregnancyhome range: the area an animal ranges

over during its nor mal daily activitiesimmunosterility: causing an animal to

become sterile by immunising it againstone of the pr oteins or hormonesinvolved in the r eproductive process

index, indices: a measure which iscorrelated with a value but is not anactual estimate of that value. Forexample spotlight counts give an indexof fox numbers but do not give anestimate of total numbers.

intraperitoneal: into the abdominal cavityintubation: to insert a tube intoLD

50: the quantity of poison or lethal dose

that will kill 50% of tr eated animalsmacropods: animals in the Macr opodidae

superfamily which includes kangar oos,wallabies, bettongs, rat kangar oos,potoroos, pademelons and tr eekangaroos

x Managing Vertebrate Pests: Foxes

GLOSSARY

minimum convex polygon: a simplemethod for calculating the ar eaenclosed by an animal’s home range. Itinvolves drawing the smallest possibleconvex polygon around the outermostlocations or sitings of the animal.

monoestrus: become reproductivelyreceptive only once per year

neophobia: fear of new thingsnocturnal: animals active at nightone-shot oats: technique for poisoning

rabbits using 1080 and oats wher ebyonly one in one hundr ed oat grainscontain 1080 poison, suf ficient to kill anadult rabbit

oral delivery: a dose swallowed in foodor drink

parturition: birthpelt: the skin and fur , either raw or dr essedpopulation turnover: the average time it

takes to replace a generationRD50: the concentration of a sensory

irritant which pr oduces a 50% decr easein an animal’s br eathing rate

recombinant virus: a virus which hasbeen modified by artificial geneticmanipulation

relict population: a small isolatedpopulation of a species that was oncemore widespread and abundant

scat: faecessecondary poisoning: intoxication or

death of animals caused by ingestion ofother poisoned animals

spotlight traverse: a fixed line of travelover which animals in a spotlight beamare counted

sylvatic: involving one or mor e wildlifespecies

tarbaby: a technique for killing foxeswhere 1080 poison in gr ease is squirtedinto a fox den. The fox dies fr omingesting the poison gr ease from furand paws.

territory: the area an animal or gr oup ofanimals defends from intruders

tetanic spasms: violent generalisedmuscular contractions with flailinglimbs

transect: a rectangular plot in which datacollection occurs

translocation: moving a species to adifferent place or habitat

ultrasound scanning: use of lowfrequency sound to investigate theinternal structure of an animal withoutsurgery, used for counting foetuses

vectors: organisms or substances that ar evehicles to spread a biocontrol agent ordisease among animals. For example,mosquitoes are vectors of myxomatosis.

vulnerable species: species believedlikely to become endanger ed in thenear future if the causal factors continueto operate

Note: All money values thr oughout theguidelines are in 1993-94 Australian dollars.

Bureau of Resource Sciences xi

xii Managing Vertebrate Pests: Foxes

Bureau of Resour ce Sciences 1

SUMMARY

The introduced European red fox (Vulpesvulpes) is widely distributed thr oughout thesouthern half of Australia in virtually allhabitats, including urban envir onments.Foxes are seen as a major pest speciesthreatening the long-term survival of a rangeof native fauna. The r eview of fox damageundertaken in developing these guidelinesconfirmed this threat, although scientificallyquantified information of fox damage isbased mainly on studies in W esternAustralia. Foxes ar e also an agricultural pestbecause they pr ey on lambs and otherlivestock.

These guidelines contain a compr ehen-sive r eview of the history of foxes inAustralia, their biology, the damage theycause, and past and curr ent management.The attitudes of conservationists, animalwelfare groups, commercial and r ecreationalhunters, and other inter est groups ar eexamined. Management techniques andstrategies for fox contr ol are recommendedand illustrated by case studies. Deficienciesin knowledge, management and legislationare identified.

Why develop national guidelines?

These guidelines for managing the impactof foxes have been developed under theVertebrate Pest Pr ogram (VPP) administeredby the Bur eau of Resour ce Sciences (BRS)which is pr oducing a series of pestmanagement guidelines in cooperation withthe Vertebrate Pests Committee. The majorpests being addressed in the series ar e foxes,feral horses, rabbits, feral goats, feral pigsand rodents.

The purpose of the guidelines is to assistthe development of strategies to r educe thedamage foxes cause to pr oduction andconservation using the most cost-ef fectiveapproaches. Ideally, such strategies ar ebased on r eliable, quantitative infor mationabout the damage caused by the pest, thecost of contr ol measures, and the ef fect of

implementing control on r educing thedamage. We have little r eliable informationof this type for fox management. Indeveloping these guidelines, the authorshave used available infor mation, but landmanagers responsible for fox contr ol willstill have to make assumptions about foximpact and the ef f icacy and cost-effectiveness of contr ol techniques untilmore r eliable infor mation becomesavailable. It is expected that in planning andimplementing fox management, gover nmentland management agencies will closelyinvolve community-based gr oups such asLandcare.

The fox problem

Within 30 years of their initial r elease insouthern Victoria in the 1860s, foxes wer eproclaimed as a pest in some shir es of north-east Victoria. Pest status was based initiallyon livestock pr edation, particularly onnewborn lambs.

Significant predation by foxes onendangered or vulnerable species has longbeen suspected; but only in the last decadehas scientific evidence been pr oduced whichdirectly incriminates the fox as a major causeof population decline in some species. Thebest known example is that of the black-footed rock-wallaby (Petrogale lateralis),living in small, r elict colonies in the wheat-belt of Western Australia. Here, high-levelmanagement of local fox populations usingpoisoned baits r esulted in a substantialincrease in wallaby numbers. These foxremoval experiments have now beenrepeated in other ar eas and for other wildlifespecies. The evidence suggests that in nearlyall cases, the r emoval of foxes r esults notonly in substantial population incr eases buta wider use of the habitat by the particularprey species concer ned. Circumstantialevidence based on fox distribution and faunalabundance consistently indicates that the foxis an important pr edator of some smallerwildlife species.

The findings concer ning fox damage tonative fauna outlined in these guidelines

Managing Vertebrate Pests: Foxes2 Managing Vertebrate Pests: Foxes

highlight the need for conservationagencies in Australia to assess the extentof fox damage in ar eas containing wildlifevulnerable to fox pr edation. Where thedamage is s ignif icant , they shouldimplement fox management using theappropriate technique and strategyoutlined in these guidelines. Furtherdecline or extinction of native fauna mayresult if this course is not followed.

The economic significance of foxes aspredators of livestock is uncertain andsubject to debate. Recent studies of ewefertility using ultrasound scanning forpregnancy and litter -size testing, suggestthat the losses of lambs to pr edators arehigher than earlier studies indicated. It mayexceed 10% and be as high as 30%. In manyinstances however, other factors such asstarvation, mismothering, dif ficult birth andcold weather may be of much gr eatereconomic significance to the sheepindustry. These factors may also incr easethe susceptibility of lambs to pr edation byfoxes.

Losses of other livestock, particularlypoultry, are probably of far less economicsignificance. However, with a marked risein the popularity of specialty stock andhobby farms, which have a wider collectionof poultry and animals susceptible to foxpredation, the cost of such pr edation byfoxes may be significant to individualproducers.

The fox in Australia carries no diseasesof serious economic or public healthsignificance, although recently foxes havebeen found to harbour the hydatid parasite,requiring continued surveillance of thissituation. Controversy still surrounds thepossible role of foxes in Australia as apotential wild reservoir host for the rabiesvirus. In many parts of the norther nhemisphere, the fox is the main r eservoirof this disease and, given the widespr eaddistribution of foxes in Australia, thepossibility of rabies developing as anestablished disease in fox populationscannot be dismissed. Fox density andmovement data from rabies enzootic ar eas

of Eur ope and North America ar ecomparable with those obtained fr omlimited studies in some parts of souther nAustralia. This suggests that conditions ar etheoretically suitable for the disease tobecome established and to persist at leastin southern Australia. Ther e are, however,many strains of the rabies virus overseasand it is not clear which, if any, of thesestrains might be suited to a wild animalrabies cycle in Australia which wouldinvolve foxes as the main r eservoir host.The likelihood of a smuggled animaldeveloping rabies and then infecting a wildfox is low.

There is a close r elationship betweenfox and rabbit numbers. When rabbitpopulat ions crash, due to dr ought,myxomatosis or Rabbit Calicivirus Disease(RCD), there will be a lag period until foxnumbers decline and adjust to the r educedpr ey populat ion. The l ikel ihood ofincreased predation pressure on nativewildlife over this period needs to beconsidered. Rabbit numbers may also beaffected by foxes. Pr eliminary studiessuggest that foxes and feral cats may slowthe recovery of rabbit populations afterthey crash due to dr ought or disease. Thepotential role of foxes in rabbit contr ol andthe impact of foxes on native wildlifefollowing crashes in rabbit populationsneeds to be clarified.

Why do foxes prosper in Australia?

A number of qualities have helped the foxto successfully colonise Australia includingtheir wide dietary range covering small tomedium-sized mammals, bir ds, reptiles andamphibians, insects, carrion, fruit, andhuman refuse. Unquestionably, though, therabbit has been a major factor . Whereverrabbits are common they ar e the staple foodof foxes. The fox also has high r eproductivesuccess. Although litters ar e small, andfemales only br eed once per year , cubsurvival is high and most adults appear tobreed. With the possible exception of mangeand distemper, the fox has few seriousdiseases. It also has few natural enemies.


Many fox deaths ar e human induced. Sever emange and the r eduction of rabbit numbersdue to dr ought and disease have also causedsignificant deaths of foxes in some ar eas.Rural fox density is thought to vary between0.2–7 per squar e kilometre, while they canreach 12 per squar e kilometre in urbanareas.

Development of a strategicmanagement approach

Historically, pest contr ol authorities haveencouraged management of fox damage tolivestock or wildlife in Australia lar gely bythe use of bounty schemes. Althoughpoisoning, shooting and trapping have beenemployed, these wer e usually by individuallandholders.

Traditional forms of bounty paymenthave been shown to be inef fective and mostfox bounty schemes in Australia have nowstopped. The only bounty curr ently in placeis the ‘Foxlotto’ scheme used in V ictoriaalthough this is small scale. Most br oadacrecontrol is thr ough poison baits. At a localfarm level, shooting, particularly nightshooting with spotlights, driving befor e gunsand gassing of br eeding dens is carried out,but the r eduction in fox density is pr obablytemporary.

Research in W estern Australia hasdemonstrated that foxes can be contr olledusing 1080 meat baits without risk to nativecarnivores and omnivor es (for examplequolls, bettongs, bandicoots and smallerdasyurids). While it is conceded thatelements of the W estern Australian faunaare 1080 tolerant thus pr oviding a marginof safety, the extent of this advantage mayhave been over emphasised. The proceduresdeveloped in Western Australia are likelyto be applicable to other parts of Australia,provided that appr opriate risk assessmentresearch is carried out first to deter mine thespecies which ar e at risk fr om 1080poisoning.

The effective management of fox damageover large areas requires greater attention

to planning and coordination ofmanagement. It is r ecommended that ef fortsto manage fox damage over lar ge areasprimarily be coor dinated programs usingpoisoned baits. These may be laid on thesur face or buried depending oncircumstances or legislative r equirements.Community-based schemes such asLandcare can help to achieve this goal.Foxes rapidly r ecolonise after contr ol.Therefore techniques must be appliedregularly or tar geted for long-ter m controlof damage. For example, ther e may be nopoint in poisoning foxes to pr otect lambsat times during the year when no damageis occurring.

Economic frameworks need to bedeveloped to assist land managers assessthe r elative value of alter native foxmanagement strategies. Such frameworksrequire: definition of the economic pr oblem;data on the r elative costs and benefits; andan understanding of why the actions ofindividual land managers may not lead tooptimal levels of fox contr ol and how suchproblems can be addr essed by landmanagers and gover nments.

What is the strategic approach?

The emphasis in these guidelines is noton killing foxes but rather on their ef ficientand strategic management to r educe thedamage they cause to pr oduction andconservation values. Foxes ar e but onefactor in a complex and changingenvironment that includes a highly variableclimate, fluctuating commodity prices,other animal and plant pests, far m stockand the pr ofitability of far ming businesses,and the viability of conservation r eserves.Land managers need to considerinvestment in fox management in thecontext of investment in other ar eas of theland management unit as well as in r elationto their impact on natural and semi-naturalecosystems, and on the biodiversity withinthem.

Achieving a strategic appr oach to themanagement of foxes and other vertebrate

Foxlotto

"Foxlotto" ceased in 1993.

4 Managing Vertebrate Pests: Foxes

pests involves establishing four keycomponents. These are:

Defining the problem — The problem shouldbe defined in ter ms of fox damage and thereduction in fox density r equired to reduceor prevent the damage.

Developing a management plan — Landmanagers must establish clear objectivesin terms of the desir ed production orconservation outcome sought. Options forfox management include local eradication,strategic management, crisis managementand no management. Eradication will rar elybe a feasible objective. Wher e fox controlis shown to be necessary, these guidelinesstrongly recommend sustained, strategicmanagement as the principal managementoption.

Implementing the plan — A local or r egionalapproach to fox management is usuallymost effective. This generally r equirescoordinated action by individual pr opertymanagers and gover nment and otheragencies. Such action limits the extent ofrapid recolonisation where only small-scalefox control is implemented.

Monitoring and evaluating the program —Monitoring has two aspects. Operationalmonitoring assesses the ef ficiency of thecontrol operation. Performance monitoringinvolves gathering information to deter minewhether the strategy is meeting the desir edlong-term production or conservation goal.

The above approach has been adoptedfor developing these national guidelines,and the infor mation in this r eport isdesigned to facilitate the development ofstrategies for managing foxes at the localand regional level.

Community attitudes

In Australia, as elsewher e, the fox isregarded as a killer , a pest, a r oguepossessed of inordinate cunning, acommercial resource, a har mless or evenbeneficial component of the ecosystem, andfinally, an honoured object of the chase.

The community generally has littleknowledge of the biology and damage foxescause in Australia. Those who speak on theneed for fox contr ol often call for eradicationof foxes thr oughout Australia. This is clearlynot achievable. Even with the possiblesuccess of pr esent research intoimmunosterility, continuing control will berequired.

Several of the techniques used to contr olfoxes raise animal welfar e concerns, mostnotably the use of steel-jawed traps.However, the use of steel-jawed traps hasbeen wholly or partly banned in many statesand territories but hunting with dogs,particularly den terriers, continues. Suchhunting is not humane or ef fective, andoften causes suf fering to both hunted andhunter. A leg-snar e device, developedrecently in V ictoria, offers a mor e humanealternative to steel-jawed traps, particularlyin urban and semi-urban ar eas. However,humaneness of the device depends uponfrequent inspection of the snar es and theearly removal of captur ed animals. Theiracceptance will ther efore depend on thedevelopment and enfor cement of minimuminspection standards.

Poisoning with 1080 in buried meat baitsis probably the most humane, ef ficient andselective method of fox contr ol. Strychnine,still registered as a fox poison in some statesand territories, is a much less humane poison.The humaneness of 1080 is a little unclear ,but because foxes ar e highly susceptible tothis poison, especially compar ed to mostpotential non-target animals, it shouldcontinue to be used until a mor e suitablealternative is found. Cyanide is a humanepoison that kills rapidly. Unfortunately, thenon-target impact of this poison is not wellknown and ther e are concerns about humansafety. Further r esearch is r equired on thepossible use of cyanide for fox contr ol.

The future

Current r esearch aimed at immuno-sterilisation of foxes in Australia as anefficient form of biocontr ol should be


supported, although it must be r ecognisedthat this is high-risk, long-ter m research.Managers will need to r ely on availabletechniques for the for eseeable future. Theeffect of fox pr edation on populations of arange of native species (including birds,reptiles and amphibians) in dif ferentecosystems needs to be better quantified.At the moment, much of this work isconcentrated in Western Australia and littledata is available for the r est of the mainland.The relationship between fox densities andimpact on pr ey populations in particularneeds to be quantified.

The predator–prey relationship betweenfoxes and rabbits r equires closer study. Ofparticular importance is the ef fect offluctuating rabbit numbers upon the pr eyrange of foxes, especially any incr easedpressure upon endanger ed or vulnerablewildlife species as the r esult of a suddendrop in rabbit density.

Currently, relatively little is known of foxecology in Australia and ther e is wideregional variation in habitat, behaviour andpopulation dynamics. Studies ar e required,particularly on population densities andmovement across different habitats, so thatland managers can use this infor mation todevelop appropriate management strategies.

Recent evidence suggests that historicalstudies on lamb pr edation in Australia mayhave underestimated the economic lossesdue to foxes. Further studies ar e needed tobetter quantify the losses.

Commonwealth, state and territorygovernments must critically examine theirpresent legislation and strategies r elating tofox management. While mor e evidence isrequired about the extent of fox damage towildlife in parts of Australia other thanWestern Australia, there is suf ficient evidencethat precautionary management of foxes isrequired in areas with uncommon nativespecies susceptible to foxes. These includethe smaller macropods. With the developmentof Landcare, and other similar community-based groups, it is possible to bettercoordinate fox management over lar ge areas.

There is a need for impr oved coordinationbetween agencies and gover nment withinterests and responsibilities for fox contr ol.



INTRODUCTION

These guidelines for managing foxes ar e onein a series developed under the V ertebratePest Program (VPP) of the Bur eau ofResource Sciences in cooperation with theVertebrate Pests Committee of the StandingCommittee on Agricultur e and ResourceManagement (SCARM). Others include theferal horse, rabbit, feral goat, feral pig androdents. The need for a new appr oach tovertebrate pest management is described inManaging Vertebrate Pests: Principles andStrategies (Braysher 1993), which is acompanion book which should be r eadtogether with these guidelines. Braysher(1993) explains why national guidelines formanaging pest animals wer e developed, thedevelopment process, and the principles onwhich pest management should be based.The need to focus on damage caused by thepest and not the pest itself is str essed.

As stated in Braysher (1993), a set ofguidelines for all vertebrate pests, takingaccount of the links between them and otheraspects of land management, would havebeen more desirable than the single speciesapproach adopted in the guidelines. Thiswould have been consistent with the holisticapproach to land management advocatedunder the Ecologically SustainableDevelopment strategy and Landcar e.Although this has not been practicable, allthe guidelines, including this one, considerinteractions between species and otheraspects of land management.

The guidelines are principally for state,territory and Commonwealth landmanagement agencies, so that they can mor eeffectively manage fox damage thr oughbetter coordination, planning andimplementation of r egional and localmanagement programs. The Commonwealthhas a major inter est in the management ofvertebrate pests, as a manager ofCommonwealth lands, thr ough suchinitiatives as the Vertebrate Pest Program, theNational Landcare Program and the NationalStrategy for the Conservation of Australia’sBiological Diversity. Achieving the strategic

approach to the management of foxes andother vertebrate pests involves establishingfour key components as shown in Figur e 1.Such an appr oach has been adopted fordeveloping these national guidelines.

Defining the problem

Historically, the fox was consider ed a pestbut not a significant pr edator of livestock inAustralia. Recent studies by Lugton (1993)have again focused on this aspect of foxdamage. However, the most importantchange has been the r ecognition that foxpredation of wildlife is a major pr ocessthreatening the survival of many nativeanimals. Chapters 1 and 2 outline the historyof the fox in Australia and trace the sour cesof wild populations. Fr om this historical base,what is known about fox biology is thenpresented.

Chapter 3 r eviews the evidenceconcerning the economic and envir onmentalimpact of foxes in Australia. These impactsare not well quantified, and further studiesare needed to addr ess these deficiencies.

Management plan

The primary aim of a land manager is tomeet the desir ed conservation and/orproduction outcomes for the land, usingpractical, cost-ef fective methods withoutdegrading the soil and other natural r esourceson which the long-ter m sustainability of theland depends. The envir onment in whichland managers, including far mers, operateis highly variable. A number of factorsinfluence the desir ed outcomes, such asfluctuating commodity prices, climaticvariability including dr ought, plant andanimal pests, grazing pr essure, quality ofstock and social factors such as the influenceof animal welfar e and conservationorganisations.

The objective of the national guidelinesis to encourage the adoption of ‘best practice’fox management as distinct fr om reactivemeasures by individuals and agencies. ‘Bestpractice’ is based on cooperative action andadoption of a whole pr operty planning


Defining Problem

(Section 8.3)

• who has the problem • real or perceived • define harmful • impact – economic – environmental • measure impact • mapping

Management Plan

(Section 8.4)

• objectives • management • options – local eradication – strategic management – crisis management – no management • performance • criteria • allocating • management • units • management • strategy

Implementation (Section 8.5)

• group action – ownership • whole farm/district • government role

Monitoring and Evaluation (Section 8.6)

• assess control • compare over time • techniques • evaluation of outcome

Strategic management of foxes at the national level

Figure 1: Strategic approach to managing fox damage.

approach to management, pr eferably linkedto a regional or total catchment plan.

The guidelines will have met their purposeif the strategic appr oach they advocate isaccepted and implemented by a significantnumber of agencies and individuals. Thisconstitutes the criterion of per formance.

Chapter 4 r eviews managementtechniques for rabies.

A national strategy for managing foxesincludes encouraging the gr oup approach.Community attitudes strongly influence themanagement of foxes, and these issues ar ediscussed in Chapter 5.

Chapter 6 reviews both past and curr entmanagement and Chapter 7 r eviewstechniques for measuring and contr olling foximpact and abundance. Various managementoptions are discussed in Chapter 8. Theyinclude local eradication; strategic

management (sustained, targeted or one-off);commercial harvesting and crisismanagement.

There are many ways of contr olling foxes,but the integration of several techniques ina planned way, taking into account overallland management, fox biology, and othervariables will improve their ef fectiveness. Theway in which to develop an integrated foxmanagement program is described in Chapter8. This chapter also r eviews the elements offox management strategies at local andregional levels, including r ecommendedmanagement techniques and strategies forfox control for hypothetical agricultural andconservation systems.

Implementation

At the national level, ‘best practice’ r equiresthat the various r oles and responsibilities of


governments, agencies, gr oups andindividuals are taken into account andintegrated. Chapter 9 r eviews these issues,and describes how these factors ar eintegrated into an overall managementstrategy.

Monitoring and evaluation

Monitoring is an essential part of foxmanagement. Operational monitoringmeasures the ef ficiency of the contr olstrategy, assessing the cost-ef fectiveness ofcontrol over time. Chapter 7 r eviewsmonitoring requirements.

Performance monitoring seeks to evaluatethe outcome of the management plan; thatis, whether the conservation or agriculturalproduction targets set initially ar e being met.This is r eviewed in Chapter 8.

Both forms of monitoring enable managersto decide whether the management strategyneeds to be modified.

Strategic management at the localand regional level

These guidelines set out best practice foxmanagement at the national level based oncurrent knowledge. They bring together thebest available infor mation on ef fective foxcontrol, as a basis for better managementof the damage due to this pest.

Vertebrate Pest Program

In the Envir onment Statement of December1992, the Commonwealth Gover nmentprovided increased resources to completepreparation of the guidelines for managingAustralia’s major vertebrate pest species andto establish key demonstration pr ojects tofacilitate adoption of best practice pestmanagement. Projects will draw on themanagement strategies outlined in therelevant guidelines for each species. Formost species, including foxes, i t isanticipated that ‘best practice’ will evolvebased on experience gained fr omundertaking strategic management. Using

the management system to r efine the pestmanagement strategy is called lear ning bydoing.

It is expected that community-basedgroups will become incr easingly involvedin the strategic management of vertebratepests. The guidelines ar e designed tofacilitate the ownership of the pest pr oblemby such local gr oups, and the managementstrategy which might be developed andimplemented based on them.

Note: All money values thr oughout theguidelines are in 1993-94 Australian dollars.

Throughout this document ‘fox’ r efers tothe European red fox ( Vulpes vulpes).


1. History

Summary

Evolutionary origins of the European redfox (Vulpes vulpes) are uncertain. As amember of the Canidae, it may have evolvedduring the Eocene (30–50 million yearsago), possibly in North America. The fox wasfirst introduced to Australia in the 1860sand 1870s for hunting with horses andhounds. It occurs naturally only in thenorther n hemisphere and is foundthroughout most of the Palaearctic region.In Australia and elsewhere it has been asuccessful coloniser. Within 30 years of itsinitial release in southern Victoria in 1871,the fox attained the status of a pest innorthern parts of the state. Colonisation wasprobably assisted by the spread of the rabbitin Australia at about the same time. By 1893the fox was reported in New South Wales;in 1901 in South Australia; in 1907 inQueensland; and in 1912 in WesternAustralia. By the early 1930s, foxes were tobe found in most habitats all over mainlandAustralia with the exception of the tropicalnorth. There are no foxes in Tasmania.

1.1 Europe and America

Fossil r ecords suggest that the familyCanidae, to which foxes belong, evolvedsome 30–50 million years ago in the Eocene,probably in North America. The Canidaemay come fr om two separate lines withfoxes and jackals descending fr omCynodictis, and dogs and wolves fr omAmphicyon (Lloyd 1980).

The evolution of the r ed fox as a distinctspecies is poorly documented. Bones of theanimal are rare in all deposits which pr edatethe Stone Age (Zeuner 1963). Thr ee speciesof fox, including the r ed fox, occur in thePleistocene (11 000 to 1 million years ago)fauna of Eur ope and, fr om the MiddlePleistocene, the r ed fox is known fr om theThames deposits of Grays and Ilford in Essex(Zeuner 1963). In later Pleistocene times thethree species (red, corsac and arctic fox)

persisted and probably coexisted in Eur ope.As the ice r eceded to the Ar ctic at the endof the last glaciations, the ar ctic foxwithdrew to higher latitudes and the corsacfox to the steppes of Russia, whilst the mor eadaptable red fox advanced widely (Lloyd1980).

The history of the r ed fox in NorthAmerica deserves comment. The native r edfox of North America ( V. fulva) isconsidered by Churcher (1959) to be thesame species as V. vulpes. If so, then theformer might be r egarded as a race orsubspecies of the latter . Certainly, Eur opeanred foxes wer e introduced into Marylandin the middle of the eighteenth century andlater to Long Island (Lloyd 1980). Ther e isevidence that the early distribution of thenative fox did not extend below 40 ° Nlatitude and that the intr oduced red fox mayhave colonised the mor e southern areas asthese were opened up by Eur opean settlers.The two subspecies may then have met andinterbred resulting in a lar ger overall rangefor the species (Lloyd 1980).

1.2 Australia

Although newspapers r eported the intr o-duction of foxes as early as 1855, it is likelythat the first successful r eleases took placein southern Victoria in 1871 (Rolls 1969). Oneof these took place near Geelong in V ictoria,where rabbits had been r eleased a few yearsearlier. This may be one of the few exampleswhere a predator and its natural pr ey wereintroduced at about the same time. T wo foxcubs were shipped from England to Adelaidein 1869, but their subsequent fate isunknown. Nonetheless, foxes wer eapparently common in the Coor ong regionof South Australia by 1888. By 1893 the shir esof Euroa, Benalla and Shepparton (all inVictoria) had a bounty scheme on fox heads,indicating that the new arrivals quicklyattained the status of pests. New South W alesquickly followed suit with the declarationof foxes as noxious animals at Ar midale, andwithin a few years they wer e reported to bein southern Queensland.

Bureau of Resource Sciences 11

1

Foxes were first r eported to be in WesternAustralia, west of Eucla, in 1911–12 and 160kilometres west of the South Australianborder in 1915 (Long 1988). Their spr eadin the west was rapid, and some evidencesuggests that they colonised the last of theforested areas of the lower south-west ofWestern Australia at the same time as therabbit. Colonisation by foxes pr obablycontinued well into the 1950s, since Long(1988) records first sightings in the EastKimberley in 1968 and at Fitzr oy Crossingin 1958.

Thus the fox’s pr esent distribution, whichcovers all of mainland Australia except the

tropical north (Figur e 2), was achieved in100 years. However , the limits ar e not fixed.It is likely that the norther nmost limit offoxes alters with seasonal conditions,expanding and contracting in r esponse toa run of good seasons or a run of dr oughtyears. Similarly, Lloyd (1980) has indicatedthat in parts of Gr eat Britain, the distributionand density of foxes seems to have waxedand waned considerably over the pastcentury.

‘Foxes occur throughoutAustralia except for the

tropical north, Tasmania andsome smaller islands.’


Figure 2: Spread of the r ed fox in Australia (after Jar man 1986).

0 200 400 600 km

Frontier of spread

Victoria

Tasmania

New South Wales

QueenslandSouth Australia

Northern Territory

Western Australia

Tropic of Capricorn

1929

1920

1920

1930

1930

1931

1916

1916

1915

1910

1901

1901

1900

18801865

18931890

1870

190719001911–12

1925

1925

1932–34

1932

19341950–52

19321930–35

1920

Data from early bounty schemes inAustralia suggest that the fox spr ead mostrapidly across the inland saltbush andMallee country, and mor e slowly in theforested ranges near the coast (Jar man1986). However, in Western Australia, theearly spread seems to have been along thesouthern coastline with a succession ofsightings from Eucla in 1912 to Geraldtonin 1925 (Long 1988) (Figur e 2).

‘The rapid spread of foxes inAustralia was assisted by

deliberate human introductionsto new areas.’

If it is assumed that all Australian foxesoriginated from the early intr oductions toVictoria, then data fr om early sightingselsewhere on the continent suggest annualdispersal distances of up to 160 kilometr esper year. This is unlikely, for althoughdispersal movements of this magnitude havebeen recorded, they ar e the exception ratherthan the rule. Recent data on cub dispersalin Victoria (Coman et al. 1991) indicates an


1S

calp

num

bers

('0

00)

0

10

20

30

40

50

60

70

1949 1952 1955 1958

Year

1961 1964 1967 1970

Figure 3: Interrelationship between fox and rabbit populations as demonstrated by decr eased numberof fox scalps r eturned for bounty payment in V ictoria following the widespr ead outbreak ofmyxomatosis in 1951 (after Redhead et al. 1991).

annual dispersal distance of 11 kilometr eswith exceptional movements up to 30kilometres, although this was based on asmall sample size. While foxes dispersinginto an ar ea previously devoid of foxes mayhave dispersed mor e rapidly than mor erecent studies indicate, it is concluded thatthe early and rapid movement of foxes inAustralia was assisted by deliberate humanspread of the animal.

‘In Australia the spread andestablishment of foxes was

closely linked to the spread ofrabbits.’

The early history of fox intr oductions toTasmania is poorly documented thoughseveral introductions have been r ecorded(Lever 1985; Statham and Mooney 1991).Fortunately, none were successful.

The early spr ead and establishment offox populations was closely linked to thespread of rabbits. Australian studies on foxfood habits (Section 2.2.7) highlight the


Foxes Rabbits

Figure 4: Relative distribution of foxes and rabbits in Australia (after V ertebrate Biocontr olCentre 1992).

importance of rabbit in their diet, and thedata on early spr ead of foxes suggest thatthey spread more rapidly wher e rabbitswere present. Long (1988) noted that inWestern Australia, the fox appear ed tofollow approximately the same invasionpath as the rabbit, although several yearslater.

The interrelationship between foxes andrabbits is dramatically illustrated in Figur e3.In Victoria, a statewide bounty scheme for

fox scalps began in 1949. Numbers r eturnedfor payment quickly r ose to a high level butthen fell dramatically in 1952–53 whenwidespread myxomatosis outbreaks reducedthe rabbit population to a very low level.Significantly though, scalp numbers r oseagain within a few years, possibly indicatingthe ability of foxes to switch to alter nativefood sources. Figure 4 shows the high degr eeof overlap between the distribution of rabbitsand foxes.

2. Distribution andbiology

Summary

The red fox is widely distributed throughoutthe southern half of mainland Australiaand can survive in habitats ranging fromarid through to alpine as well as urban.The only limitations on distribution appearto be the presence of dingoes, at least insome areas, and the tropical climate ofnorthern Australia. In non-urban areas itappears to be most abundant in fragmentedhabitats typically found in agriculturallandscapes. These offer a wide variety ofcover, natural food and den sites. Densityestimates in Australia, although few, rangefrom 0.2 adults per square kilometre incoastal forest up to 12 adults per squarekilometre in urban populations.

Females reproduce only once a year.Gestation lasts 51–53 days with most cubsborn during August and September. Meanlitter size is four up to a maximum of aboutten. Both sexes become sexually maturefrom ten months of age. Although socialgroups of one male and several vixens doexist, most foxes are thought to have onlyone mate. Males may also leave their normalterritory temporarily in search of othermating opportunities.

Overseas the disease most commonlyassociated with foxes is rabies, which is onlyendemic in Europe and North America.Many other infectious diseases occur infoxes, although little is known of theirincidence in Australia, or their impact onpopulation regulation. These includemange, canine distemper, parvovirus,toxoplasmosis, canine hepatitis, tularaemia,leptospirosis, staphylococcal infections andencephalitis. Like most carnivores that feedon a wide range of prey, foxes also carry avariety of endoparasites. The incidence ofhelminth parasites, in foxes in particular,has been intensively surveyed in south-eastern Australia because of their potentialtransmission to domestic animals. Otherthan the dingo, the fox has few natural

predators, although cubs can be taken bybirds of prey and dogs. Population turnoverappears to be rapid, but its causes, partic-ularly in Australia, are poorly understood.Mortality of foxes is thought to be duemainly to the impact of drought on theirprey, principally rabbits, and that causedby humans. Mange and distemper may alsobe significant contributors.

Fox groups generally have well-definedhome ranges with spatially stable borders.The size of a home range depends on theproductivity of the environment, but variesfrom 1600 hectares in Canadian tundra to30 hectares in urban areas. Foxes aremostly active from dusk to dawn and rarelytravel more than ten kilometres per daywithin the home range. Dispersal iscommon, particularly in sub-adult males.It commences in late summer and continuesthrough to the onset of breeding in winter.Exceptional dispersal distances of over 300kilometres have been recorded with averagesof between 2–40 kilometres.

Although predominantly carnivorous,the fox is an opportunistic predator andscavenger with no specialised food require-ments. Diet studies conducted in Australiashow sheep taken as carrion, rabbits andhouse mice to be the most common fooditems.

2.1 Distribution andabundance

2.1.1 Worldwide distribution offoxes

‘Foxes are now found inseveral Australian cities.’

The r ed fox is the most common andwidespread member of its genus, whichincludes 11 other species worldwide(Clutton-Brock et al. 1976). It occursnaturally in the norther n hemisphere only,where it is distributed thr oughout most ofthe Palaearctic region (Lloyd 1980). Pr esent-day distribution of the r ed fox is pr esentedin Figure 5.


2

The success of the r ed fox in nearly allenvironments is attributable to a highlyadaptable and unspecialised lifestyle withno specific habitat r equirements (Corbet andHarris 1991). Historical evidence suggeststhat the red fox has expanded its naturalrange over the last 200 years (Lloyd 1980;Voigt 1987) possibly in part due todiminished competition with lar ger canidssuch as the wolf ( Canis lupus). Since themid-1940s, urban foxes have becomecommon in British cities (Harris and Rayner1986) and recently have occupied a numberof Australian cities such as Adelaide,Brisbane, Canberra, Melbourne, Perth andSydney (C. Marks, D NRE, Victoria, pers.comm. 1994).

2.1.2 Australian distribution

The red fox is found thr oughout the southernhalf of Australia with the exception ofTasmania and Kangaroo Island (Jarman 1986,Wilson et al. 1992). It occurs fr om the aridcentre to the alps and is also found in urbanAustralia. In central Australia, its distributionis similar to that of the rabbit, but appearsto be limited in some ar eas of easter n and

western Australia by the pr esence of highdensities of dingoes. Sharp boundaries indensity along parts of the New South W alesborder are probably due to the dingo fenceand the displacement of foxes by dingoes.However, in areas of South Australia adjacentto the New South W ales border, foxes appearto be pr esent even where there are highdensities of dingoes. Her e, dingoes pr obablyinfluence fox density rather than distribution.Only isolated pockets occur in the far north,such as the Kimberley r egion of WesternAustralia (King and Smith 1985) and theVictoria River District and Barkly T ablelandsof the Norther n Territory (Wilson et al. 1992).Foxes appear to have r eached the northernlimit of their range as r ecently as the last 30years (Jarman 1986). The norther n limit offox distribution in Australia may r eflectclimatic preference. The red fox does notoccur in the humid tr opical regions of NorthAmerica and Asia although other Vulpesspecies do (Wilson et al. 1992).

2.1.3 Density estimates

The nocturnal and elusive natur e of the r edfox makes population density estimates


Figure 5: Present-day world distribution of the r ed fox (after Jar man 1986).

difficult to determine and often inaccurate.This is further complicated by the cyclicalchanges in fox densities associated with preyabundance. Their occurrence in such a widevariety of habitats also makes it difficult toapply a common census technique, makingcomparisons between different populationsat best, tenuous. Details of populationestimation techniques are presented inChapter 7.

Estimates of fox densities vary from ashigh as 15 adults per square kilometre inurban areas of Britain (Harris and Rayner1986; Harris and Smith 1987) to as low as0.1 adults per square kilometre in tundraand boreal forest (Voigt 1987). Like all otherspecies, population density depends verymuch on the productivity of theenvironment.

In Australia, fox density is perceived tobe highest inside the dingo fence in semi-arid New South Wales where there is anabundance of rabbits and carrion, andlowest along the more heavily timberedcoast and ranges (Wilson et al. 1992). Thefew density estimates which are availableinvolve only a limited number of relativelysmall study sites. These are presented inTable 1. In conflict with the Wilson et al.observation, these figures suggest that higher

densities are more common in the temperategrazing country of south-eastern Australia.

2.1.4 Habitat preferences

The worldwide distribution of the red fox,ranging from tundra to the desert as wellas urban areas, suggests that it can survivein most environments. How an animal usesthe specific habitats within the confines ofits environment (specified by a territory orhome range) is determined by acombination of factors including the distri-bution of food and water, shelter frompredation and climate, breeding sites andthe paths which link the various habitatpatches. Identification of habitat require-ments and how they are used are importantin the design of effective strategies formanaging fox damage.

‘Worldwide fox distributionranges from tundra to desert.

Red foxes are not found intropical climates.’

Habitat use by urban foxes has beenstudied in a number of British cities (Harris1977; Macdonald and Newdick 1982; Kolb1985; Harris and Rayner 1986). The mostimportant urban habitat requirementappears to be that of cover (Harris 1977).


2

StudyStudyStudyStudyStudy HabitatHabitatHabitatHabitatHabitat LocationLocationLocationLocationLocation Fox densityFox densityFox densityFox densityFox density

Coman et al. 1991 Temperate grazing Central Victoria 3.9

Thompson and Fleming 1994 Temperate grazing Northern Tablelands, NSW 4.6–7.2

Newsome and Catling 1992 Dry sclerophyl forest South Coast, NSW 0.2

Newsome and Catling 1992 Semi-arid grazing Western NSW 2.0

Marlow 1992 Arid grazing Western NSW 0.9

T. Bubela (Sydney University, Sub-alpine South-east NSW 1.8

pers. comm. 1994)

D. Algar (CALM, WA) and Semi-arid grazing South-west 0.6–0.9

P. Thomson (APB, WA) – pers. Western Australia

comm. 1993

C. Marks (DNRE, Vic., pers. Urban Melbourne 0–12

comm. 1994)

Table 1: Density estimates (foxes per square kilometre) of Australian fox populations.

Exposed habitats such as fr ont gardens,parkland and playing fields ar e avoided,with undisturbed habitats such as backgardens, rough ground and cemeteriespreferred. There appears to be a temporalpattern, with foxes avoiding habitats at timeswhen human activity is high. Roads ar e usedfor travel between habitat patches. Thissituation may change towards the suburbanfringes or in urban ar eas interspersed withlarge tracts of r ough ground or open space(Macdonald and Newdick 1982; Rosatte etal. 1991).

‘Foxes are often abundant inagricultural areas as they

offer a wide range of cover,food and den sites.’

These studies have been made easier inthe urban ar eas because of the even andclearly defined distribution of habitats andthe limited areas for travel. However , it ismore difficult to make clear interpr etationsof habitat preferences in rural or wilder nessareas. The fox is pr obably most abundantin fragmented environments typically foundin agricultural landscapes because theseoffer a wide variety of cover , food and densites. More uniform, open environments areless favoured as are heavily for ested ormountainous areas. Foxes do not liveentirely within closed canopy for ests but

can penetrate some distance into them insearch of food (Jar man 1986). The r ed foxappears to be absent fr om areas withtropical climates, such as Asia, although thereasons for this ar e unclear. The fox’s habitatpreference within specific envir onments hasnot been studied in Australia.

2.2 Biology

The life history of the r ed fox has beenextensively studied in the norther nhemisphere (reviewed by Burrows 1968;Storm et al. 1976; Pils and Martin 1978; Lloyd1980; Zimen 1980; Harris 1986; Henry 1986;Macdonald 1987; Voigt 1987). However,there have been few biological studies offoxes in Australia (Ryan 1976a; Coman 1988;Coman et al. 1991; Phillips and Catling 1991;Marlow 1992). Most of these studies haveconcentrated on the pr edatory relationshipbetween foxes and the sheep industry, foxdiet or fox endoparasites. The biologicalinformation presented here is ther eforebased mainly on observations fr om thenorthern hemisphere. The extent to whichthis information applies to foxes in Australiais unclear, emphasising the need to betterunderstand the biology of the fox inAustralia, especially those aspects essentialfor developing contr ol strategies.


The European red fox adapted well to Australian habitats.Source: CSIRO

2.2.1 General description andclassification

The red fox is a member of the familyCanidae which includes wolves, jackals andcoyotes. Males ar e slightly lar ger thanfemales. Both males and females, but par -ticularly females, have seasonal variationsin body weight. Adults have a head andbody length of 570–740 mm, a tail length of360–450 mm and weigh between 4.5–8.3kilograms (Coman 1983).

Behavioural traits, which ar e common tomany other canids, include the use of dens(commonly enlarged rabbit burrows) for thebirth and early caring of cubs; surplus killingof prey and caching of food for laterconsumption; predominantly nocturnal andcrepuscular activity; and territorial familygroups with juvenile dispersal common.Numerous scent glands, particularly analsacs, are used to mark territories. They havea wide range of vocalisations, mostcommonly heard during the mating season.

2.2.2 Reproduction

The red fox is monoestrus, vixens comingon heat only once during the br eedingseason and then for only two to thr ee days.Females are reproductively active fr om July

to October with a peak during August insouth-eastern Australia (McIntosh 1963a;Ryan 1976a), although ther e may belatitudinal variations as found in the norther nhemisphere (Lloyd and Englund 1973; Stor met al. 1976). R yan (1976a) found sper m orspermatids present in males in every monthexcept January, with peak pr oductionoccurring from June to August. Gestationlasts 51–53 days with most cubs bor n duringAugust and September.

‘Vixens come on heat once ayear. Cubs are mostly born in

August and September.’

Mean litter size is four up to a maximumof around ten. Cubs ar e suckled until fourweeks, then pr ogressively weaned ontosolids. Both sexes become sexually matur efrom ten months of age. The number of non-breeding vixens in any population is highlyvariable, being most common wher epopulations are subject to low levels ofcontrol and least common wher e mortalityrates are high (Corbet and Harris 1991). Thismay be due to the social suppr ession ofreproduction in large groups. In these casessome non-breeding females may act as‘helpers’, which are so defined because oftheir supportive r ole in raising cubs(Macdonald 1979). The mechanisms for thisbehaviour remain unclear. Foxes are thought


2

Foxes use dens for the birth and early caring of cubs.Source: CSIRO

to be largely monogamous. However ,polygamous social groups of one male andseveral vixens do exist, the vixens invariablybeing closely related (Macdonald and Bacon1982). Males are also known to leave theirterritory in search of other mating oppor -tunities, but this occurs during the br eedingseason and has minimal management impli -cations.

‘The average litter is four cubs;maximum litter is about ten

cubs.’

2.2.3 Diseases and parasites

The disease most commonly associated withthe fox, and one to which the species isparticularly susceptible, is rabies (W andeleret al. 1974; Macdonald 1980). It is a majorpublic health concer n throughout Europeand North America wher e the disease is

endemic, and also in Australia wher e everyeffort is taken to pr event its introduction(Chapter 4). Many other infectious diseasesoccur in foxes, although little is known oftheir incidence in Australia or impact onpopulation r egulation. These includemange, canine distemper , parvovirus,toxoplasmosis, canine hepatitis, tularaemia,leptospirosis, staphylococcal infections andencephalitis viruses (Voigt 1987).

Foxes carry a variety of endoparasites(Lloyd 1980). The incidence of helminthparasites in foxes in particular has beenintensively surveyed in south-easter nAustralia because of their potentialtransmission to domestic animals (Pullar1946; Coman 1973a; Ryan 1976b). Mostprevalent are Taenia pisiformis, T. serialis,Spirometra erinacei, Dipylidium caninum,Toxocara canis, Uncinaria stenocephalaand Ancylostoma caninum.


Figure 6: Variations with time of rabbit and pr edator (cat and fox) numbers at Y athong NatureReserve in central-wester n New South Wales (after Newsome et al. 1989)

Predators

J JJ DJ JJ DJ J1979 1980 1981

0

2000

4000

6000

0

50

Rabbits

Drought

Sp

otl

igh

t co

un

ts in

18

km

‘Foxes can carry rabies andother diseases, although fox

rabies has so far been kept outof Australia.’

In some parts of the world foxes ar e animportant end host for the hydatidtapeworm (Echinococcus granulosus).Although thousands of foxes have beenexamined for signs of this parasite inAustralia, it has only been found ina fewanimals, and then at low levels.Consequently, it is assumed that foxes donot play an important r ole in the life cycleof Echinococcus in rural Australia despitetheir susceptibility to this parasite. Thesituation is less clear in urban ar eas whereit appears that even a few infected foxes ar ea risk to human health (Jenkins and Craig1992).

Ectoparasites known to occur in Australia,and which are found on foxes in the norther nhemisphere (Corbet and Harris 1991),include fleas ( Spilopsyllus cuniculi, Pulexirritans, Ctenocephalides canis), ticks ( Ixodesricinus) and mites ( Sarcoptes scabiei,Demodex folliculorum, Notoedres spp.,Otodectes cyanotis and Linguatula serrata).Ringworm (Microsporum) is also r ecordedoccasionally. In a r ecent study, Phillips andCatling (1991) suggested that the observedlow fox density in rainfor ests of souther ncoastal New South Wales may be due tomortality resulting from the high incidence

of dog ticks ( Ioxodes holocyclus). Thissuggestion warrants further study.

2.2.4 Mortality factors

The red fox has few natural pr edators,although cubs can be taken by bir ds of preyand dogs (Corbet and Harris 1991) and ther eis circumstantial evidence that dingoes mayinfluence the distribution of foxes (Section2.1.2). In Australia, dingoes ar e known tokill and eat adult foxes (P . Bird, APCC, SApers. comm. 1993). Population tur noverappears to be rapid, but causes, particularlyin Australia, ar e poorly understood (Coman1983). In a sample of 317 foxes killed byhunters in south-easter n Australia, it wasfound that 54% of animals wer e less thanone year old and 71% less than two yearsold with few (4%) animals surviving beyondfour years (Coman 1988).

‘Most foxes are killed by peopleor the effects of drought.’

Most deaths are believed to be due tohuman intervention and the impact ofdrought on their main pr ey, rabbits. Stormet al. (1976), in a North American study,reported that more than 80% of tagged foxesdied as a r esult of shooting, trapping or r oadkills. Harris (1978), in a survey of Britishurban fox mortality found that 61% of adultsdied from road accidents, 18% wer e delib-


2

Cats

01972 1973 1974 1975 1976 1977 1978 1979 1980 1981 19821971

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bits

per

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5

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25

Flea introduced

FoxesRabbits

Cat

s/fo

xes

per

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km

Figure 7: Variation in fox and feral cat numbers in r elation to changes in rabbit numbers in south-western Western Australia (after King and Wheeler 1985). Ther e was an incr eased incidence ofmyxomatosis following the intr oduction of the Eur opean rabbit flea.

erately killed by man, 10% died from disease,3% from fights, less than 1% from parturitiondeaths and the remainder (7%) frommisadventure or unknown causes. Sarcopticmange is a significant mortality factor(Trainer and Hale 1969; Pils and Martin1978; Tullar and Berchielli 1982), as ofcourse is rabies where it is endemic(Macdonald 1980). Secondary poisoning asa result of pest control programs, principally1080 control of rabbits, is not uncommon(McIlroy 1981) as is primary poisoning frombaits intended for larger carnivores such asdingoes (McIlroy 1986). The number of baitsdistributed intentionally for fox control inAustralia has risen dramatically in recentyears. This is possibly due to decreasedhunting pressure as a result of the collapsein the fur trade and increasing concern forthe damage they cause to native wildlifepopulations and agricultural production(Chapter 3).

‘Rabbits are the main prey offoxes in the southern pastoral

areas of Australia.’

In the southern pastoral zones ofAustralia, rabbits are the principal prey offoxes and feral cats. When rabbitpopulations crash, either due to drought(Figure 6) or outbreaks of myxomatosis(Figure 7), fox and feral cat populations alsocollapse after a lag period (Brooker 1977;

Myers and Parker 1975a, b; Newsome et al.1989; King and Wheeler 1985; Redhead etal. 1991). During the lag time, foxes arebelieved to prey heavily on the remainingrabbits and on native fauna. The role foxesplay in regulating rabbit density, and theimplications of managing or not managingfoxes for native wildlife during rabbitmanagement programs, is unclear and needsfurther investigation.

‘We need to know more abouthow foxes affect rabbit and

wildlife populations.’

2.2.5 Movements and home range

Red fox family groups generally occupy well-defined home ranges with non-overlapping,adjoining and stable borders (Storm 1965;Ables 1969; Sargeant 1972; Pils and Martin1978; Voigt and Macdonald 1984).Overlapping home ranges reported in somestudies are thought to be due to inadequatedata collection and analysis or to the studyanimals being closely related (Voigt 1987).However, Doncaster and Macdonald (1991)observed continually drifting territories in anurban fox population. The combinedevidence from studies of scent marking,social encounters and movement patternssuggests that home ranges are the same asterritories (Henry 1979; Macdonald 1979).


HabitatHabitatHabitatHabitatHabitat Home range (ha)Home range (ha)Home range (ha)Home range (ha)Home range (ha) ReferenceReferenceReferenceReferenceReference

Tundra (British Columbia) 1611 Jones and Theberge 1982

Farmland (Ontario) 900 Voigt and Tinline 1980

Farmland (Victoria) 610 Coman et al. 1991

Alpine (New South Wales) 550 Bubela 1993

Forest (New South Wales) 416 Phillips and Catling 1991

Farmland/woodland (Western Australia) 340 D. Algar (CALM, WA) andP. Thomson (APB, WA) – pers.comm. 1993

Forest/urban (West Germany) 133 Zimen 1984

Urban (England) 30 Saunders et al. 1993

Table 2: Comparison of mean home range estimates (minimum convex polygons) for foxes indifferent habitats.

‘Fox family groups usuallyoccupy well-defined home

ranges.’

A home range is generally proportionalin area to the amount of resources itcontains. Foxes in habitats with abundantfood sources have smaller home ranges(Harestad and Bunnell 1979; Lindstedt et al.1986). The variation in fox home range sizeas implied by resource productivity indifferent environments is shown in Table 2.Voigt and Macdonald (1984) proposed thatthe pattern of mortality and the extent ofseasonal climatic variation also contributedto home range size, and concluded that redfoxes are so variable in their behaviour thatany extrapolations to an area based onstudies from another should be viewed withcaution. This means that fox management,especially in terms of baiting intensity andthe size of fox-controlled buffer zonesneeded for the protection of a specific area,needs careful consideration (Section 7.5).

The extent to which foxes can patrol andhence maintain a territory is influenced by

the size of the territory. An urban fox witha home range of 30 hectares is able to visitall boundaries two to three times in a night(Saunders et al. 1993). In contrast, Sargeant(1972) found that rural foxes with homeranges of 250–750 hectares required twoweeks to cover the entire territory. Thesedifferences may result in varying levels ofencroachment between neighbours as wellas the extent of social contacts. Apart fromthis, the most common incidences of foxesdisregarding territorial boundaries occur asa result of dispersal behaviour or adult malessearching for mating opportunities. Dailytravelling distances by resident adults withintheir territories rarely exceed ten kilometres,with most activity between dusk and dawn(Voigt 1987; Saunders et al. 1993).

‘Adult foxes rarely travel morethan ten kilometres per day.’

2.2.6 Dispersal

Dispersal by the red fox has been studiedextensively in Europe and North America


2

Food itemFood itemFood itemFood itemFood item % Occurrence% Occurrence% Occurrence% Occurrence% Occurrence % Volume% Volume% Volume% Volume% Volume

Sheep 31, 29 20, 19

Rabbit 39, 25 35, 20

House mouse 26, 15 14, 10

Macropod species 3, 1 2, 1

Possum species 7, 1 5, 1

Pig 1, 5 1, 5

Fox 3, 1 1, 1

Cattle 1, 2 1, 1

Domestic poultry 1, 4 1, 3

Bird species 19, 9 5, 5

Insects 36, 37 8, 12

Other invertebrates 7, 11 1, 4

Cold-blooded vertebrates 3, 5 1, 2

Plant material 57, 38 3, 12

Table 3: Percentage occurrence and percentage volume of major food items identified in the stomachsof foxes by Coman (1973b) (first figure) and Croft and Hone (1978) (second figure).

because of the importance of this behaviourto the spread of rabies (Phillips et al. 1972;Steck and Wandeler 1980). The majority ofdispersal occurs in sub-adult foxes, partic -ularly males, commencing in late summerand continuing through to the onset ofbreeding in winter.

‘The greatest movement offoxes occurs when young

males disperse.’

A variety of dispersal patter ns have beenrevealed in radio-tracking studies. Thesesuggest two distinct phases: sudden, quickand mainly straight line travel followed byslower, less dir ected movements that persistuntil the animal establishes the boundariesof its new territory (Zimen 1984). A seriesof exploratory trips prior to the maindispersal event ar e also common. All ofthese phases occur over a r elatively shortperiod. Longer dispersal distances ar eassociated with less pr oductive environ-ments. Exceptional movements of over 300kilometres have been r ecorded in NorthAmerica and 100 kilometr es in Eur ope(Corbet and Harris 1991). Mean dispersaldistances are much smaller than this, rangingfrom 2.8–43.5 kilometr es for males and1.8–38.6 kilometres for females (T rewhellaet al. 1988). In Australia, Coman et al. (1991)in central V ictoria, observed a meandispersal distance of 11 kilometr es basedon a study of 13 dispersing animals. Marlow(1992) monitored the dispersal of five femalefoxes which dispersed a mean distance of3.5 kilometres. In a r ecent study in southwestern Australia, Marlow and Thomson(WA CALM and APB, pers. comm. 1995)observed mean juvenile dispersal in malesof 43 km (n=7, range 9–170 km) and femalesof 15 km (n=6, range 6–22 km).

2.2.7 Diet

Although predominantly carnivorous, thered fox is an opportunistic pr edator andscavenger with no specialised food r equire-ments. There have been several studies onthe diet of the fox in Australia mainlybecause of concer n about its r ole as a

predator of sheep and native fauna(McIntosh 1963b; Martensz 1971; Ryan andCroft 1974; Brunner et al. 1975; Seebeck1978; Bayly 1978; Gr een and Osborne 1981;Triggs et al. 1984; Brunner and W allis 1986;Baker and Degabriele 1987; W allis andBrunner 1987; Catling 1988; Br own andTriggs 1990; Lunney et al. 1990; McKay1994). Two of the most compr ehensive interms of areas covered were those of Coman(1973b); and Cr oft and Hone (1978). Theseinvolved the examination of over 2000 foxstomachs from throughout Victoria and NewSouth Wales. The most common items ar epresented in Table 3, although ther e werenumerous regional and seasonal variationswithin and between studies. Assumingenergy intake is best r eflected by percentagevolume, sheep (believed to be mostly takenas carrion), rabbit and the house mouse ar ethe most important food items to the fox ona statewide scale. Similar observations havebeen reported from fox populations in thenorthern hemisphere (Sequeira 1980). Foxesalso have some distaste for food items suchas insectivore and car nivore meat, althoughcannibalism of litter mates or pr edation byvixens on other litters is not uncommon(Macdonald 1977).

‘’Foxes are opportunisticpredators and scavengers with

no specialised foodrequirements.’

Sargeant (1978) quantified the pr eydemands of captive foxes. Cubs began toeat prey four weeks after birth. Ther eafter,prey consumption averaged 197 and271grams per cub per day for weeks 5–8and 9–12 r espectively, and 363 grams percub per day for the post-denning period.Feeding by adults averaged 321 grams peradult per day. Fr ee water was not neededby either cubs or adults. Saunders et al.(1993) constructed a generalised model toestimate the daily ener gy expenditure,excluding direct costs of r eproduction, forurban foxes. Based on yearly averages forthis study, an adult male r equired 2001kilojoules per day which was the equivalentof 372 grams of wild mammal or 524 grams


of scavenged meat. The implications ofthese food r equirements, particularly duringthe post-denning period, to pr ey biomasswithin the family gr oup territory ar esubstantial. Sargeant (1978) estimated thisto be equivalent to 18.5 kilograms per squar ekilometre (two adults and five cubs).

‘Sheep taken as carrion,rabbits and house mice are the

main food of foxes.’

While diet studies indicate the range ofprey consumed by foxes, diet studies aloneare not a r eliable indication of the extent ofdamage caused by foxes. Some endanger ednative species may occur only rar ely in thediet, but foxes may be having a significantimpact on their populations. Conversely,other species that occur consistently in thefox diet may be in suf ficient numbers thatthey can tolerate long-ter m fox pr edationwithout any r esulting decline in populationdensities. The damage that fox pr edationcauses to native fauna can only bequantified by scientifically designed andreplicated studies where fox predation isreduced and the r esponse of the pr ey ismonitored. The r esults of such studies ar eoutlined in Section 3.1.

‘Fox predation does notnecessarily have a significanteffect on the populations of

prey species.’

2.2.8 Social organisation

A combination of aggr essive and non-aggressive encounters, scent marking andvocalisations ar e used to maintain foxterritories (Sargeant 1972; Niewold 1980;Voigt and Macdonald 1984). Mostencounters are due to dispersal or adultmales trespassing on neighbouring territoriesin search of receptive females. To a lesserextent, females can r eturn to their territoryof birth and some foxes will explor e neigh-bouring territories per haps in search of food(Niewold 1980; Voigt and Macdonald 1984;Mulder 1985).

The composition of family gr oups varieswith habitat. Large territories in the American

Midwest (Sargeant 1972; Storm et al. 1976)and Ontario, Canada (Voigt and Macdonald1984) were found to be typically occupiedby only one adult pair of foxes along withtheir litter of cubs which eventuallydispersed. Although not well documented,most observations suggest that this is alsothe predominant family group compositionthroughout Australia. Macdonald (1979,1981), von Schantz (1981) and Mulder (1985)found that in ar eas with more food and otherresources, family groups tended to be lar ger,consisting of one adult male and up toseveral vixens. Within these groups, vixenswere usually related and only the dominantfemale produced a litter . Subordinatefemales are recognised as ‘helpers’ whichmay feed, guard, groom and play with thecubs of the br eeding vixen (Macdonald1979). Where more than one vixen br eedswithin the one family gr oup, communaldenning and care of young may occur (T ullaret al. 1976). The pr esence of only a fewsolitary males in these mor e productive areassuggests higher male mortality (V oigt 1987).Von Schantz (1981) also concludes that it isin the best inter est of the dominant pair tofirst expel male of fspring as they have theleast to contribute to the raising ofsubsequent litters.

2.2.9 Conclusion

‘Relatively little is known aboutthe ecology of foxes in

Australia.’

Red foxes ar e highly adaptable and occupya wide range of habitats. Likewise, theyshow considerable variation in theirbehaviour, population density, r eproduc-tive potential and diet between thesehabitats. Macdonald (1981) ar gued that thesedifferences arose largely from the effects oftwo group variables: the patter n of resourceavailability, such as the abundance anddispersion of available food or the distrib-ution of cover or dens; and the intensity andpattern of mortality. Voigt (1987) suggestedthat the extent of seasonal climatic variationalso contributed to these variations. This is


2

particularly likely to be the case in Australiawhere the fox can be found fr om desert toalps (Figure 2). Because of these variations,accurate prediction of the behaviour of afox population, particularly without baselineinformation, is dif ficult if not impossible.Relatively little is known of fox ecology inAustralia. Studies are required, particularlyon population densities and movementacross dif ferent habitats, so that landmanagers can make soundly based decisionson appropriate management strategies.


3. Economic andenvironmentalimpacts

Summary

The fox has long been recognised as aserious threat to Australian native fauna,but until recently, this has been basedmainly on anecdotal and circumstantialevidence. For example, foxes have beenidentified as a factor limiting the success ofseven out of ten mainland reintroductionsof native fauna.

The best evidence of the primary role foxesplay in population regulation of some nativefauna comes from Western Australia. Foxcontrol resulted not only in substantialincreases in the populations of somemarsupials, but also in wider habitat use.However, for some native species, otherfactors beside predation may be operating.For example, it has been shown that factorswhich affect food for malleefowl chicks mayalso need to be addressed in addition topredation.

There is debate about the extent to whichfoxes are a useful biocontrol agent forrabbits, and whether there is a need tomanage foxes when rabbit populations are

reduced, in order to prevent increased foxpredation on native fauna. Foxesundoubtedly exert some control over rabbits,but not when conditions are favourable forgrowth of rabbit populations. In areas wherenative wildlife are at significant risk fromfox predation, fox management should beconsidered as part of rabbit control.

The economic impact of foxes inAustralia has been poorly studied but theprincipal losses almost certainly involvenewborn lambs. Earlier studies on thecauses of lamb loss generally dismisspredation as being insignificant on a stateor national level. More recent evidencesuggests that foxes may take from 10–30%of lambs in some areas.

Positive economic impacts of the foxrelate entirely to the value of fox pelts. Inthe recent past, high export prices for foxpelts provided significant income forAustralia, but the market fluctuates widelyand current pelt sales are low. The impactof commercial harvesting upon fox numbersand fox damage during the years of highpelt prices is unknown, but some anecdotalevidence suggests that numbers have risensince the high-level harvesting ceased.

One important social aspect of foxpredation in Australia is its potential impact


3

Phascogale species are believed to be at risk from fox predation.Source: Applied Biotechnologies


on ecotourism. Many of Australia’s wildlifespecies that are vulnerable to fox predationare unique and constitute an importanttourism asset.

3.1 Environmental impact

The fox has long been r ecognised as a seriousthreat to populations of native wildlife.Finlayson (1961) for example described how,over a 25 year period, r egions in centralAustralia were being stripped of its smallerwildlife species by incr easing populations offoxes. Similarly, the decline of species suchas the brush-tailed r ock-wallaby (Petrogalepenicillata) on mainland Australia isfrequently attributed to pr edation by foxes(Le Souef and Burr ell 1926; Wakefield 1954as cited in Short and Milkovits 1990). Suchobservations were, however, mostly based onanecdotal and circumstantial evidence. It wasnot until recent studies such as those ofKinnear et al. (1988) and Priddel (1989)quantified the extent of fox impact on wildlifethat land managers began to call for mor eeffective management of foxes.

‘Foxes can pose a seriousthreat to populations of native

animals.’

Because Australian native fauna did notco-evolve with the fox, susceptible pr eyspecies may have few strategies to avoidpredation by this animal. Further more, theimpact of the fox on wildlife has pr obablybeen exacerbated by habitat fragmentationand modification since Eur opean settlement(Mansergh and Marks 1993).

‘Because they did not co-evolvewith the fox, Australian native

animals may have fewstrategies to avoid fox

predation.’

Compared to other continents, thedamage to Australian wildlife since Eur opeansettlement has been catastr ophic and unpar-alleled other than for some island faunas. Atleast 20 species of Australian mammals havebecome extinct. This r epresents about one-half of the world’s mammal extinctions in the

last 200 years; a further 43 species ar e judgedto be either endanger ed or vulnerable(Commonwealth Endangered SpeciesAdvisory Committee (ESAC) Report 1992).

‘The impact of foxes on wildlifehas probably been exacerbated

by habitat modification andfragmentation.’

Undoubtedly the causes ar e complex.The ESAC (1992) r eport discusses a suiteof threatening processes including habitatloss; habitat change and degradation;impact of intr oduced animals and plants;disease; exploitation; and climatic change.A threatening process which has r ecentlycome to light is the impact of pr edation byfoxes on native marsupials and on themalleefowl (Leipoa ocellata). Except forsome detailed studies of fox pr edation ona limited range of W estern Australian nativemammals and some work by Priddel (1991)on malleefowl, ther e is little quantitativeinformation on the damage foxes cause tonative fauna (Pech et al. 1995). However ,there is a considerable number of anecdotaland observational r eports. Consequently,the examples in these guidelines ar e heavilybiased toward Western Australia althoughit is likely that the fox is having a similarimpact in other parts of Australia.

3.1.1 Fox removal studies inWestern Australia

In Western Australia, the impact of foxpredation on some marsupials has beenexamined in a series of pr edator removalexperiments (Kinnear et al. 1988 andunpublished works; Friend 1990; Morris1992). Such experiments have yieldedsubstantial and consistent populationincreases by a variety of marsupial species.The results suggest that not only has ther ebeen substantial population incr eases, butalso a wider use of the habitat when thepredation pressure is lowered. Some r esultsfrom these predator removal experimentsare described below.



3

Rock-wallabies (Petrogale lateralis)

Rock-wallabies wer e once commonthroughout south-west Western Australia. By1979 only six isolated colonies existed andthese were in decline (Kinnear et al. 1988).In a predator removal experiment, foxes wer econtrolled using 1080 baits in two colonies;

and three colonies served as experimentalcontrols (no fox contr ol). All populations wereperiodically assessed befor e and after foxcontrol.

After eight years, the populations subjectto fox control increased four to fivefold (Figure

Wal

laby

num

bers

8a Querekin Census No Fox Control

0

5

10

15

20

1978 1980 1983 1986Year

1988 1990

Wal

laby

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8b Tutakin Census No Fox Control

0

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1988 1990

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8c Sales Rock Census No Fox Control

0

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8e Nangeen Hill Census Fox Control from 1982

0

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1988 1990

Wal

laby

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8d Mount Caroline Census Fox Control from 1982

0

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1978 1980 1983 1986Year

1988 1990

Figure 8: Predator removal experiment conducted over eight years in W estern Australia for fivecolonies of r ock-wallabies (Petrogale lateralis). Three colonies received no tr eatment (Figure 8a,b,c),while foxes wer e controlled in two other colonies (Figur e 8 d,e) (after Kinnear et al. 1988). Note:Variable y-axis scales used for wallaby numbers at different sites.


8d,e). Those not subject to fox contr olremained the same, or fluctuated and thendeclined (Figure 8a,b,c). A thir d populationin an area having no fox contr ol was reducedto a single, barr en female. Rock-wallabieshave since been r eintroduced into one site(Querekin) in association with fox contr ol,and their numbers have incr eased.

Rothschild’s rock-wallabies (Petrogale

rothschildi)

Another fox r emoval experiment wasconducted to determine the impact of foxes

on Rothschild’s rock-wallabies in the DampierArchipelago (J. Kinnear, unpub.). This wallabyis endemic to W estern Australia and isrestricted to the Pilbara and Gascoyne r egions.Foxes have invaded Dolphin Island (whichcarries P. rothschildi) by crossing a narrowpassage that separates the island fr om themainland (the Burrup Peninsula). EnderbyIsland has rock-wallabies but is fox fr ee.

Abundance indices derived fr om standardspotlight traverses showed a markeddifference in r ock-wallaby abundancebetween Dolphin Island and fox-fr ee EnderbyIsland. For every thr ee hours of spotlighting

Dampier Archipelago

Western Australia

1979

Fox free

No fox control

After fox control

Dampier

Enderby Island

Karratha

Dolphin Island56

0 5 10

Scale

15 20 km

1

27

58

N

Perth

1990

Figure 9: The r elative abundance of Rothschild’s r ock-wallaby (Petrogale rothschildi), before andafter fox control in the Dampier Ar chipelago. Enderby Island is fox fr ee while foxes had invadedDolphin Island by cr ossing the narr ow passage that separates it fr om the mainland (J. Kinnear ,unpub.).


3

21.5

Means of sampled sites

1.8

11

0

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3

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1989

1984

55

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012

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Figure 10: Percentage capture rate of bettongs ( Bettongia penicillata) after five years of fox contr olin Tutanning Nature Reserve. Light gr een columns show the captur e rate prior to fox contr ol; darkgreen columns show the captur e rate following five years of fox contr ol in the r eserve (J. Kinnear ,unpub.).

Although foxes have been implicated in the demise of the malleefowl,other factors are thought to be involved including habitat modification.

Source: D. Priddel, NSW NPWS


Num

bat s

ight

ings

per

100

km

0

1979 81 82 83 84 85

Year

Part of Dryandra baited

Whole of Dryandra baited

87 88 89 90 91 92

2

4

6

8

10

12

Figure 11: Numbat (Myrmecobius fasciatus) sightings in Dryandra State For est between 1979 and1992. Fox contr ol program implemented in 1982 (J.A. Friend, CALM, W A, pers. comm. 1992).

on fox-free Enderby, approximately 60 rock-wallabies were sighted, while on DolphinIsland (with foxes) only one r ock-wallabywas sighted.

The spotlight traverses wer e repeated aftera period of fox contr ol using 1080 baiting onDolphin Island. Following fox contr ol on thisisland, the sightings incr eased by nearly thirty-fold (Figure 9). Thus, r emoval of foxes fr omDolphin Island resulted in a marked incr easeof rock-wallabies on the island.

Bettong (Bettongia penicillata)

Tutanning Nature Reserve (2200 hectar es) isa natural bush r emnant in the wheatbelt ofWestern Australia, about 150 kilometr es south-east of Perth. The r eserve lost three speciesof marsupials, a numbat, a possum and a

bandicoot, between 1971 and 1975. T ammars(Macropus eugenii), bettong and brushtailpossums (Trichosurus vulpecula) declinedto very low numbers. The bettong, which wasformerly abundant in the r egion, but thoughtto be extinct because none wer e reportedduring a ten-year period, was located butfound to be in very low numbers. In 1984,the reserve was trapped for bettongs andseven were captured and r eleased. Captureswere successful only at two sites characterisedby dense cover (Figur e 10).

‘Fox control resulted inincreased numbers and

distribution of bettongs in aWestern Australian reserve.’

A bait ing pr ogram for foxes wasimplemented and maintained for five years.

In 1989, the r eserve was trapped again and63 bettongs wer e caught for appr oximatelythe same trapping ef fort. Prior to fox contr olthere were no captures on some trap lines.After fox contr ol the capture rate of bettongsincreased and was as high as 55% of trapsset in some ar eas. To summarise, not onlydid fox contr ol r esult in a populationincrease, it also enabled the bettong tooccupy and r eproduce successfully in alarger proportion of the r eserve (Figure 10).Tammar wallaby and brushtail possumnumbers also incr eased.

Numbats (Mymecobius fasciatus)

Dryandra State Forest (more than 10 000hectares) is a pocket of r emnant bushlandin the wheatbelt near Narr ogin, about 175kilometres south-east of Perth. It is a highlysignificant conservation site because of thepersistence of the numbat within itsboundaries. During the 1970s, the numbatpopulation declined to a low level (Friend1990). Similarly, tammar wallabies, bettongand brushtail possum wer e also uncommon.During monthly trapping and spotlightsurveys over two years (1969–70) ther ewere few records of these species and thetrapping success was less than 2% (A.Burbidge, CALM, WA, pers. comm. 1992).Additional ef forts to trap bettongs in 1975were unsuccessful.

‘Numbats and other nativeanimals increased in Dryandra

State Forest after foxes werebaited.’

A fox removal program was implementedin 1982 in a selected portion of Dryandra StateForest. The 1080 baiting was undertakenmonthly, over five years. Numbats incr easedsignificantly within the baited ar ea, but notoutside the baited ar ea (Friend 1990). In 1989the whole of Dryandra was tr eated with 1080meat baits. Since then numbats have incr easedsubstantially (Figure 11).

Following fox control, bettongs appearedto increase in numbers within the baited ar ea,and after thr ee years of r egular 1080 baitingof the whole Dryandra State For est area,

numbats, bettongs and brushtail possumsappeared to have incr eased. Tammarwallabies, once thought to be extinct, ar e nowcommonly seen in some ar eas.

3.1.2 Evidence from south-eastAustralia

In New South Wales, fox r emoval has beenshown to incr ease malleefowl survival.Priddel (1991, page 3) states: ‘Populationsin New South Wales are in drastic declineand imminent danger of extinction ... Themost significant threat to the survival of themalleefowl in New South Wales is theintroduced fox (Priddel 1989)... the threatposed by the fox can be reduced by acampaign of intensive baiting’.

‘Fox removal has been shownto increase malleefowl survival

in New South Wales.’

In a further study and fr om earlier reports,Priddel and Wheeler (1990) concluded thatferal cats and foxes wer e a major factorinfluencing the survival of this species.However, it was shown that contr ol ofpredators alone was not suf ficient to ensuresurvival of malleefowl chicks (Priddel 1991).He states:‘Other factors are implicated in thedemise of malleefowl, namely stock, goats,rabbits and fire’.

Fire opens the canopy and incr eases thevulnerability of malleefowl to avian pr edators(Priddel and Wheeler 1990). Food is a limitingfactor (Priddel 1991) on Y athong NatureReserve, New South Wales. The study showedthat newly hatched chicks, which wer ereleased into mallee wher e foxes have beencontrolled, starved unless given supplemen-tary food.

Phillips and Catling (1991) studied thehome range and activities of foxes in awilderness area of coastal south-easter nAustralia. Small and medium-sized mammalswere abundant and comprised 52% of thediet of foxes. Such high pr ey densities ar e incontrast to the Western Australian situation,but fox densities (and pr esumably predationpressure) were judged to be low.


3

During studies of the distribution andabundance of fauna in two for ested regions,one in the north, and the other in the southof eastern New South Wales (P.C. Catling,in preparation), foxes wer e found to beabundant in all 13 study sites of the souther nregion. At the same time small wallabieswere not found, quolls wer e present in onlyone area, and bandicoots in six ar eas, bothat very low abundance. In contrast, of theten northern study sites, foxes wer e onlyfound in four, at approximately half theabundance found in the south. Smallwallabies and quolls wer e present in nineareas, bandicoots in seven ar eas, and allwere mostly at high abundance.

Norman (1970) studied fox pr edation inshort-tailed shearwater (Puffinus tenuirostris)colonies in Victoria. He found predation ratesto be generally low (less than 2%) but couldnot identify unconfirmed kills nor the extentto which viable individuals wer e beingremoved from the colony. Hor nsby (1981)observed one instance of fox pr edation on ajuvenile euro (Macropus robustus) as well asseveral attempted kills of yellow-footed r ock-wallabies in the Flinders Ranges of SouthAustralia.

Regular inspection of tortoise nesting sitesalong the Murray River in South Australiashowed that 93% of eggs wer e taken by foxes(Thompson 1983). It was also found in thisstudy that the age structur e of tortoise speciesin the Murray contained a dispr oportionatelylarge number of old individuals, which wasattributed to egg losses. As older individualsdie and with juvenile r ecruitment restrictedby fox predation, tortoise populations alongthe Murray will continue to decline.

A list of native species believed to be atrisk from fox predation is pr esented atAppendix A.

3.1.3 Impact of fox removal onother predators

In Western Australian, numbats haveincreased from low densities during foxbaiting programs (Section 3.1.1), and numbats

have been successfully r eintroduced intowheatbelt reserves in concert with 1080baiting programs. In another ar ea of WesternAustralia, subsequent r esearch (Friend 1990)recently identified a second limiting factorapart from fox predation. A numbat r eintro-duction experiment into a natur e reserve inWestern Australia had not been as successfulas previous wheatbelt introductions despitefox control. There is evidence that pr edationby feral cats became the limiting factor . It isnot known why cat pr edation is a significantmortality factor in this semi-desert setting.Feral cats in this ar ea seem less inclined thanfoxes to take baits. It is subjective observationwhich also suggests that cats may incr ease indensity following the r emoval of foxes.

Recent studies in the Gibson Desert ofWestern Australia appear to confir m theseobservations (Christensen and Burr ows, inpress). Feral cat numbers incr eased fourfoldwhen fox control was initiated whilst ther ewas no change in cat numbers in aneighbouring site where no fox contr ol wasundertaken.

‘Feral cat numbers mayincrease when foxes are

removed.’

The impact on native fauna of a foxmanagement program which eliminatesfoxes but favours other pr edators, such asferal cats, r equires more study. It needs tobe carefully considered in the developmentof a fox management strategy.

3.1.4 Evidence from areas lackingfoxes

Manipulative predator removal experiments,such as those discussed above, pr ovidestrong evidence that fox pr edation is a majorthreatening process for Australian nativefauna. In addition, ther e is considerablecircumstantial evidence that is consistentwith these experimental findings. In theabsence of the fox, ar eas such as the wettropics (Torresian Biogeographic Region),Tasmania, Kangaroo Island and numer oussmaller islands, appear to carry intact and


abundant faunas (Johnson et al. 1989). Thisis despite the pr esence of feral cats and otherimpacts such as significant habitat loss.Conversely, in the pr esence of the fox, ther eis a history of extinction and major changesin the distribution of surviving mammalspecies over wide ar eas of the Australiancontinent. Other factors, however , such asthe absence of rabbits in some ar eas, couldalso account for the curr ent abundance ofnative fauna in some ar eas free from foxes.

‘Predator removal studiesprovide strong evidence that

fox predation is a majorthreatening process forAustralian native fauna.’

3.1.5 Impact of foxes onreintroductions of nativefauna

In a r eview of attempts to r eintroducemacropod species in Australia (Short et al.1992), foxes were identified as a factor limitingthe success of seven out of ten mainland r ein-troductions. They also found that r eintro-ductions to islands and mainland sites whichhad predators such as foxes and cats, had asuccess rate of only 8%. In stark contrast, thesuccess rate of r eintroductions to island siteswhich had no pr edators was 82%. Per hapsthe most convincing example of fox pr edationpresented by these authors involved thereintroduction of Parma wallabies (Macropusparma) to a site at Robertson in easter n NewSouth Wales. A total of 45 animals wer ereleased (12 fitted with radio transmittercollars). Three weeks after translocation theheads and thoraxes of two wallabies, whichhad been buried by foxes, wer e found oneto two kilometr es from the point of r elease.Of the 26 car casses eventually recovered, 24were buried (typical caching behaviour offoxes). Within two months, no collar edanimals remained alive, and within thr eemonths all 45 wallabies ar e believed to havebeen taken by foxes.

Sharp (1992) identified several factorsaffecting attempts to r e-establish rufous hare-wallabies (Lagorchestes hirsutus) in the arid

zone. Foxes wer e implicated in the failur eto establish one colony, and feral cats wer eimplicated in another colony. Fir e causedthe loss of another population.

3.1.6 Impact on traditional lands

In the desert r egions, traditional Aboriginalliving patterns persisted well into the twentiethcentury. Burbidge and McKenzie (1989) haveshown that in the W estern Australian desertregions, mammal extinctions have beencommon and widespread. The disappearanceof many mammals coincided with the timethat Aborigines left the desert r egion.Burbidge and Mackenzie (1989) r eported thatfoxes did not become established in manyareas until after the mammals had gone. Theysuggested that the subsequent change in thefire regime as evidenced by an incr easedincidence of wide-scale wildfir es was a majorcause of the decline in those species. Theysuggest that in the absence of traditionalAboriginal burning practices, which in thepast generated habitat mosaics and a systemof fire breaks, the fauna was not only deprivedof essential habitat but also made mor evulnerable to predators.

Attempts to r e-establish rufous hare-wallabies into the desert r egions have beenthwarted principally by high levels ofpredation, foxes in one case, and feral catsin another (Sharp 1992). Reintr oductions ofsome semi-arid fauna ar e doomed to failwithout fox and feral cat management,although other factors such as appr opriatecover, food and other essential r esourcesno doubt ar e also important. However, thereis no ef fective method for wide-scalepredator control in the semi-arid r egion.Sustained poisoning of foxes in strategicareas is curr ently the only method that isknown to be ef fective.

3.1.7 Fox competition with nativefauna

Although the r ole of the fox as a pr edator ofwildlife is well r ecognised, there is littleknown about its impacts as a competitor .


3

Either competition or pr edation by foxescould threaten the viability of wildlifepopulations reduced by habitat loss and mod-ification. Morris (1992) suggests foxes maycompete with the chuditch or wester n quoll(Dasyurus geoffroii) for food in jarrah for estin Western Australia. Foxes can also pr ey onyoung chuditch. A pr eliminary unreplicatedtest suggested that poisoning foxes with 1080may allow chuditch to incr ease.

3.1.8 Environmentalconsequences of potentialrange expansion

The fox has the potential to expand its rangeto include Tasmania, Kangaroo Island andother islands with suitable habitat. W ere thisto occur it would pr obably have majordetrimental impacts on the native fauna ofthese islands, particularly in T asmania whereprobable consequences of fox pr edation areobvious for such pr ey species as the easter nquoll, bandicoots, bettong and gr oundparrot. Other consequences, such ascompetition between foxes and otherspecies, are less certain, but the fox couldbe a strong threat to the T asmanian devil.

‘If foxes were introduced toTasmania, Kangaroo Island or

other smaller islands theycould cause considerable

damage.’

There have been several unsuccessfulattempts to introduce the fox into T asmania(Statham and Mooney 1991). The origin of afox killed near Launceston in 1972 is stillunknown. It would be r elatively easy forpeople to make further attempts. All lar gerAustralian islands have r egular sea and airtraffic, making irresponsible, deliberate ef fortsat introduction almost inevitable in the longterm. Early detection would be unlikely inisolated locations.

Whether foxes could spr ead further northis uncertain. There are records of foxes in theKimberley region of Western Australia (Kingand Smith 1985) and an isolated populationexists on Killarney station in the Victoria River

district of the Norther n Territory (Wilson etal. 1992). The consequences for native faunaof these or other populations of foxesspreading more widely are unknown, butcould be significant.

3.1.9 The fox as a predator ofrabbits

Parer (1977), Wood (1980) and Newsomeet al. (1989) conclude that the fox, inconjunction with other pr edators, canrestrict rabbit populations under certaincircumstances. Pech et al. (1992) definedthese as being: ‘at low rabbit densities, foxesare capable of regulating rabbits, while athigh rabbit densities, rabbits escape frompredator regulation and foxes would nothave a significant impact on rabbitnumbers’.

‘Foxes are not effective atcontrolling rabbit numbers in

good seasons.’

This prediction fits the historical patter n.Foxes have been pr esent in Australia formore than a hundr ed years and during thisperiod rabbit plagues wer e commonplace.

If this model is corr ect, the fox may beviewed as beneficial by r educing thefrequency of rabbit outbr eaks, or byextending the interval between outbr eaksby restraining rabbit population gr owthrates. In essence, when rabbit densities ar elow, fox pr edation may under certain cir -cumstances limit rabbit population gr owth.

It may be concluded on the basis of thismodel that the fox is capable of exer cisinga measure of biological contr ol on the rabbitpopulations. However, the fox is not aneffective biocontrol agent, because it cannotprevent the build up of rabbit numbers asa result of favourable conditions, and it hasminimal impact at high rabbit densities. Theimportant question is whether the r ole thatfoxes play in rabbit contr ol outweighs thedamage foxes cause to native wildlife. Theanswer is likely to vary depending on r egionand cir cumstances. For example, inbroadacre cropping land and other ar eas


where there are few native wildlife speciessusceptible to fox pr edation, it may beadvantageous to maintain fox pr edatorypressure on rabbits by not using 1080poisoning to manage rabbits. It has beenclearly demonstrated that foxes ar e highlysusceptible to secondary poisoning fr omeating 1080-poisoned rabbits (Bir chfield1979; Christensen 1980; King et al. 1981;McIlroy and Gif ford 1991). It would benecessary to deter mine that susceptiblenative wildlife ar e not likely to be pr esent.

‘Foxes are highly susceptible tosecondary poisoning from

eating 1080-poisoned rabbits.’

Where native wildlife is at significant riskfrom fox predation, use of 1080 on rabbits tocause secondary poisoning of foxes may bewarranted, though its ef ficacy is uncertain.Christensen (1980) linked rabbit contr ol with1080 to an incr eased abundance in nativemarsupials in Western Australia. Conversely,when the use of 1080 was r educed followingthe introduction of the Eur opean rabbit fleain Western Australia, populations of nativemarsupials such as bettongs, wallabies andnumbats declined. A better understanding ofthe relationship between rabbits, foxes andferal cats and impact on native wildlife from

controlling rabbits with and without foxmanagement is r equired.

3.2 Economic impact

3.2.1 Harmful economic impacts

Within a few decades of their intr oduction,foxes were regarded as an agricultural pestas is evidenced by the numer ous bountyschemes in place ar ound the tur n of thecentury. Although records are lacking, it wascertainly predation upon newborn lambswhich quickly ear ned the fox a badreputation. Sheep, and especially lambs,being of r elatively small size and lackingaggression, are more prone to pr edatorattack than many other livestock species.Further, sheep management often involvesunsupervised grazing in lar ge holdings.Under these conditions, it is not surprisingthat high losses of lambs to pr edators areoften claimed. Even so, the r ole of the foxas a pr edator of otherwise viable lambs issubject to much contr oversy and furtherconclusive studies ar e required.

‘Soon after it was introduced,the fox was regarded as an

agricultural pest.’


3

Fox predation on lambs may be significant on some properties.Source: R. Knox, APB

Curiously, one of the first r eports of foxdamage in Australia r elated not to the animalitself but to the rather cavalier attitude ofsome early hunt clubs who, in the course ofpursuing their quarry, damaged the fencesand walls of early settlers (Rolls 1969).

In published studies the fox has histori -cally been perceived as an insignificantpredator of livestock (Fennessy 1966; Honeet al. 1981) and hence ther e has been littledevelopment of appropriate managementstrategies. This situation is beginning tochange, partly as a r esult of the fox’s curr enthigh profile as a pr edator of endanger ednative species, but also due to a newemphasis on intensive management and theprotection of stud flocks, plus the suddenwithdrawal of commercial fox harvestingoperations. Added to this is a pr omotedawareness of risks associated with foxinvolvement in the potential spr ead ofrabies. This elevated status of the fox as athreat to the agricultural community hasoccurred in the continuing absence ofconclusive data on fox damage and the costand benefits of management.

‘Ultrasound studies suggestthat fox predation on lambsmay be more important than

was previously believed.’

While there have been few publishedstudies which show foxes as significantpredators of lambs, general causes of lambmortality have been well studied (for exampleRowley 1970). These past surveys indicatedthat the biggest single factor in lamb lossesappeared to be associated with the birthprocess or as a r esult of poor mater nal care,with primary predation causing the death ofan otherwise healthy lamb being only ofminor significance. Rowley (1970) points outthat most of the important factors involved inpoor lambing percentages are inconspicu-ous, whereas damage inflicted by pr edatorsis usually highly visible, commonly leadingthe sheep-owner to over estimate theimportance of predators.

Dennis (1965b) showed that of 4417 deadlambs collected and inspected in W estern

Australia, only 2.7% would have survivedif a pr edator had not attacked; starvationaccounted for almost half of the mortalities.A similar study in New South W ales(McFarlane 1964) indicated that of some3000 lamb carcasses examined, almost halfwere mutilated by pr edators but a maximumof 9.7% actually died because of pr edatorattack. A pr oportion of the latter would havebeen weak or moribund lambs so that only2% of the total lamb cr op was assessed ashaving been killed by pr edators.

‘Rogue foxes can cause highlosses of otherwise viable

lambs.’

Not all lamb mortality studies dismisspredation as being of secondary significanceand in some situations, foxes and otherpredators can cause heavy losses (Moule1954; Smith 1964; T urner 1965; McDonald1966). However, these unusually high lossescan often be attributed to cir cumstancespeculiar to a single flock or a small ar ea ofcountry (Coman 1985). These include a highproportion of twinning, particular lines ofewes which exhibit poor mothering ability,and the pr oximity of optimal fox habitat.There is evidence that individual killer foxesbecome habituated to the killing of lambs(Rowley 1970). Such foxes can cause seriouslosses in individual flocks and both T urner(1965) and Moore et al. (1966) describe suchevents.

Studies in Australia show that fr eshlykilled livestock ar e an infr equent dietaryitem. However, feeding on carrion, notablysheep and lamb car casses is common,particularly in winter (Catling 1988). Forexample, Alexander et al. (1967) found thatthe main fox activity amongst lambingsheep was centr ed upon scavenging forfoetal membranes. Ther e were some timidattempts to attack live lambs but of 36 foxsightings in the flock, only one attack on alive lamb was r ecorded. Ewes wer egenerally undisturbed by the pr esence ofthe foxes. These findings wer e supportedby the study of Mann (1968) wher e theexclusion of foxes by fencing did not r educelamb mortality.


Nonetheless, many of these past investi -gations probably underestimate the r ole offoxes as pests in the sheep industry. Indietary studies, identification of soft tissuematerial from lamb carcasses is dif ficultunless wool is pr esent. It is also possiblethat many lambs ar e killed without beingeaten, or killed and cached, to be eaten lateras carrion.

‘Foxes can account for up to30% of lamb deaths in some

areas.’

Pregnancy diagnosis in ewes usingultrasound has become mor e common, andthe early data fr om these ultrasound studiessuggests that fox pr edation may be muchmore important than pr eviously believed.For example, a r ecent study at theRutherglen Research Institute, Victoria (J.Reeves, Rutherglen Research Institute,Victoria, pers. comm. 1993) indicated thatfoxes took 7% of all lambs pr eviouslyrecorded as foetuses pr esent in a flock of896 ewes. Importantly, many of the lambstaken were completely r emoved from thepaddock immediately after birth, andtherefore would not have been r ecordedusing conventional methods for estimatinglamb loss. While losses of this magnitudemay be insignificant to some graziers, theyare obviously important to br eeders ofvaluable stud stock. While the losses maybe insignificant at a r egional or nationallevel, the operation of r ogue foxes onindividual properties can sometimes causevery high losses of otherwise viable lambs.

In a recent study of fox pr edation onlambs in wester n New South Wales, Lugton(1993) presents data indicating a high lossof otherwise viable lambs to pr edators,principally foxes. Between 1985 and 1992Lugton observed lamb pr oduction and lamblosses on five pr operties. He also r eviewedinformation from other sources. On thebasis of his own studies and those of othersinvolved in sheep pr oductivity trials, Lugtonsuggests that in some sheep gr owing areas,predation may account for up to 30% of alllamb mortalities. He concludes that foxpredation has a lar ge impact in ar eas where

foxes are common and wher e lambing isearly in the season. High lamb losses canoccur where lambing is out of step with orisolated from neighbouring flocks.

There are a number of potential pr edatorsof lambs, including feral pigs, dingoes andfoxes. Predator wounds of lambs vary incharacteristics and it is often dif ficult toidentify the pr edator from the woundinflicted. Rowley (1970) pr oduced a usefulkey for identifying pr edators from woundson lambs. Taken in combination with thepost-mortem techniques developed byDennis (1965a) and others, an estimate canbe made of the damage caused by foxes inthe sheep industry. However , the techniquesrely on the r ecovery of all lambs killed byfoxes and, as explained above, this is notalways possible.

Although no quantitative studies havebeen undertaken, r ecent observations alsosuggest the fox is a pr edator of cattle (K.Smith, RLPB, Moss Vale, NSW, pers. comm.1994). Reported instances ar e sporadic andmostly restricted to small rural subdivisionson semi-urban fringes. When it occurs,however, the ef fect of fox pr edation issubstantial — calves dying as a dir ect resultof predation or cows having to be put downas a r esult of fox attacks during calving.

‘The fox is a legendary poultrythief, but poultry in intensive

farms are well protected fromfoxes.’

Losses of other far m livestock to foxesare probably not of economic significance,although the pr owess of the fox as a poultrythief is legendary. T oday, most commercialpoultry farming operations use intensive orbattery farming and the animals ar e generallywell protected. Usually it is the small backyar dpoultry flock which suf fers, but while of majorconcern to the individual operator , theselosses are not of serious economic signifi -cance. Foxes ar e also a significant pr oblemfor some commer cial emu and ostrich far ms.Fox predation on newbor n goat kids iscommon but the level of loss is not consider edsignificant at a national level. For high-value


3

commercial cashmere herds, however, lossesto individual enterprises due to fox pr edationon kids can be high.

Foxes can be a major nuisance tolandholders, especially ‘hobby’ or ‘weekend’farmers through loss of household or hobbystock. Loss of a few ducklings or a newbor ngoat kid can cause genuine distr ess toowners. There has been incr easing demandon vertebrate pest contr ol agencies to supplypoison baits for fox contr ol to pr event theselosses.

In summary, the r ole of the fox as apredator of livestock is not well understood,despite a number of studies of lamb mortality.The importance of fox pr edation on lambsas a cause of significant economic losses willvary from district to district and fr om time totime. While the mor e recent studies indicatethat foxes may be mor e important as alivestock predator than first thought, thelosses are probably lower than those causedby a combination of natural factors includingstarvation, mismothering, dystocia andadverse weather.

Further studies are required to assess theimportance of predation by foxes to lamblosses. Emphasis in these studies needs to beon examining possible links betweenpredation levels and a range of factorsincluding local density of foxes, r ole of otherpredators, the importance of killer foxes,proximity of flocks to heavy cover , flock sizeand duration of lambing, br eed of ewes,incidences of twinning, possible seasonaldifferences in predation pressure, and lambingshelter. Projects funded under the V ertebratePest Program (see Introduction) will providesubstantial information on the impact of foxeson livestock production.

There are no comprehensive data availableon the costs of fox contr ol in Australia. Themajor costs would be the pr eparation andfield delivery of poison baits (Section 7.5.2).

3.2.2 Ecotourism

An emerging issue associated with themanagement of fox damage in Australia is

the potential impact of fox pr edation uponthe aesthetic quality of fauna parks,wilderness areas and reserves. Because ofthe uniqueness of much of Australia’s fauna,those reserves, parks or wilder ness areas inwhich tourists ar e able to view uncommonor distinctive wildlife ar e a valuableresource, both in economic and aestheticterms.

There is no practical method for assessingthe economic impact of foxes on wildlifealthough it may be considerable, particu -larly for ecotourism. The inter est shown byinternational tourists towards Australia’sfauna such as kangar oos, koalas andpenguins, both in zoos and wildlife parksas well as in the wild, ar e an indication ofthe potential of this industry.

‘Where foxes are controlled inDryandra State Forest,

spotlight tours to view nativemammals are becoming

popular.’

In South Australia, the W arrawongSanctuary, run by Dr John W amsley, hasdemonstrated that native fauna — such aswallabies, potoroos, bettongs and bandicoots— protected by fox-proof enclosures canbe shown to the public by ‘display feeding’.Foxes and cats have been eliminated fr omwithin the park and a fox and cat-pr oof fenceerected and supplementary feedingprovided. Guided gr oups of visitors can viewa range of smaller native mammals in a semi-natural setting, which in other cir cumstanceswould rarely if ever be seen.

With fox management, ther e is potentialto display native mammals in the wild to areceptive public. For example, in DryandraState Forest spotlight tours of the for est arebecoming popular since the populationrecoveries of the numbat (a diur nal speciesnow seen fr equently), the bettong and thebrushtail possum. Thirty bettongs per hourare commonly seen. In Dryandra village, arustic collection of woodcutter dwellingsnow used as tourist lodgings, as many as 30wild bettongs can be seen near duskcongregating at the feeding site. It is possible


for a person to sit quietly amongst a groupof bettongs and watch them busily andnoisily foraging for scattered wheat grains.

Persistent control has greatly reduced thenumber of foxes on Phillip Island and theirlikely impact on little penguin (Eudyptulaminor) populations. For the period 1987–92,202 foxes were destroyed while in the sameperiod 499 penguins were identified ashaving been killed by foxes (M. Hayes,DCNR, Victoria, pers. comm. 1993). Althoughother factors such as pollution are probablymore important, the risk foxes pose to anestimated annual $50 million tourist industryis significant.

These examples demonstrate the potentialfor wildlife to attract tourists. National parksprovide an ideal venue for the touristindustry to exploit a worldwide interest inAustralia’s unique wildlife. In selected areas,fox management may allow reconstructionof some of the mammal fauna that formerlyexisted, provided other population-limitingfactors are not operating.

Ecotourism ventures may be an effectiveelement of an integrated approach tomanaging Australia’s endangered orvulnerable wildlife. By combining wildliferehabilitation programs with economicallyviable ecotourism ventures, income earnedcan be used to maintain or increase theprotected areas.

3.3 Resource value and use

In the past, Australia has been one of theworld’s most important exporters of foxpelts. Tables 4 and 5 show that the sale offox pelts can generate significant exportincome.

‘There is no evidence thatharvesting foxes for pelts had

a significant impact onreducing the damage they

cause.’

Unfortunately overseas demand fluctuateswidely, and although the industry flourishedin the first half of the last decade, prices

have since dropped considerably. Thisdecline is due to a number of factorsincluding the vagaries of fashion, increasedsupplies from other countries andcampaigns by the anti-fur lobby. The figuresin Table 5 represent only saleable pelts. Thetotal harvest of foxes in any one year wouldbe higher. As an example, in some years10–20% of foxes can have severe mange(B. Coman unpublished data). These peltsand an unknown percentage of pelts badlydamaged by bullets would not be sent tomarkets.

‘Low export prices for foxpelts has discouraged

commercial harvesting.’

The commercial harvest for fox pelts inAustralia occurs during autumn and winterin the south-east of the continent. The furindustry estimates that about 60% of foxpelts supplied to the trade comes from New


3

CountryCountryCountryCountryCountry Unit valueUnit valueUnit valueUnit valueUnit value NumberNumberNumberNumberNumber ValueValueValueValueValue

($A)($A)($A)($A)($A) of peltsof peltsof peltsof peltsof pelts ($A)($A)($A)($A)($A)

Australia 23.20 350 981 8 152 000

Canada 57.03 88 800 5 063 000

USA 57.03 445 630 25 414 000

Note: Australian figures refer to exports only; figures for other

countries include internal use. North American figures include

pelts from farmed foxes.

Table 4: Quantity and value of wild red foxpelts supplied during 1982–83 from the majorexporting countries involved (after Ramsay1994).

CalendarCalendarCalendarCalendarCalendar NumberNumberNumberNumberNumber UnitUnitUnitUnitUnit PercentagePercentagePercentagePercentagePercentage

yearyearyearyearyear ofofofofof peltspeltspeltspeltspelts valuevaluevaluevaluevalue usedusedusedusedused

auctionedauctionedauctionedauctionedauctioned ($A)($A)($A)($A)($A) locallylocallylocallylocallylocally

1986 109 271 22.23 18.4

1987 105 654 21.40 20.6

1988 101 982 9.80 17.8

1989 44 145 10.46 19.0

1990 56 427 8.39 9.6

Table 5: Number and value of raw fox peltsexported from Australia (after Ramsay 1994).


South Wales, 30% fr om Victoria and theremainder from South Australia. Most foxesare killed at night using high-power ed riflesin conjunction with power ful spotlights. Asmaller percentage is taken via fox drivesor the use of den dogs. The use of steel-jawed traps for commer cial hunting isuncommon.

The annual harvest of fox pelts varieswidely and usually r eflects the export price.This is shown in T able 5 where the totalnumber of fox pelts auctioned at theMelbourne market varied fr om 109 000 in1986 to 44 000 in 1989.

4. Rabies and foxes

Summary

Rabies is a major thr eat to Australia,particularly if it becomes established in wildfoxes. At present the two main foci of sylvaticrabies are in Western Europe and NorthAmerica, both characterised by a highincidence of the disease in fox populations(up to 85% of diagnosed cases). In these areasit is considered that in the absence of foxes,sylvatic rabies could not be maintained byother wild species. This is due to the highsusceptibility of foxes to rabies, and thebehaviour and structure of fox populationswhich ensure the disease is readily spreadand maintained. The two approachespresently employed to control fox rabies arepopulation reduction and vaccination. Inareas where rabies is endemic, eliminationof the disease through vaccination may bethe mor e economically, socially andscientifically acceptable. However, inAustralia, assuming initial distribution of thedisease is limited as is the number of vectorsinvolved, population reduction is seen as thebetter alternative. If rabies becameestablished in foxes, the distribution andabundance of the species in Australia wouldmake control operations a daunting if notimpossible task. Other wild host populationsincluding dingoes and bats could alsobecome involved, perhaps furthercomplicated by the as yet unknownsusceptibility of other native species. Theimplications of this scenario are that in thefirst instance, efforts should concentrate onpreventing the entry of rabies into Australiaand secondly, if it does, strategies should bein place to rapidly eliminate the disease atits point of introduction.

4.1 The disease

‘Rabies occurs on allcontinents except Australia

and Antarctica.’

Rabies occurs on all the continental landmasses with the exception of Australia andAntarctica (MacInnes 1987; Blancou 1988).

The only r eported instance of rabies inAustralia was in T asmania in 1867, a smalloutbreak which was quickly eradicated(Pullar and McIntosh 1954). Rabies is oneof the most fear ed of human infectiousdiseases due to the distr essing clinicalsymptoms, the inevitability of death oncesymptoms appear and the severity of pasttreatments. The number of people dyingfrom rabies worldwide is estimated atbetween 20 000 and 75 000 per year , whilethe number of people tr eated because ofexposure to rabid animals is between500000 and thr ee million (MacInnes 1987;Fenner et al. 1987; W andeler et al. 1988).

‘The only reported instance ofrabies in Australia was a

small outbreak in Tasmania in1867 which was quickly

eradicated.’

4.1.1 Description

The rabies virus belongs to a gr oup knownas the lyssaviruses within the familyRhabdoviridae. The disease, which principallyaffects the central nervous system, is thoughtto infect all species of mammal and is nearlyalways fatal (Kaplan et al. 1986). The mostcommon route for rabies transmission is by abite from a rabid animal. Rabies virus, like allother viruses, needs living host cells in orderto replicate and survive. The tissues of ananimal that has died fr om rabies lose theirinfectivity at a rate that varies with the initialvirus content and the envir onmental influence(Wandeler 1980).

‘Rabies transmission isusually by a bite from a rabid

animal.’

There are two main epidemiologicalcycles of rabies: urban, with the domesticdog as primary host; and sylvatic with oneor more wildlife vectors involved. Cases ofhuman rabies are relatively rare in developedcountries where the urban cycle has virtuallybeen eliminated.


4


4.1.2 Present worldwide status

Many rabies epidemics have been r ecorded,with the dog acting as the main host andprimary transmitter of the infection to man(Kaplan 1985). In developed countries, theadvent of cheap and ef fective rabiesvaccines (Sikes 1975) which allowed forlarge-scale vaccination campaigns, coupledwith the contr ol of stray dogs, haveeffectively eliminated the dog as a vectorof rabies between 1945 and 1960 (T ierkel1975). Urban rabies now occurs principallyin parts of Africa, the Indian subcontinent,South-East Asia, and Central and SouthAmerica where there are communitiesassociated with large numbers of unvacci -nated or stray dogs (Geering 1992).

Without the fox, it is doubtful that sylvaticrabies would occur over most of the geo-graphical range of the disease with thepossible exception of South-East Asia. Anumber of wildlife vectors ar e involved,although it is usually only one species whichis responsible for perpetuating the disease ina particular region (Geering 1992).

4.1.3 Fox rabies

At present the two main foci of sylvaticrabies are in Western Europe and NorthAmerica. The disease is both characterisedby a high incidence of rabies in foxpopulations, with up to 85% of diagnosedcases in all species (W andeler et al. 1974),and by the cyclic natur e of the disease. Thelatter is related to seasonal peaks in foxreproduction (Müller 1971). W ithout the fox,it is doubtful whether sylvatic rabies couldbe maintained by other wild species eithersingly or collectively (Lloyd 1980). Thewestward spread of rabies in Eur ope hasbeen at approximately 25–60 kilometres peryear (Moegle et al. 1974).

The fox rabies virus has several uniquecharacteristics including high rates ofinfection and viral excr etion and a lowfrequency of post-infection immunity. Theincubation period in various laboratorytrials has ranged between 4–181 days

(Wandeler 1980). An infected fox may notshow symptoms until a period of highstress such as dispersal, mating or birthwhich also happen to be the periods ofgreatest contact between foxes (T inline1988). Following incubation ther e is asymptomatic period, typically of 3–5 days,throughout which the virus is usuallysecreted (Sikes 1962). Despite a limitedamount of evidence it appears that thenumber of foxes encounter ed by a rabidfox would be the same as if it wer e healthy,and that the rate at which these contactsare made would be incr eased by theheightened act iv i ty of rabid foxes(Macdonald and Bacon 1982).

While the characteristics of rabies withinthe fox ensur e that it is per haps the mostsusceptible wild animal, the behaviour andstructure of fox populations also ensur ethat the disease is r eadily spr ead andmaintained. In particular, dispersal by sub-adult foxes is believed to be r esponsiblefor the autumn peak in the cases of foxrabies and for the long distance pr ogressionof the disease (T oma and Andral 1977;Artois and Andral 1980). During the matingseason (winter), males may also stray fr omtheir own territories in sear ch of br eedingopportunities. Territories vacated by thedeath or movement of a pr evious occupantcan be incorporated into adjacent, higherdensity territories (Macdonald 1980). Atother times of the year ther e is limitedbetween-territory contact (Macdonald andBacon 1982). This in tur n limits spread andslows down the pr ogression of rabies(Wandeler 1980). The high r eproductivecapacity of foxes coupled with thecontinual turnover of territories means thatareas affected by rabies will be r epopulatedin a r elatively short time, thus cr eating anew population of susceptible animals forthe next wave of the disease (T inline 1988).

Comprehensive reviews of the natur e andmode of action of rabies and the r ole ofwildlife in its transmission can be found inBaer (1991), Wandeler et al. (1974), Kaplanet al. (1986), Steck and W andeler (1980),Zimen (1980), Macdonald (1980), Bacon



4

(1985), MacInnes (1987), Campbell andCharlton (1988) and O’Brien and Berry (1992).

4.2 Management techniquesfor rabies control

The primary aim of rabies contr ol programsis to protect humans from infection and fr omeconomic loss (Wandeler 1988). This can beattained by a drastic r eduction in the foxpopulation or by mass immunisation of thehost species, principally foxes. In both casesthe aim is to r educe the number of susceptiblefoxes to below the thr eshold density of animalswhich is necessary to maintain rabies in thewild (Anderson et al. 1981). Epidemiologicalevidence from Europe suggests that thethreshold density lies in the range of 0.2–1.0foxes per squar e kilometre (Müller 1971; Bogelet al. 1976 and 1981; Steck and W andeler 1980;Macdonald 1980) with 1.0 being the mostfrequently quoted value (Anderson et al. 1981).

4.2.1 Rabies control in endemicareas

The current practice in Eur ope and NorthAmerica of treating fox rabies epidemics byoral vaccination is r elatively recent (Blackand Lawson 1970; Baer et al. 1971). Prior tothis, reducing fox density was consider edthe only option. This was based on thefollowing premises (Wandeler 1988):

• rabies always disappeared from areaswhere the disease itself and contr ol effortshad reduced the fox population density toa low level;

• rabies did not penetrate into r egions whichhad a tradition of small game huntingwhere foxes were considered a pest andsystematically destroyed; and

• areas with low carrying capacities for foxessuch as marshland and alps wer e barriersto rabies.

Traditional methods for r educing foxpopulations for rabies contr ol are trapping,shooting, gassing of dens and poisoning.

Their usefulness for stopping or slowingthe spread of rabies has been contr oversial.Zimen (1980) points out that the fluctua -tions in the incidence of rabies duringdisease outbreaks may equally be due tothe normal fluctuations in the incidence offox rabies rather than the ef forts to reducepopulation density. He concluded thatmortality of foxes caused by rabies faroutweighed all ef fects of human inducedfox mortality. Despite substantial ef forts inFrance, Germany, Poland and other partsof Europe, as well as North America,traditional control methods have failed tohalt the spr ead of fox rabies (Linhart 1960;Johnston and Beauregard 1969; Wandeleret al. 1974; T oma and Andral 1977;Macdonald 1980). Wandeler (1988) suggeststhat for the fox, human contr ol has longbeen the most important mortality factorand that foxes adapted well to this situation.This resilience to human contr ol, coupledwith the high r eproductive potential andcarrying capacity of foxes in rural and urbanenvironments, are the pr obable causes forthe failure of fox population r eductionefforts in halting the spr ead of rabies. Baconand Macdonald (1980) also ar gue that thekilling of foxes can be counterpr oductiveto rabies contr ol because the disruption tofox social systems r esults in a gr eater degreeof movement into new territories and anincrease in aggr essive contacts betweenfoxes.

4.2.2 Vaccination

The first field evaluation of oral vaccinationof foxes using attenuated (weak) vaccines wascarried out in Switzerland with chicken headsas bait (Steck et al. 1982). The trial wasconsidered successful with two subsequentrabies outbreaks halted and no evidence thatthe vaccine strain had become established inwild or domestic animals. Similar campaignsquickly followed in Belgium (Br ochier et al.1988), Germany (Wachendörfer et al. 1985;Schneider et al. 1985), France (Artois et al.1987), Italy, Luxembour g and Austria(Schneider et al. 1988) and in Canada(MacInnes et al. 1988; Johnston et al. 1988).


Recent advances in cloning and geneexpression have led to the development ofa new generation of rabies vaccines, therecombinant virus vaccines. The duration ofimmunity conferred by this r ecombinantvirus (a minimum of 12 months) corr espondsto the length of pr otection required for foxvaccination in the field (Schneider and Cox1988). More importantly, and unlike theattenuated strains, there is no evidence ofresidual rabies in a variety of non-tar getanimals (Rupprecht and Kieny 1988; W iktoret al. 1984). The first field applications ofrecombinant vaccine baits took place inBelgium (Pastoret et al. 1988; Br ochier et al.1991). Following the final distribution of bait,vaccine-induced immunity was evident in81% of the foxes sampled.

In south-eastern Ontario, rabies has his-torically shown peaks of incidence over a 3.5year cycle. The last such peak was in the firstquarter of 1986 (T inline 1988). However, sincethe aerial vaccine baiting of foxes, theincidence of rabies in foxes has declined toits lowest level in 30 years. Most of the caseswhich do occur ar e across the Ottawa Riverfrom Quebec, which is experiencing a majorrabies epizootic (R. Rosatte, Ontario Ministryof Natural Resources Rabies Unit, pers. comm.1994).

These trials indicate that the eventualeradication of sylvatic rabies in endemic ar easis possible, although the r esults still need tobe treated with caution. Anderson (1991)points out that in these latter trials (andsimilarly in nearly all pr evious evaluations ofwildlife vaccination campaigns) the experi -mental design failed to include comparablenon-treatment areas in which baits wer e notdistributed. This does not allow for the cyclicalnature of rabies in fox populations to be fullytaken into account in the trial r esults. Voigt(1987) also raised this pr oblem but acknowl-edges that in the contr ol of rabies a non-treatment area is generally not possible. Ther eis also a need to impr ove upon the low levelof immunisation achieved in juvenile animals.In the second baiting period of the trialsreported by Br ochier et al. (1991) which wasprior to dispersal, bait uptake by juvenile

foxes was only 49%. Anderson (1991) alsoconcludes that an overall immunisation of81% may be suf ficient to prevent the spr eadof rabies in low to moderate density foxpopulations (such as the two per squar ekilometre in these trials) but for higherdensities in the or der of four per squar ekilometre, a 90% coverage would benecessary to block transmission.

4.2.3 Baiting systems

Whichever strategy is applied, a bait incor -porating either a vaccine or a toxin needs tobe delivered to fox populations for thepurpose of rabies contr ol. Baits such as horsemeat, tallow and chicken heads have longbeen used in fox contr ol, mostly in associationwith poisons such as 1080 (sodium mono- flu-oroacetate) and strychnine. Oleyar andMcGinnes (1974) and Allen (1982) also usedground beef and pork coated in granulatedsugar to deliver chemosterilants to wild foxes.In Great Britain the pr esent Ministry ofAgriculture, Fisheries and Food (MAFF)recommendations for population r eductionin urban foxes in the event of a rabies outbreakis for the distribution of day-old chicks injectedwith a gelatine solution of strychnine (C.Cheeseman, MAFF, Great Britain, pers. comm.1993). With the relatively recent advent oforally administered rabies vaccines, thedevelopment of baits specifically for thispurpose has r eceived a great deal of attention.

4.3 Implications forAustralia

The risk of fox rabies ever being intr oducedto Australia is low. Rabies could only bebrought into the country via an infectedanimal, and with strict quarantine contr olsover legal imports, the major risk isobviously from smuggling or illegal landings(Garner 1992). Such imports may not berare, although the likelihood of a smuggledanimal becoming rabid is pr obably low andwith limited opportunities for it to be athreat to other animals (For man 1993). Thishowever does not pr eclude the possibleintroduction of sylvatic rabies to Australia.

The uncertainty of the origins of existingepizootics in Europe with the suggestionthat it was the r esult of adaptation of thecanine virus to foxes (Blancou 1985) alsoshows that the behaviour of a disease suchas rabies is not pr edictable. Finally there isthe even less likely event that rabies couldbe deliberately r eleased as was thr eatenedby terrorists in the United Kingdom in 1989(Wilson 1992).

‘The risk of fox rabies everbeing introduced into Australia

is low.’

Circumstances will deter mine whichapproach to rabies contr ol is selected. In ar easwhere rabies is alr eady endemic, eliminationof the disease thr ough vaccination may bemore economically, socially and scientificallyacceptable. However, population reductionis seen to be the better alter native where thedisease is pr esently absent such as in Australiaand Great Britain, assuming, of course, thatdetection of its intr oduction is rapid so thatdistribution is r estricted, as are the numberof carriers of the disease involved.Furthermore, should rabies be intr oduced toAustralia the use of vaccines would beprohibited until such time that evidence wasavailable of their safety in the Australianenvironment (AUSVETPLAN Disease Strategyfor Rabies 1991). Existing contingency plansfor the contr ol of fox rabies in Australiatherefore rely on population r eductiontechniques (AUSVETPLAN Emer gencyOperations Manual, W ild Canid and FelidControl 1991). These involve the aerial andground distribution of poison baits (1080,strychnine and cyanide) supported bytrapping, den fumigation, shooting, exclusionfencing and harbour destruction. Coman(1992) attempted to implement thesetechniques in simulated rabies outbr eaks inVictoria with limited success. This was partlydue to a lack of r esources which would notbe the case in the r eal event. However, therewere still obvious deficiencies in techniqueswhich require further development. Thefailure of a policy of population r eduction inendemic rabies areas similarly cannot bedisregarded.

If rabies became established in foxes, thedistribution and abundance of the speciesin Australia would make contr ol operationsa daunting if not impossible task. Other wildhost populations including dingoes and batscould also become involved, per haps furthercomplicated by the as yet unknown suscep-tibility of other native species. The implica-tions of this scenario ar e that in the firstinstance, rabies should not be allowed to enterAustralia and secondly, if it does, strategiesshould be in place to rapidly eliminate thedisease at its point of intr oduction.

Through the use of simulation models ofsylvatic rabies, Pech and Hone (1992) alsohighlight the need for ef ficient disease sur -veillance systems to be in place. Assumingrabies was first detected in foxes and thereporting rate of rabid foxes was the same asthat for Gr eat Britain, Bacon (1981) estimatedthat 100–200 foxes might contract rabies beforeauthorities could be 95% certain of beinginformed. Pech and Hone (1992) suggest thatthis may take 4–7 months fr om the time ofintroduction which might allow rabies tospread between 5–35 kilometr es from theinitial point of infection. The further the diseasespreads before it was detected the less likelythat existing fox contr ol methods wouldprevent rabies from becoming endemic.

4.4 Implications for foxmanagement

It is inappropriate to initiate lar ge-scale foxmanagement programs on the basis of exoticdisease risk alone. However , land managersshould be awar e of the r ole that the fox canplay in the spr ead and maintenance of rabiesif the disease was intr oduced to this country.In terms of understanding the likely behaviourof fox rabies in Australia which is essentialfor contingency planning, the gr eatestinformation gap r emains the accurateassessment of fox distribution and abundance.Similarly, we also know very little aboutachievable rates of population r eduction bypoison baiting, pr eferred baits for dif ferentenvironments or appropriate bait applicationtechniques.


4


5. Community attitudesaffecting foxmanagement

Summary

Perceptions of the fox as a pest depend verymuch on individual backgrounds and upondeep-seated historical perceptions of the foxas a ruthless and cunning exploiter. Theseperceptions can hinder development of arational approach to managing this animal.

Historically, the fox has been importantfor hunting, a tradition that remains inAustralia today with many hunt clubs andother, less formal methods for hunting foxes.It is unlikely that recreational hunting caneffectively control fox damage, althoughrecreational hunters may assist individuallandholders by removing problem animals.

There has been little attention to the animalwelfare aspects of fox management inAustralia. However, there can be no doubtthat some current control techniques causepain and suffering to the animal. The ethicsof hunting foxes with hounds or other dogsis beyond the scope of this strategy since thetechnique is not recognised as a method ofdamage control. Of the poisons used for foxcontrol in Australia, cyanide (currently usedonly experimentally) is probably the mosthumane and strychnine the least humane.Information on the humaneness of 1080 inmembers of the Canidae is equivocal but,because of the very high sensitivity of foxesto this poison, it has an advantage over theother two poisons used because of its relativetarget-specificity. Shooting with high-poweredrifles is a humane method of fox control, butthe use of rim-fire rifles and shotgunsincreases the risk of maiming and slow death.

5.1 Perceptions of the fox

Attitudes and policies towards foxes and theirmanagement are, almost certainly, colour edby historical perceptions of the animal. Atdifferent times in our history it has beenvariously regarded as a killer , a pest, a r ogue

possessed of inor dinate cunning, a har mlessor even beneficial component of the faunaand an honour ed object of the chase.

The idea of endowing animals with thecharacteristics, particularly the failings, ofhumans, and having them enact imaginarydramas which ridicule the faults of man hasbeen popular with writers as early as Aesopand as late as W alt Disney. Even in the bible,the fox is cast as being deceitful, ‘Oh Israel,thy prophets are like the foxes of the desert’(Ezekiel 13:4). This tr end can be tracedthrough history, per haps reaching its zenithin Medieval times when Reynard the foxbecame a popular story character .

Unfortunately, much of the mythassociated with such tales has becomeinstalled in what might be ter medcontemporary popular ecology in Australia,where foxes are seen as cunning and ruthlessexploiters of wildlife and smaller domesticlivestock species. As a r esult, it is oftendifficult to separate fact fr om opinion andopinion from myth. It has only been in thelast decade that scientific evidence r elatingto the ef fects of fox pr edation on Australianwildlife has been collected (Chapter 3).

‘The fox is variously regardedas a killer, a pest, a cunning

rogue, a harmless component ofthe fauna , or an honoured

object of the chase.’

There are a wide range of per ceptionsabout the economic impact of foxes. It isimportant that accurate infor mation on theimpact of foxes is obtained and commu-nicated to the general public and to landmanagers in particular, so that they canmake informed decisions concer ning theneed for fox management.

5.2 Sport hunting

5.2.1 Traditional hunting

The tradition of riding with hounds is onewhich early English colonists transferr ed toAustralia and, in fact, is the main r eason for



the introduction of the fox to this country(Chapter 1).

The f i rs t t rue hunt c lubs wer eestablished in the 1850s although theAdelaide Hunt dates back to 1842. It isdoubtful whether these early clubs huntedfoxes, the mor e likely quarry being nativespecies (Rolls 1969). Curr ently there are23 listed Hunt Clubs in Australia (Camer on-Kennedy 1991) but the sport appears tobe expanding. Al l s tates exceptQueensland and the Norther n Territoryhave established Hunt Clubs. This includesTasmania which is fox fr ee. The existenceof hunt clubs in fox-fr ee areas indicatesthat the hunt is essentially a socialinstitution and the pr esence of the quarryis of secondary importance.

Tradit ional fox hunting pr obablycontributes little to the management of foxdamage. Clubs see themselves primarily assporting and social or ganisations.

Unlike other for ms of r ecreational foxhunting (see below), hunting with horsesand hounds is highly or ganised andincludes a Hunt Committee, Master ofHounds and Field Master . Clubs usuallyhave strict rules and guidelines. The HuntClubs Association of V ictoria, for example,has a detailed code of rules for fox hunting(HCAV 1988).

5.2.2 Other forms of recreationalhunting

Battues or fox drives ar e still common insome rural communities. Her e, groups ofindividuals meet, generally on an infor malbasis, and use unar med beaters (often withdogs) to drive foxes into a waiting line ofguns. Usually it is only small ar eas of primefox cover that ar e treated.

‘Shooting of foxes, usually atnight with high-powered rifles,is a common sport in southern

Australia.’

Another common technique of foxhunting is the use of small terrier dogs toflush foxes fr om dens. Animals thus

dislodged are either killed with shotguns orcoursed with lar ge lurcher dogs.

Finally, the sport shooting of foxes,usually at night with high-power ed rifles, isa common recreational sport in many partsof southern Australia. Such shooting is alsothe main method employed in the harvestingof wild fox pelts, but many shooters willtake foxes by this technique without anyexpectation of commer cial gain fr om thesale of fox pelts.

In many districts, r ecreational shooterswith high-powered rifles are invited ontofarms just prior to or during the lambingseason. The r esultant localised reduction infox numbers may give some temporaryrespite to lamb pr edation losses.

Recreational fox hunting often r equiresspecialised firearms and ammunition. Inaddition, hunters undoubtedly contributein other ways to local and r egionaleconomies although the extent of this hasnot been estimated.

5.3 Animal welfare

5.3.1 General

Animal welfare groups aim to pr otect animalsfrom cruelty and impr oper exploitation,encourage the considerate tr eatment ofanimals, and denounce practices per ceivedas causing animals unnecessary str ess. TheAustralian and New Zealand Federation ofAnimal Societies (ANZFAS) accepts that fr omtime to time some feral animals may causeagricultural or envir onmental damage, andthat in these situations ther e is a case forpest control (ANZFAS 1990). However, theirview is that only humane methods conductedunder the supervision of r elevantgovernment authorities, and within soundlong-term population reduction programs, areacceptable.

The cruelty r elated to the use of variousfox control techniques r elies essentially onsubjective assessments. In fact, a cleardefinition of humaneness is dif ficult. The

5

authors have used the definition used inSection 3.3 of the Australian Code of Practicefor the Care and Use of Animals for ScientificPurposes — ‘Pain and distress cannot beevaluated easily in animals, and thereforeinvestigators must assume that animalsexperience pain in a manner similar tohumans’.

Generally speaking, the humaneness oftechniques associated with the managementof introduced pest species in Australia hasreceived little attention, with most emphasisbeing placed upon the methods used to cullnative species such as kangar oos andwallabies. The Sub-committee on AnimalWelfare of the Standing Committee onAgriculture and Resource Management hasproduced Codes of Practice for some feralanimals but not for pr edators (Sub-committeeon Animal Welfare 1991). Sometimes in thecase of the intr oduced predators, there is atendency to justify r elatively inhumane controltechniques on the basis that the pr edatorsthemselves inflict pain and suf fering on theirprey. This argument is commonly, but in theauthor’s opinion, wrongly used by somegraziers to justify the setting of steel-jawedtraps for wild dog contr ol.

Both the RSPCA Australia and ANZF AS arestrongly opposed to the hunting of animalsfor sport. In the case of vertebrate pests likethe fox, they r ecognise the need formanagement measures but oppose the useof non-specific baiting or the use of toxinswhich may cause suf fering (RSPCA 1985).

5.3.2 Riding with hounds andother forms of dog hunting

Since the use of dogs (with or withouthounds) cannot be r egarded as a methodof broadacre fox contr ol, it requires littlecomment in these guidelines. A detaileddefence of fox hunting has been pr eparedby the Hunt Clubs Association of V ictoria(HCAV 1988).

‘Hunting foxes with dogs ismore of a sport than a control

method.’

The use of small terriers as den dogs andlarger lurcher dogs for coursing foxes is,likewise, more of a sport rather than acontrol tool. In the case of den dogs, theterriers as well as the foxes often r eceivesevere bite wounds. Fighting between foxand terrier can often be pr olonged, and notall foxes bolt immediately fr om the den andinto the waiting guns. Similarly the use oflarger dogs for coursing foxes is question -able on animal welfar e grounds. Death ofthe downed fox can often take severalminutes, and again, the dogs themselvescan receive serious bite wounds.

5.3.3 Sport and commercialshooting

The humaneness of shooting as a contr oltechnique for foxes depends almost entir elyon the skill and judgement of the shooter .High-powered rifles of calibr es from .17 upto .243 ar e commonly used. Generally,shooting with high-power ed rifles is ahumane technique for fox destruction. Theserifles are generally fitted with power fultelescopic sights and ar e used for a stationarytarget only. Under these conditions, rapiddeath from head shots or chest shots isusual. In those few cases wher e the animalsare wounded rather than killed outright, themassive wounds caused by these high-velocity projectiles usually result in deathwithin a few minutes.

‘Skilled shooting with a high-powered rifle is generally ahumane technique for fox

destruction.’

The less power ful .22 calibre, rim-firerifles should not be used for fox contr olbecause of the gr eater risk of non-lethalwounding.

The humaneness of shooting foxes withshotguns rather than rifles is mor e difficultto judge. Her e, the weapons ar e mostcommonly used upon a running tar get, andthe opportunity for non-lethal wounding ismuch gr eater. Factors that af fect thehumaneness of the technique include the


5

size of shot used and the gauge of theshotgun, distance over which shot travels,skill of the operator , and pr esence orabsence of thick cover . In general ter ms,only 12-gauge weapons utilising heavy shot(No.2 or BB size) should be used at distancesof up to 35 metr es — suf ficiently close toallow deep penetration of the shot into thecritical lethal ar eas (brain, chest cavity).

5.3.4 Den fumigation

Although not widely used, the intr oductionof lethal gas into fox dens is sometimesused as a contr ol technique. Mostcommonly, the technique is used to destr oyyoung pups in br eeding dens. In Australiaonly two fumigants ar e used, chlor opicrin(trichloronitromethane) or phosphine gasgenerated from aluminium phosphide,although carbon monoxide cartridges ar ebeing considered for use as a mor e humanefumigant for den fumigation in V ictoria (C.Marks, DCNR, V ictoria, pers. comm. 1994).

Chloropicrin

This is a non-flammable and colourless liquidwhich vaporises slowly at r oom temperature(sea level) (Sexton 1983). It is a str ong sensoryirritant which causes pr ofuse watering of theeyes, nasal passages and intense irritation ofthe respiratory tract (Chapman and Johnson1925; TeSlaa et al. 1986). Chlor opicrin waswidely used during the First W orld War as achemical warfare agent (T imm 1983).

Measurement of sensory irritation hasbeen attempted in mice ( Mus domesticus) bymeasuring the decr ease in r espiration rateupon exposure to a sensory irritant (Alarie1981). A commonly used measur ement is theconcentration of an irritant which pr oducesa 50% decr ease in an animal’s r espirationrate (RD50) and this has been suggested asthe level of irritation which may r esult inrespiratory injury following r epeated orextensive exposure (Kane et al. 1979).

The RD 50 for mice when exposed tochloropicrin was found to be 7.98 ppm.Chronic exposure at this level for six hours

per day over five days pr oduced ulcerationand permanent damage to the r espiratorysystem (Buckley et al. 1984). T oxicity ofchloropicrin is primarily influenced by theeffects on the small and medium br onchiof the lung, with death r esulting fromrespiratory failure (Clayton and Clayton1981). The speed at which this will occurdepends upon the concentration of the gasand the exposur e time.

‘Chloropicrin causes extendedsuffering and is not a humane

control agent.’

Although no work has been publishedon the ef ficacy of chloropicrin as a fox denfumigant, some parallels might be expectedwith the use of this chemical in rabbitwarrens. Oliver and Blackshaw (1979)observed that chlor opicrin was unevenlydistributed in a rabbit warr en when it wasintroduced without a power fumigator , atparticular points in the warr en. The gas,being heavier than air , will sink and collectat low spots in the warr en. Concentrationsin these ar eas have been shown to build upto levels of 5 ppm in a few hours, causingthe rabbits to move to ar eas in the warr encontaining higher and mor e immediatelylethal concentrations of the gas.

Gleeson and Maguire (1957) suggestedthat chloropicrin has a delayed ef fect onrabbits which have been exposed to sub-lethal but acute doses. This was typicallyobserved in rabbits which escaped fr omfumigated warrens. These were sometimesfound to have died, appar ently from theeffects of the gas, some weeks after initialexposure. Similar r esults are likely in foxes.

In summary, chloropicrin is not a humaneagent for fox contr ol. The symptoms seenin live animals of other species and thepathological changes seen in autopsiedanimals suggest that some suf fering occursover periods of several hours or , in the caseof animals escaping fr om dens, possiblydays. Power fumigators, which quickly for cethe gas thr ough all parts of the den, mightdecrease the time to death, and ther eforethe duration of suf fering.

Den Fumigation

Applied Biotechnologies of Victoria in association with the Victorian Department of Conservation and Natural Resources has developed and had registered for national use, carbon monoxide fumigation cartridges for control of foxes in natal dens. The product is called DEN-CO-FUME. The product is usually combusted in natal dens during August to October when the cubs are in the natal den. If access is restricted or there is a chance of fire, the cartridge can be burnt in a steel combustion chamber that has a flexible steel pipe.

Phosphine (Hydrogen phosphide)

This is a colourless gas, about 20% heavierthan air, which is pr oduced by the action ofwater on aluminium or magnesiumphosphide. Because hydrogen phosphide isa highly flammable gas it is pr epared as a solidtablet with ammonium carbamate which will,upon generation of the phosphine, pr oducecarbon dioxide and ammonia and thus reducethe risk of gaseous combustion of thephosphine (Sexton 1983).

In humans, the gas does not appear tocause sensory irritation and is characterisedby a slight garlic-like odour . It is a systemicpoison which depresses the central nervoussystem and respiratory function (Sexton 1983).Inhibition of vital cell enzymes is pr obablycaused by the action of phosphine upon bonemarrow and organ tissues (Klimmer 1969).

In a concentration of 2000 ppm, the gasis rapidly lethal to humans in less than oneminute (Sexton 1983). At 400 ppm it is lethalto rabbits in 30 minutes (Jokote 1904, quotedin Oliver and Blackshaw 1979). Unlikechloropicrin, chronic exposure at low levels(1–2.5 ppm for over thr ee weeks) gives noevidence of subacute or chr onic poisoning(Klimmer 1969).

Oliver and Blackshaw (1979) found thatrabbits could remain immobile during lethalexposures, indicating that the chemical is nota sensory irritant to them. The actual painand suffering caused in rabbits is not known,but in humans the symptoms often includenausea, abdominal pain, headache andconvulsions with ensuing coma (World HealthOrganisation, undated).

Oliver and Blackshaw (1979) measur edphosphine gas concentrations in rabbitwarrens following the administration ofaluminium phosphide tablets. Their r esultssuggest that the time taken to achievemaximum gas concentration in the warr encan be many hours and that it is lar gelygoverned by the availability of moistur e.

In summary, it is concluded that phosphineis more humane than chlor opicrin. Again,the length of suf fering or discomfort depends

upon gas concentrations in the dens and,under moist conditions with ample tabletsused, the time to death may be short.

5.3.5 Trapping — steel-jawed andsnare

Steel- jawed trapping is now usedinfrequently for fox contr ol in Australia. Veryoften, where foxes are caught in steel-jawedtraps, they ar e set for other species,especially wild dogs and rabbits. Themethod is clearly inhumane and it is of littlevalue as a contr ol technique, being timeconsuming and r elatively non-specific. It isdesirable that steel-jawed traps for foxcontrol be either banned or r estricted inthose states and territories wher e suchtrapping is still allowed.

Although there is a diverse range ofmechanical trapping devices used to r eplacethe standard leg-hold, steel-jawed trap,none of these has been specifically designedfor foxes. As an example, six designs ofspring traps have been appr oved by theMinistry of Agricultur e, Fisheries and Foodin the United Kingdom for use on specifiedmammals but none of these ar e suitablefor the taking of foxes (Bateman 1982). Asoft catch trap (V ictor Oneida, USA) hasbeen extensively investigated, used andrecommended in the USA, wher e it isregarded as both ef fective and humane.

‘Steel-jawed traps areinhumane and are not effective

for fox control.’

The soft catch trap has been usedextensively in New South W ales as part of amajor research program on fox ecology andthe effects of imposed sterility (McIlr oy et al.1994). In one continuous period of sevenmonths, a total of appr oximately 14000 trapnights produced a trapping success of onefox per 150 trap nights (Kay et al. 1995). Softcatch traps have also been used with somesuccess to catch dingoes in Queensland.

In Victoria, a leg-hold snar e trap initiallydesigned to r eplace the earlier gin trap forwild dog control, is ef fective for capture of


foxes. The device uses a snar e thrower whichtightens a thick but pliable wir e noose aroundthe animal’s leg. While this device causes lessbone and tissue damage than the steel-jawedtrap, some str ess is involved and fr equentinspection of snar e lines is r equired to preventsuffering in captured animals. The trap isregarded by the RSPCA, V ictoria as a mor ehumane alternative to the steel-jawed trap (P .Barber, RSPCA, Victoria, pers. comm. 1992)and is per haps the only technique curr entlyavailable for the selective r emoval of foxesin urban ar eas. However, setting of thesesnares is time consuming and a r elativelyinefficient method for lar ge-scale control. Itis recommended for use only in localised,semi-urban and urban situations wher e otherconventional means of contr ol, such asshooting and poisoning, cannot be used. Theirhumane use depends on fr equent inspectionand clearance, and until standar ds for this ar eestablished and enforced, they ar e likely tobe unacceptable on animal welfar e grounds.

5.3.6 Poisoning

Sodium mono-fluoroacetate (1080)

Sodium mono-fluoroacetate (1080) inhibitscitrate and succinate metabolism in thetricarboxylic acid cycle by the for mation offluorocitrate. The inhibition by fluor ocitrateis thought to be primarily r esponsible forthe toxicity of 1080 (Atzert 1971). However ,Kun (1982) has conducted experimentswhich suggest that 1080 has other modes ofaction in the mitochondria.

Irrespective of the exact mode of action,the end r esult is a loss of ener gy, anaccumulation of fluor ocitrate in body cellsand a disturbance of central nervous systemactivity and heart function. Death r esultsfrom progressive depression of the centralnervous system, ending with either cardiacfailure or convulsive r espiratory arrest asthe terminal event.

The toxicity of 1080 varies markedly indifferent animal classes and even betweenand within genera. Generally, cold-bloodedvertebrates are more tolerant than war m-

blooded ones, herbivor es more tolerantthan carnivores, and bir ds less af fected thanmammals. The LD 50 for mammals variesbetween 0.1 milligrams per kilogram and10milligrams per kilogram, with foxes beingamongst the most susceptible.

‘1080 is relatively target-specific with foxes being highly

susceptible to the poison.’

There is no detailed study of 1080poisoning of foxes, but general observationssuggest that the symptoms exhibited ar esimilar to those seen in dogs (L. Staples,Applied Biotechnologies, V ictoria, pers.comm. 1992). In this species, Chenowith andGilman (1946) describe a latent period ofone to two hours during which the animalis apparently normal. The onset of centralnervous system stimulation is shown bysudden appearance of hyper -excitability, theanimal running about and vocalisingvigorously. Within a few minutes, hyper -excitability gives way to convulsions. Barkingand panting persist during the convulsiveperiod which may last for up to two hoursand end in r espiratory failure. It is significantthat anaesthetised animals still showevidence of extr eme central nervous systemstimulation so that the behaviour of theanimal does not necessarily indicate extr emepain or suf fering. On this basis, it is dif ficultto draw any conclusions r egarding thedegree of suf fering experienced by foxespoisoned with 1080.

ANZFAS is opposed to the use of 1080,particularly for car nivores and omnivor es,preferring that cyanide be used if r esearchfinds it to be suitable. However , there is astrong view that 1080 is the most suitablepoison presently available for widespr eadfox management. It is r elatively target-specific with foxes being highly susceptibleto the poison. It is especially useful inWestern Australia and other r egions wherenative fauna ar e relatively tolerant to it dueto the natural occurr ence of 1080 in theenvironment. Studies have also shown thatit rapidly degrades in water and soil. It alsoshows no significant, long-ter m accu-mulation in body tissues (Eason 1992).


5

Strychnine

Strychnine is an indole alkaloid derived fr omthe seeds of the South-East Asian plantStrychnos nux vomica. The LD 50 forstrychnine in tested species varies fr om 0.5–3milligrams per kilogram, with members of theCanidae family being among the mor esusceptible species. Strychnine acts upon thecentral nervous system and essentiallyprevents normal functioning of muscle tissue.The earliest signs of poisoning ar enervousness, tenseness and pr ogressivelydeveloping stiffness. Violent tetanic spasmsmay occur spontaneously or be initiated byvarious stimuli such as touch, sound orsudden bright light. The animal finds itimpossible to stand, and falls rigidly to its sidewith legs stiff and outstretched, neck and backarched, ears erect and the lips pulled backfrom the teeth. Initially the spasms ar e inter-mittent, but they soon become mor e frequent.Spasms become continuous and death r esultsfrom spasms of the diaphragm and asphyxia,usually within an hour of the start of clinicalsigns (Seawright 1989). In July 1991, aWorking Group of the National ConsultativeCommittee on Animal Welfare recommendedthat the sale and use of strychnine be bannedin Australia (Department of Primary Industriesand Energy 1992).

Cyanide

Cyanide inhibits oxidative enzyme systemsand causes death fr om anoxia. Acutecyanide intoxication is characterised byrapid, deep breathing; irregular, weak pulse;salivation; muscular twitching and spasms;staggering gait; coma; and death (Seawright1989). The cyanides ar e particularly rapidin their action and death usually occurs fr oma few minutes to an hour after the onset ofclinical signs. The clinical course will occupyonly a few minutes in the most acute cases(Jubb et al. 1985). Even with subacute doses,the course of intoxication rar ely exceeds 45minutes and most animals that live for twohours after the onset of signs will r ecover.

Cyanide has been used experimentallyin Australia for fox contr ol and has the

advantage of pr oducing rapid death so thatfox carcasses can be r etrieved for inspection.Either potassium or sodium cyanide can beused and the chemical is nor mally encap-sulated in wax to pr event premature decom-position in baits (Section 7.5.2).

Because of its rapid action cyanide canbe considered as a humane poison. Its usefor routine fox baiting r equires further inves -tigation, particularly in the methods of pr e-sentation and the likely impact on non-tar getfauna. Because cyanide salts decomposerapidly in the pr esence of moistur e toproduce hydrogen cyanide, ther e areproblems of user safety which will r equirecareful investigation.

5.4 Implications of foxharvesting for damagecontrol

Despite a considerable harvest rate in someyears, there is no evidence that this rate ofremoval had a significant impact upon thelevel of damage caused by foxes. Thiscontrasts with the view of many landholdersand hunters that since the decline in fox peltprices, the density of foxes has risen sharplyas has the damage they cause. Theperception of incr eased risk of fox damagesince the decline in pelt prices is supportedby the figur es for the amount of 1080 poisonused for fox contr ol in some ar eas. As anexample, Figure 12 shows the dramaticincrease in use of fox baits in New SouthWales during the second half of the lastdecade (J. Thompson, Department of Lands,Queensland, pers. comm. 1994). However ,this might also r eflect, in part, an incr easein livestock commodity prices, an incr easein the numbers of livestock vulnerable toattack, and changes to r egulations governingthe use of fox baits (Thompson et al. 1991).The recent concerns about fox pr edationon wildlife (Section 3.1) may also havecontributed.

There was no decline in the high take offoxes in the mid-1980s as might have beenexpected if the harvest was having asignificant impact on fox density (T able 5).



5

Gra

ms

of 1

080

App

roxi

mat

e nu

mbe

r of

bai

ts (

'000

)

0 0

50

100

150

200

250

300

350

400

1980 81 82 83 84 85 86 87

Year

88 89 90 91 92 93

500

1000

1500

2000

2500

Figure 12: The quantity of 1080 and the number of baits used for fox contr ol in New South W alesbetween 1980 and 1993 (updated fr om Thompson et al. 1991).

However, it is not clear whether theharvesting during this time r epresented aconstant catch-effort each year or whetherthe areas of land hunted for foxes variedfrom year to year .

At best, commer cial harvesting providesonly sporadic r elief from fox damage sincethe level of hunting activity r eflects thehighly variable r eturn from pelt sales.


6. Past and currentmanagement

Summary

Historically, management of fox damage inAustralia has relied on the payment ofbounties, coupled with a range of controltechniques including shooting, poisoningand trapping. The fox is widely regardedas an agricultural pest although lessemphasis is placed on its managementcompared with other pests such as the rabbitand feral pig. In most states and territories,legislative provisions require the control offoxes by landholders; these are rarely if everenforced.

Although there is a growing awarenessby conservation authorities of the environ-mental impact of foxes, without the activeparticipation of the agricultural community,effective fox management over large areaswill not be possible. At present, most foxcontrol programs are either initiated toprotect enterprises at critical times of theyear such as at lambing, or to enhancesurvival of native species through reducedfox predation rates. Government agenciesmostly recommend the use of poisons(strychnine or 1080) to reduce foxpopulations with other options includingshooting, trapping, fumigation oradjustments to farming practices.Coordinated management programsinvolving several properties, and whereapplicable a range of land uses, isuncommon despite receiving a higher profilein recent times. No systematic evaluationof these programs or of individual controloperations has been undertaken except inWestern Australia.

6.1 History

Historically, a range of managementtechniques has been used to try and managefox damage. These include hunting;shooting; poisoning with strychnine, cyanideand 1080; and fox drives. These techniquesare outlined in Chapter 7. During the 1980s,

foxes were extensively hunted for their pelts,but as discussed in Section 3.3, evidencesuggests that this was mer ely a harvest anddid little to r educe overall fox density.However in its defence, many landholdersbelieve that ther e has been an incr ease infox damage associated with the decline ofthe commercial fox take. Ther e is no quan -tifiable assessment of the extent of damage.

6.1.1 Bounty systems

The payment of a bounty or bonus uponpresenting proof of the destruction of a pestanimal has been fr equently used againstfoxes (Rolls 1969; Lloyd 1980; Whitehouse1977). Bounties wer e first of fered in 1893,some 20 years after foxes wer e firstintroduced to Australia (Rolls 1969). InWestern Australia, bounties wer e paidduring 1928–56 (Gooding 1955). Figur e 13presents the data fr om the scheme as a plotof the number of fox scalps submitted forpayment against time (years). Fr om theupward trend in the number of scalps it canbe implied that the bounty scheme had littleimpact on fox numbers. Indeed, conven -tional bounty systems have been shown tobe an inef fective form of pr edator control.The reasons for this ar e numerous (Smith1990) and include fraudulent practices,failure to provide long-term relief from pestimpact, high costs, and selective r emoval ofsurplus animals. Often bounty hunters tar getthe area where pests are in gr eatest densityand most easily caught. This is usually notthe area where control is most needed(Whitehouse 1977).

‘Bounties have been ineffectivefor controlling foxes.’

Fairley (1968 quoted in Whitehouse 1977)comprehensively reviewed bounties as ameans for managing foxes in Norther nIreland. He concluded that bounties wer eineffective. Many of the foxes killed bypeople would have died of natural causes.Animals taken under bounty schemes ar eusually the young inexperienced animalswhich are yet to br eed. For example, halfthe dingoes caught ar e less than one year



6

old and 78% less than two years old(Whitehouse 1977). Just because lar genumbers of pests ar e killed does not meanthat the pest population declines.

6.2 Legislation andcoordination ofmanagement programs

Although the fox is r egarded as a pest speciesin all states and territories, ther e is lessemphasis placed on its managementcompared to some other vertebrate pests suchas the rabbit and feral pig. This may in partbe due to the per ception that foxes have littleimpact on agricultural pr oduction; a usual

prerequisite of an enfor ceable andwidespread management policy. Ther e is agrowing awareness by conservationauthorities of the envir onmental impact offoxes, and Western Australia in particular hasmade a significant investment in fox contr olto protect threatened mammals in several keyareas. Other states ar e investigating similaraction. For example, South Australia isstudying the ef fectiveness of fox managementto protect yellow-footed rock-wallabies in theNorth Flinders Ranges.

The value of fox pelts until r ecent timeswas also suf ficiently high that commer cialharvesting was seen as a cost-ef fectivemanagement strategy which in many ar eas

0

5 000

1928 1931 1934 1937 1940Year

1943 1946 1949 1952 1955

10 000

15 000

20 000

25 000

30 000

35 000

40 000

45 000

50 000

Bou

nty

paym

ents

($)

Figure 13: Bounty payments in Western Australia. The upwar d trend in payments demonstrates thatbounties are not an ef fective method of fox contr ol. If the system wer e effective a decline in paymentswould be evident (modified fr om Gooding 1955).

absolved the largest group of af fectedlandholders, the lamb pr oducers, from theneed to undertake their own contr ol.Although there are legislative provisions inmost states and territories to r equire themanagement of foxes by landholders, theseare rarely if ever enfor ced. Despite this,government agencies actively encourage foxmanagement through advisory, training andresearch services. In practice, foxmanagement is mostly r eactionary either toprotect enterprises at critical times of the yearsuch as lambing or kidding, or to enhancethe survival of native species thr ough reducedpredation rates. At the time of writing, theonly systematic evaluation of the ef fective-ness of fox management has been in W esternAustralia.

‘Fox control is theresponsibility of the landholder

— whether private orgovernment.’

The following is a summary of the pr esentlegislative status and management policyfor the fox thr oughout Australia. Thisincludes prescribed methods of contr olwhich in most cases involves the use ofpoisons. Because of their toxicity andpotential for misuse both to the detrimentof humans and non-tar get fauna, the use ofpoisons is normally regulated under stateand territory legislation. In all states andterritories, landholders and gover nmentagencies also have the option of using othermanagement techniques such as shooting,trapping, exclusion fencing, fumigation, oradjustments to farming practices. While moststate authorities issue advisory notes onthese techniques, their use is gover ned byother less specific legislation such as fir earmor animal welfare acts.

‘Because of their toxicity andpotential for misuse, the use of

poisons is regulated bylegislation.’

6.2.1 CommonwealthGovernment (AustralianNature ConservationAgency)

The Commonwealth Gover nment is involvedin the management of feral animals dir ectlythrough its r esponsibilities as a manager ofCommonwealth lands, and indir ectly throughits responsibilities under the EndangeredSpecies Protection Act 1992. Under this Act,administered by the Australian Natur eConservation Agency (ANCA), foxes havebeen listed as a key thr eatening process.Accordingly, there is a r esponsibility toprepare a Threat Abatement Plan for theimpact of foxes on endanger ed or vulnerablespecies, and to ensur e its implementationwithin areas of Commonwealth r esponsi-bility.

6.2.2 Northern Territory(Conservation Commissionof the Northern Territory)

The fox is classed as a pest under theTerritory Parks and Wildlife ConservationAct 1988. Unless a pest contr ol area isdeclared for the fox, ther e is no obligationon a landholder to take action. At pr esent,foxes are only managed in ar eas whereendangered species r elease programs arebeing conducted. In most of these cases,conventional 1080 baiting is used (Section7.5.2). There is virtually no dir ect landholderinvolvement in fox contr ol although somefoxes are poisoned as a r esult of dingobaiting operations.

6.2.3 Western Australia(Agriculture ProtectionBoard)

The fox is a declar ed animal under theAgriculture and Related ResourcesProtection Act 1976. They can only beimported or kept under high-securityconditions, and their numbers in the wildare r equired to be contr olled. TheAgriculture Protection Board (APB) pr ovidesadvice to landholders for fox contr ol in

Name Change

Now: Environment Australia


6

response to r equests and will helpcoordinate district campaigns and supplybaits. Despite the fox being a declar edanimal under legislation, a managementpolicy is not actively enfor ced.

Baits made fr om beef crackle andcontaining either 1080 or strychnine maybe purchased from the APB by landholdersfor use in fox contr ol. Alter natively,manufactured dried meat baits containing1080 can be pur chased with the authorityof the APB, or landholders can make theirown baits with strychnine tablets or powder .For coordinated campaigns, APB DistrictOfficers will inject fr esh meat baits with1080 or insert a one-shot oat into a bait.Regulations specify pr ovisions relating tothe manufactur e, handling, storage,transport and authority for the use of 1080.Landholders are required to notify theoccupier of every adjacent pr operty of theintention to lay baits and the period andlocation of baiting prior to laying the baits.Recommendations govern the use of thesebaits on private land and include er ectionof signs, distance r estrictions for the layingof baits (such as in r elation to urban ar easor water storages), and tethering or buryingof baits. Other r ecommended managementtechniques ar e exclusion fencing,modification to animal husbandry such asshed lambing of valuable stock, trapping(steel-jaw and snar e), fumigation and dendestruction, and shooting.

The APB encourages and assists gr oupsof neighbouring landholders to participatein coordinated management campaigns.They also undertake a limited amount ofcontract poisoning on behalf of landholders.A more recent development has seen districtgroups of landholders or ganising foxshooting drives. The W estern AustralianDepartment of Conservation and LandManagement carries out fox contr olprograms on selected ar eas of land underits management. To date this work has beenprimarily for r esearch purposes, tar getingspecific areas and fauna species known orthought to be at risk fr om fox predation.The 1080 meat baits used ar e manufactured

and supplied by the APB. Results fr omresearch have r ecently led to the pr oductionof operational guidelines for fox contr ol.The guidelines detail r ecommendedprocedures for identifying the need for foxcontrol and planning, pr eparation andimplementation of 1080 baiting pr ograms.In 1990–91, 56 000 baits wer e supplied forthis purpose. From very crude estimates,the cost to APB of field involvement withfoxes in 1991–92 was appr oximately$250000 (M. Sexton, APB, WA, pers. comm.1992).

6.2.4 Australian Capital Territory(ACT Parks andConservation Service)

Foxes are an unprotected animal under theNature Conservation Act 1980. Foxes canbe taken or killed without a per mit.However, a per mit is r equired to keep, sell,import or export foxes. Routine foxmanagement is conducted withinTidbinbilla Nature Reserve to pr otect captivepopulations of waterbirds and smallmacropods. Fox control on agricultural landis undertaken by the landholder , primarilyby shooting although mor e recently Foxoffbaits have been used.

6.2.5 Queensland (Department ofLands, Land ProtectionBranch)

The fox is a declar ed animal under the RuralLands Protection Act 1985, and as such itis the duty of owners and occupiers of landto destroy it. However, the legislation is notenforced for foxes. Department of Landsfield of ficers provide advice and for maldirection for the contr ol of foxes thr oughoutQueensland. They also issue 1080 baits forfox control. Authorised contr ol officers mayuse strychnine baits to contr ol foxes, butthese baits cannot be issued to landholders.The use of strychnine is discouraged infavour of 1080. Meat baits ar e generally used.Landholders can pur chase strychnine fr ompharmacists following the issue of a per mitfrom the Health Department. Use of 1080

Name Change

Now: Environment ACT

Name Change

Now: Natural Resources

baits is regulated on private lands and theuser must abide by conditions of use r elatingto notifying neighbours, distance r estric-tions and erection of signs.

It is illegal to intr oduce, keep or sell foxesexcept where permits are issued for scientificor educational purposes. The fox isrecognised as a thr eat to agricultur e andmanagement programs operate thr oughoutthe state, particularly in coastal or sheepproducing areas. In national parks bor deringthe Queensland coast, foxes ar e believed tohave a significant impact on coastal nestingturtles, and annual contr ol campaigns ar econducted. Some fox contr ol may be carriedout as part of wild dog contr ol, particularlyin the southern part of the state.

Foxes are recognised as an incr easingproblem in urban ar eas and a significanteffort has been made to publicise thedetrimental impact of the species ondomestic and native animals. In additionto poisoning, trapping (using cage traps inurban areas) and shooting ar e alsorecommended as contr ol techniques.Coordinated management campaigns ar enot common and fox contr ol is usually inresponse to individual r equests forassistance.

6.2.6 Victoria (Department ofConservation and NaturalResources)

Foxes are declar ed vermin under theCatchment and Land Protection Act 1994,which establishes r esponsibility for theircontrol with owners and occupiers of land.Despite this, no notice has ever been issuedcompelling a landholder to contr ol foxes.Under the Act it is also an of fence for anyperson or institution to keep live foxes inVictoria without a per mit.

Where foxes ar e identified as being aproblem, the Department of Conservationand Natural Resources (DCNR) will issue1080 meat baits, pr eferably the manufac-tured Foxoff bait or alter natively cookedliver or similar. These must be used in

accordance with established r egulationsincluding use of pr escribed baits, buryingthe bait, distance r estrictions for the layingof baits such as in r elation to urban ar easor water storages, notif ication ofneighbours, and er ection of signs. Otherapproved control techniques are trapping(cage or tr eadle snare) and shooting. In thepast, there was no coor dination of foxmanagement on private lands. However ,this is changing in conjunction with thedevelopment of mass pr oduced, long shelf-life 1080 baits. DCNR is about to implementa series of coor dinated control campaignsusing these baits. These will be supportedby advice on how best to undertake foxmanagement. Main emphasis is placed onthe integration of contr ol techniques into apreventative management pr ogram beforethe fox becomes a pr oblem. For the year1991–92, DCNR allocated appr oximately$450 000 for fox contr ol on public land (R.Waters, DCNR, Victoria, pers. comm. 1992).

Recently DCNR initiated ‘Foxlotto’ whichis open to far mers, professional shootersand shooting clubs. This scheme is avariation of the bounty system. Uponpresenting a fox scalp or entir e pelt, shootersreceive a lottery ticket and enter a draw fora range of monthly and annual prizes. In1992, over 15 000 scalps wer e presentedunder this scheme, a quantity which appearsrelatively small compared to the 35 000 peltstaken from Victoria in 1986 (30% of the110000 total for Australia). Nevertheless,this scheme has potential to developawareness about fox damage and what canbe done to alleviate it.

On public land, coordinated managementcampaigns are carried out to pr otect a varietyof indigenous species fr om fox predation.These include little ter ns (Bairnsdale),penguins (Phillip Island and Port Campbell),eastern barred bandicoots (Hamilton andGellibrand Hill) and lyr ebirds (Sherbrooke).Fox predation on native wildlife is listed asa potentially thr eatening process under theprovisions of the Flora and FaunaGuarantee Act 1988. This r equires thedevelopment of an Action Plan which sets


out effective management techniques toprevent or overcome damage due to thisthreatening process.

6.2.7 South Australia (Animal andPlant Control Commission)

The fox is a pr oclaimed animal under class5a of the Animal and Plant Control Act1986. The Act pr ohibits the keeping,movement, sale and r elease of foxes. Otherprovisions require a landholder to contr olfoxes, although this pr ovision is not pr esentlyenforced.

The Animal and Plant Contr ol Commission(APCC) is r equired to develop, implementand advise on coor dinated programs for thecontrol of proclaimed animals. The fox isrecognised as a thr eat to both agricultur eand native wildlife, but until r ecently wasgiven low priority in comparison to otherpest animals.

Prior to 1993, strychnine was the onlypoison available for baiting foxes in SouthAustralia but has since been phased out infavour of 1080. The number of appr ovalsgiven to landholders for the pur chase ofstrychnine to control foxes and the associatednumber of baits pr epared by them between1985 and 1991 ar e presented in Table 6.The estimated yearly expenditur e on foxcontrol with strychnine by landholders andgovernment agencies in 1992 was $250 000(M. Williams, APCC, SA, pers. comm. 1992).

The amount of fox baiting carried out inSouth Australia has incr eased dramaticallysince the intr oduction of 1080. This isundoubtedly due in part to per ceptions thatfoxes may be having a mor e importanteffect on domestic stock and wildlife thanpreviously recognised, but is also a r esultof a gr eater emphasis on a gr oup approachto fox baiting. Gr oup participation throughexisting networks such as Landcar e hasencouraged many landholders to take partin large baiting campaigns. Bait materialscommonly used include injected meat, liver ,fish, fowl heads and eggs, and Foxof f man-ufactured baits.

6.2.8 New South Wales (NSWAgriculture)

The fox is not a declar ed noxious animalunder the Rural Lands Protection Act 1989having been deleted fr om the list in 1977.This was in r ecognition of the dif ficulty inenforcing a legislative r equirement to controlfoxes. Under proposed legislation (Non-Indigenous Animals Act), the fox will beplaced in category 5 which includes allanimals which are recognised as widespreadpests. There is no r estriction on the keeping,transport or sale of foxes in New SouthWales.

Despite this, the fox is consider ed asignificant agricultural and envir onmentalpest. In recognition of this, NSW Agricultur eand Rural Lands Pr otection Boards activelyparticipate in services aimed at assistinglandholders and other gover nment agenciesto control fox populations. Coor dinated foxcontrol pr ograms ar e encouraged,principally to better r egulate the use of toxicbaits and to r educe the threat to non-targetanimals. Because of this concer n, there havebeen recent amendments to the NationalParks and Wildlife Act 1974, which requiresa Fauna Impact Statement to r esolve conflictsbetween pest animal contr ol programs andthe potential impact of these on endanger edfauna (Korn et al. 1992).

Rural Lands Protection Boards issue 1080baits consisting of either manufactur ed baits,


6

Year Number of Baits(35 mg/bait)

1984–85 23 7711985–86 91 6291986–87 79 4001987–88 185 8291988–89 88 2861989–90 90 4861990–91 43 857

Table 6: Number of 35 milligram strychninebaits prepared for fox contr ol in South Australiain 1984–85 to 1990–91.

fowl heads, and 100 gram pieces of fr eshmeat or of fal for fox contr ol. Recently ther ehas been a consistent incr ease in the amountof 1080 used for fox contr ol in New SouthWales, rising from 57 grams in 1980 to 2000grams in 1993. This is equivalent to anincrease in the number of baits fr om approx-imately 2050 to 330 000 (Figur e 12).

Use of 1080 baits is r egulated and usersare required to abide by certain r equire-ments including distance r estrictions inrelation to human habitation, notification tothe public about use of poison, and er ectionof signs. No other poison is r egistered forfox control although there is believed to besignificant illegal use of various lethalchemicals such as phosdrin. The only otherrecommended control techniques ar eexclusion fencing, flock management andshooting.

6.2.9 Tasmania (Department ofEnvironment and LandManagement andDepartment of PrimaryIndustry and Fisheries)

The fox is a pr escribed creature under theNational Parks and Wildlife Act 1970 andvermin under the Vermin Destruction Act1950. Under these Acts it is an of fence tobring a fox into the state, keep one incaptivity or allow one to go at lar ge in thestate. Also the Vermin Destruction Actrequires land occupiers to suppr ess anddestroy vermin. All reported sightings ar einvestigated by the Parks and W ildlifeService and/or Department of PrimaryIndustry and Fisheries, initially by interview,and then if justified by field surveys. Thelast fox known to have been killed in thewild was a young vixen in 1973 which wasof unknown origin.



7

7. Techniques tomeasure and controlfox impact andabundance

Summary

Damage and abundance — A large rangeof native fauna are susceptible to foxpredation. Fox gut analysis provides anindication of species at potential risk, butnot the extent of predation pressure. Surveytechniques to identify the distribution andabundance of vulnerable species before andafter fox removal is the most reliable methodfor land managers to assess damage. It isimportant to be aware that factors otherthan fox predation may af fect preyabundance. Techniques for monitoring preydensity include pitfall and small mammaltraps, spotlight and animal track counts.

The major agricultural damage due tofoxes is lamb loss. However many otherfactors cause lamb loss including difficultbirth, poor mothering, cold exposure andpredation by other pests such as feral pigs.A guide is presented to help to distinguishbetween the various factors causing lambloss.

The primary aim of fox management isto protect native fauna or increase lambproduction. The success of fox managementshould be guided by direct measure of theseparameters. Sometimes, such as for scientificresearch, fox density needs to be estimated.Techniques include breeding den counts inearly summer, scent stations, track andspotlight counts.

Maps, from simple hand-drawn charts,to sophisticated geographic informationsystems, ar e useful for recording thedistribution and relative density of foxes andvulnerable pr ey in an area, and forplanning control.

Control techniques — Techniques includetrapping, shooting, poisoning, den fumigation,exclusion fencing and changed farmingpractices. Poisoning using 1080 is the most

suitable lethal technique. It can be madetarget-specific to foxes through choice of bait,strict control of 1080 content and baitplacement, for example by burying it. InWestern Australia, dried 1080 meat baits havebeen shown to be very effective for fox controland are likely to be in other parts of Australia.However before they are extensively usedelsewhere, the applicability, especially inrelation to non-target kills, needs to be assessed.

Research to develop an effective biocontrolagent to manage foxes offers some promise.However, it is breaking new ground and hasto address difficult scientific, technical andbiological problems. Consequently, theresearch must be considered high-risk andlong-term.

7.1 Introduction

‘The aim of fox managementshould be to reduce to an

acceptable level theagricultural and environmental

damage foxes cause.’

Techniques are described in this chapter forassessing fox impact as well as for planning,implementing and then monitoring theeffectiveness of management pr ograms.Details ar e pr ovided separately forenvironmental and agricultural situationswhere dif ferences in objectives andprocedures exist. Many of the techniquesdescribed in this chapter have beendeveloped and tested only in W esternAustralia where considerable ef forts havebeen placed on fox contr ol in recent years.In some cases this will r esult in strategieswhich are geographically specific, and thisneeds to be taken into account until similarwork is conducted in other parts ofAustralia. Land managers should car efullyassess the applicability of W estern Australiantechniques to other ar eas.

The principal objective of foxmanagement, where the need for contr ol isidentified, is to r emove or r educe to anacceptable level the damage foxes cause toproduction and conservation values.


7.2 Assessing impact

7.2.1 Introduction

Effective fox management r equires theextent of fox damage to be quantified eitheras lost agricultural pr oduction, or forconservation, the degr ee to which thepopulation of native animals is suppr essed.For some pest species such as the feral pig,where the relationship between pest densityand damage is known for some for ms ofdamage, indicators of abundance can be auseful correlate of impact. This corr elationis not known for foxes. In addition ther e isno simple, reliable technique for estimatingfox density for a range of habitat types andprey density. Consequently, this makeschanges in population parameters of thepotential prey species in r esponse topredator control the only r eliable methodfor estimating the extent of fox damage.

‘Accurate assessment of foxdamage allows management

strategies to be targeted moreeffectively.’

7.2.2 Environmental impactassessment

In Section 3.1 it is concluded that foxes ar emajor pests of wildlife over much of Australia.However, the extent of this impact has notbeen widely quantified. The few studieswhich exist are from restricted geographicregions and with only a few native species.Unfortunately, it may take many years toaccurately quantify the extent of fox damageto wildlife in which time mor e species maybe driven towards extinction. In the absenceof any clear evidence, the land manager mustassume adverse impact wher e foxes ar eknown to interact with populations ofsignificant or endangered native species,including a range of small to medium-sizedanimals such as gr ound-nesting birds,dasyurids, bandicoots, possums, smallerwallabies and rodents (Appendix A).

Initially, an indication of fox pr edationcan be identified by dir ect observation of

fox and pr ey interactions or by indir ectsurveys of fox food habits such as scat orstomach content analysis. These, however ,are not always an accurate indication ofpredation pressure on thr eatened species.More important would be to monitor thedistribution and abundance of native speciesusing established survey techniques suitableto Australian conditions. Cooperrider et al.(1986) provides details of a wide range oftechniques. Other techniques include thoserelating to soil plots and small mammaltrapping (Newsome and Catling 1979), birdcounts (Braithwaite et al. 1989), and inEnvironmental Impact Statements pr eparedby CSIRO Division of W ildlife and Ecology(for example Shodde et al. 1992), althoughthe latter, while excellent infor mation, arenot readily available.

‘Diet studies do not necessarilyreflect the impact of foxes on

prey populations.’

Survey techniques suited to dif ferentfaunal groups are as follows:

• Amphibians and reptiles– timed, random or set transect counts

(species can be identified by sight orcall)

– terrestrial pitfall or aquatic cage traps

• Mammals– grid trapping with spring-set box traps

or pitfall traps (small mammals)– wire cage traps (medium size mammals)– track counts on raked plots (medium to

large mammals)– set transect surveys, either walked, or

covered by vehicle or helicopter; usingspotlights or nightscopes at night (lar gemammals and arboreal mammals)

• Birds– mist nets– set transect surveys (species identified

by sight or call)– spotlight counts (nocturnal species)

If native animal populations ar e decliningor restricted to mar ginal habitats, based onreal or assumed prior infor mation, all factorswhich might be r esponsible need to be


7

considered. Causes other than fox pr edationmight include habitat fragmentation anddegradation, changes to fir e regime,competition with introduced species, diseaseor hunting. While this infor mation is beinggathered, an indication of the extent of foximpact may be gained thr ough changes in thedistribution and abundance of pr ey speciesfollowing the r emoval of foxes. Pr eliminaryinformation may be obtained by pilot contr olstudies, with suitable contr ols, which monitorthe responses of selected pr ey species. Theresults of such pilot studies would pr ovidean indication as to whether fox contr ol is avalid management strategy for the thr eatenedspecies.

7.2.3 Agricultural impactassessment

Introduction

The major agricultural impact due to foxesis pr edation of lambs (Section 3.2.1).Because the fox hunts mostly at night, dir ectobservations of them killing lambs ar e rare.There are also a number of other pr edatorswhich can be involved, including dingoes,wild dogs and feral pigs. Befor ecommencing a fox management pr ogram,it is necessary to establish that the fox isimplicated and is causing significanteconomic losses.

‘The major agricultural impactof foxes is predation on

newborn lambs.’

Lamb losses attributable to predationby foxes

To determine the extent of fox pr edationon lambs, it is necessary in the first instanceto determine the principal causes of lambloss. The following constraints on lambsurvival can be identified (Alexander 1984):

• dystocia or dif ficult birth which is r elatedto birth weight and pelvic size of the ewe.Lambs lost to this cause generally showevidence of haemorr hage in the centralnervous system;

• cold exposure which becomes appar entwhen large numbers of lambs die coincidentwith periods of adverse weather;

• starvation/mismothering due to factors suchas failure of the ewe to bond with her lambs,accidental separations after bonding, udderdefects and competition with litter mates.These can only be assessed by dir ectobservation;

• extremely high or low birth weights whichpredispose lambs to death fr om birth injury,cold exposure or starvation; and

• predation based on cir cumstantial evidencesuch as unexplained low lamb marking,presence of pr edators and car cassesshowing mutilation.

A decision tree can be used to deter minethe causes of lamb deaths (Figur e 14a). Ifpredation is suspected of being the majorfactor, and various potential pr edators arepresent, the impact of each species needsto be deter mined. The following signs ar euseful (Figure 14b; Rowley 1970; Anon1991):

• Was the lamb alive when attacked? Attackson live animals r esult in bleeding at thewound site, with subsequent clotting for mingdark haemorrhagic areas. Dead animals donot bleed. A lamb bor n alive shows a distinctblood clot at the exposed end of the umbilicalartery and a lamb bor n dead shows no clot.Whether the lamb had walked or not isindicated by whether hoof cover is wor n onthe soles of the feet (Figur e 14b [5]);

• If alive, was the lamb sick or healthy?Examination of the lungs will show a cleardifference between successful br eathing,light pink and healthy; compar ed to lungswhich have not been pr operly aerated beingdark and liverish in colour (Figur e 14b [4]).Lambs are bor n with protective, softmembranes covering the sole of the hooves(Figure 14b [5]). These are rapidly lost whenthey begin to walk. In nor mal lambs the fataround the heart and kidneys is fir m, whiteand lacking in obvious blood vessels. Whena lamb fails to feed these fat r eserves becomesoft, gelatinous and dark plum r ed in colour.


Figure 14: (a) Decision tree for deter mining the cause of lamb death (after Agricultur e ProtectionBoard, Western Australia 1990); (b) Observable indicators which can be used to help deter minethe cause of lamb death.

Have lamb carcasses

been eaten or mutilated?

Probably not killed by predator.

Probably born dead.

Has lamb

breathed? [4]

Has lamb

walked? [5]

Have fat reserves

been utilised? [6]

Is milk

present in intestine? [7]

No No

No No No

Probably born dead

or very weak.

No

Probably dead when attacked.

No

Probably starved.Yes

Probably starved.No

Any signs of

bleeding?

Probably viable when killed. Foxes or dogs likely

cause. [8]

Probably birds

of prey.

Probably feral pigs.

Probably not foxes.

Dingoes or dogs are indicated.

Have adult sheep been attacked or

severely injured? [1]

Has carcass been entirely eaten except for skin and

some bones? [2]

Has attack

been confined

to orifices? [3]

Yes

Yes

Yes

Yes

Yes

No

Yes YesYes

(a) Decision tree


7

[1] Severe neck wounds on adult sheepindicating dingo or wild dog attack.

Source: NSW Agriculture

[5] Foot of a still-born lamb with intact solemembrane (left) and foot from lamb that haswalked (right). Source: J. Plant, NSW Agriculture

[2] Extensive mutilation and consumption oflamb carcass indicating the possibility of feralpig predation. Source: Queensland RLPB

[6] Stifle (knee) joint showing breakdown ofbody fat (i.e. lamb has starved).

Source: J. Plant, NSW Agriculture

[3] Lamb with eye picked out by birds post–mortem. Source: J. Plant, NSW Agriculture

[7] Milk in small intestine of lamb that hassuckled (right); empty intestine of still-born orweak lamb (left). Source: J. Plant, NSW Agriculture

[4] Unexpanded, heavy, dark-red lung of a still-born lamb.


[8] Fine puncture marks in skin indicatingpossible fox predation.


(b) Observable indicators


Similarly, successful feeding is demonstrat -ed by milk in the stomach and gut (Figur e14b [7]); and

• What species of animal was responsiblefor the predation? Wounding by mammalsinvolves biting often with matchingpunctures on opposite sides of the limb ortrunk. The car cass is usually moved fr omthe site of death. Feeding by bir ds of pr eyis characteristically on the upper side only,at the site wher e the lamb died and usuallyinvolves attacks to the eyes, mouth, navel,nose and anus (Figure 14b [3]). Attacksby foxes (and dogs) ar e often characterisedby a large number of lambs killed ormutilated in the one night. When thisoccurs the majority of car casses are usuallyleft in the paddock. Depending on whatpart of the body is first attacked, typicallythe neck ar ea is crushed with evidence ofcanine puncture marks on the inside of thelamb skin or the muzzle of the lamb ismutilated or bitten of f. Puncture marks canbe used to dif ferentiate wild dog or dingoattacks from fox as the latter has a veryslender jaw (Figure 14b [8]). The distanceseparating the canine teeth on foxes (25–32mm) is considerably less than in most dogs(Lloyd 1980). Although the haemorr hageresulting from a broken neck will beobvious in post-mortem examination, thelesions resulting from bites in other ar easof the body may not show exter nally orinternally by ventral inspection. For con-firmation of fox or dog pr edation thecarcass needs to be fully skinned.

Assessing the extent of fox predation

As indicated above, diagnosis of fox pr edationis possible by examination of car casses. Insome situations where foxes ar e active inlambing paddocks few carcasses can be founddespite significant predation (Lugton 1987).It is dif ficult to accurately deter mine the fullextent of fox pr edation. Ultrasound foetalcounts to establish the maximum r eproduc-tive potential of the flock combined with anassessment of all causes of lamb loss includingdisease and mismothering is necessary. Thiswould be beyond the r esources and expertise

of most land managers, making it dif ficult todecide whether or not it is economicallyjustified to undertake fox management.

A rigorously designed experimentalassessment of the full impact of the fox onagricultural production is necessary. It shouldinclude the costs and benefits of fox contr ol(Section 10.2.1).

Land managers must make their own bestassessment of lamb pr edation by foxes basedon examination of car casses and considera-tion of all causes of lamb loss. Comparisonof production figures with similar ar eas wherethere is no known pr edation may also pr ovidea guide, although the influence of other factorssuch as weather and ram fertility also needto be taken into account.

As is the case for thr eatened native fauna(Section 7.2.2), it may be feasible to conductpilot studies to test the impact of foxes onlivestock by appr opriately designed regionalexperiments. Fox contr ol and non-treatmentsites would be necessary, and the r esultantlambing success would need to be measur ed.

7.3 Measuring foxabundance

7.3.1 Introduction

Abundance can be measur ed in three ways:as the number of animals in a population,as the number of animals per unit of ar ea(absolute density), and as the density of onepopulation relative to that of another (r elativedensity) (Caughley 1977). For an elusiveanimal such as the r ed fox, population sizeor absolute estimates of abundance ar edifficult to obtain and usually inaccurate. Inmost situations, estimates of r elativeabundance will be suf ficient for an initialcensus of the fox population and to thenevaluate the success or otherwise ofmanagement programs. Numerous censustechniques are available, the most usefulbeing discussed below. T echnique selectiondepends on the habitat and availableresources. Cyclical changes in fox densitiesassociated with prey abundance or disease

can further complicate estimates of foxdensity (Lindstrom 1980; Macdonald 1980).In instances wher e foxes were previouslythought to be absent (for example T asmania,Kangaroo Island, far north Australia) it maybe necessary to confir m sitings throughidentification of footprints, scats, hair , foxvocalisations etc. (see T riggs 1984; Newton-Fisher et al. 1993; Brunner and Coman 1974;Morrison 1981 for guidance).

‘Estimates of fox abundanceare difficult to obtain and

usually inaccurate.’

7.3.2 Breeding den counts

Breeding den counts is consider ed to bethe only accurate method to deter mine foxdensity, provided the size of family gr oupsand social organisation is known (T rewhellaet al. 1988). This technique is especiallyuseful in urban ar eas where householderscan help identify the location of all br eedingearths (Harris 1981; Page 1981), or inuniform rural habitats by systematicsearches (Insley 1977; Pelikan and V ackar1978; Coman et al. 1991). Dens ar e mostprominent in early summer when cubsbecome active, trampling the surr oundingarea and accumulating pr ey debris anddroppings around the entrance (Kolb 1982).

Aerial survey techniques can beemployed to identify br eeding earths in veryopen habitats (Sargeant et al. 1975). The dis-advantages of this technique ar e that in mosthabitats dens ar e difficult to locate or maybe confused with rabbit burr ows. Dens ar eoccupied annually for a limited time, makingthem useful only for measuring changes inthe population fr om one year to the next.

7.3.3 Relative density estimates

Estimates of r elative population densities canbe obtained by a variety of indir ect measures.These include the hunting indicator ofpopulation density or HIPD (W andeler et al.1974), used commonly in Eur ope to calculatethreshold densities for rabies transmission(Anderson et al. 1981). These estimates have

many inbuilt inaccuracies (Zimen 1980), par -ticularly that hunting r ecords are as muchdependent on hunting habits and intensityas on fox population density, and may under -estimate the fox population by 50–75% (Steckand Wandeler 1980).

Scent stations or track counts use chemicalattractants or baits placed r egularly at pointsalong established routes of travel (Roughtonand Sweeny 1982; Phillips 1982). Thepresence of fox tracks in a one-metr e circleof sifted dirt placed ar ound each scent stationis considered as a visit. This pr ocess isrepeated over three to five consecutive daysto calculate an index for the activity of foxes.

To the land manager wishing to gain someinitial understanding of fox distribution andabundance and the short-ter m effect of amanagement program, the most appr opriatetechnique is spotlight counting. Spotlightcounts can be particularly useful in the caseof open country (Newsome et al. 1989)where a large area is being consider ed forfox control. Foxes are counted at night fr oma vehicle with the aid of a spotlight. Forconsistency between counts and to gainmaximum access to foxes in the managementarea, fixed length transects should becarefully planned before commencing thesurvey. All foxes seen within a sear chdistance either side of the vehicle, say 100metres, are counted. This distance will varyaccording to sightability in dif ferent habitats.

A reliable index of the population sizewill require a minimum of thr ee counts onconsecutive nights. In order to gain aconsistent level of pr ecision, and whereresources permit, counts should be r epeateduntil they give similar indices. A rule ofthumb when deter mining the number ofcounts is for the standar d error of the countsto be within 10% of the mean. Possiblesources of variation between counts shouldbe kept as low as possible. For example,conducted by the same person, fr om thesame vehicle and height, travelling at thesame speed and close to the same time eachnight. Some caution should be attached tospotlight counts as they tend to be biasedtowards including naive younger animals.


7

Spotlight Counts

This technique should be used with caution. Studies by NSW Agriculture on the Central Tablelands cast doubt on the reliability of using spotlight counts to accurately assess changes in fox density.


7.3.4 Population manipulationindex

Absolute density can be derived fr om relativedensity estimates measured before and aftera known number of animals ar e removedfrom the population (Caughley 1977;Eberhardt 1982). This technique is useful indetermining the ef fectiveness of amanagement program. The only limitationsare:

• the number of foxes killed can be counted,for example, by spotlight shooting orcyanide baiting;

• the indices used befor e and after will notbe affected by the r emoval technique. Forexample spotlight counts of foxes afterspotlight shooting may be biased becauseof changes in behaviour of surviving foxes;

• the pre-removal index has a constant r ela-tionship to the initial population size asdoes the post-r emoval index;

• the period over which animals ar e removedis short; and

• the changes in indices and the number ofanimals removed is not small.

7.4 Use of fox impact anddensity measurements

7.4.1 Introduction

As with any pest species, achievement ofmanagement objectives is enhanced withthorough planning (Chapter 8). This isfacilitated by the r outine recording ofimpact assessments, mapping of r elevantinformation from the designated ar ea, andallocating action to r ealistic and prioritisedmanagement units.

7.4.2 Recording assessments

Because direct survey of the fox populationis difficult, and the r elationship between foxdensity and the level of impact is unknown,assessment of impact is best deter mined byevaluating the status of pr ey populations be

they native wildlife or lambs. The pr ocessof recording assessments is not necessarilyan aid to interpr etation but rather a way ofensuring that all the r elevant information isdocumented. It is also a way of ensuringthat information is recorded in a convenientform for transferring onto maps or com -puterised databases.

‘The relationship between foxdensity and impact is largely

unknown.’

7.4.3 Mapping

Maps can be of various types: simple hand-drawn charts, topographic maps, landsystem or land unit maps, aerialphotographs, or the sophistication ofinteractive computerised geographicinformation systems (GISs). The choicedepends on r esources, scale of the tr eatmentand the extent of the pr oblem.

‘Correlations between damageand fox habitat, will help

determine where foxmanagement needs to be

targeted.’

Assuming that little is known about the dis-tribution and abundance of foxes in the ar ea,maps are important for deter mining andrecording the relationships between variablesassociated with the distribution of pr ey speciesand features which will need to be identifiedin planning a fox management pr ogram.These will include tracks, trails, fence lines,lambing paddocks, r efuge habitats forendangered species, property boundaries,natural boundaries, corridors, dens and foxrefuges (Figure 15). Correlations betweendamage and habitat, wher e they can beidentified, will deter mine wher e foxmanagement needs to be tar geted. A lambingpaddock is an obvious example, howeverconservation problems are less clear. Therefuge habitat for an endanger ed species maynot necessarily be its pr eferred habitat, andthe one which will need to be tar geted ifthe species is to thrive. In these situationsmaps can be used to identify the distributionof both the r efuge and pr eferred habitats,

with efforts to remove foxes concentratedin each. Because foxes often depend onrabbits for food, mapping the distributionof warrens may also give some indication ofwhere to concentrate contr ol effort.

Several Landcare groups in Victoria andelsewhere are now involved in the pr oductionof customised maps of Landcar e districts andindividual far ms for a variety of landmanagement issues including pestmanagement. In one example, the initial basetopographic maps (scale 1:25 000) have beensupplied to Landcare groups in digitised for m.The groups share a single computer andsoftware package which allows for overlaysof information to be added to the maps. Theoriginal topographic map is then printed outin sections to corr espond with individualfarms or cooperatives. Landholders then assistin verifying the maps and adding infor mationsuch as the location of particular weedproblems or main ar eas of rabbit activity.Although foxes have not yet been includedin this inventory, it may be practical to map

all known fox br eeding dens within theLandcare area. This in tur n would allow fora coordinated program of fox den fumigationduring the br eeding season. Other possibili-ties include the r ecording of all fox poisoningtrails/sites during a coordinated baitingcampaign. Such r ecords depicted on mapsquickly indicate any gaps in the coverage ofa baiting program.

Computer-based mapping systems alsoinclude the facility for a database r elated tothe mapped areas. This then of fers the meansto keep highly accurate r ecords of controlinputs and outcomes as measur ed byreductions in damage or fox numbers (forexample spotlight transect counts). On abroader scale, GISs can be used to deter minecorrelations which might show, for example,where foxes potentially have their gr eatestimpact on endangered species. Wher e foximpact correlates highly with fox populationindices, changes over time in these indicescan be used to monitor the pr ogress of controloperations.


7

Figure 15: Example of a simple map of four hypothetical pr operties showing the key factors thatlandholders should r ecord and use to plan fox management.

D

D

D

D

Lamb paddockProperty A

Property C

Property B Internal tracks

Home paddocks

Scrub - fox refuge habbit

Rabbit infestation

Fences

Boundary

Fox dens

Property D


7.4.4 Allocating managementunits

The information collated on maps can beused to identify practical management units.Boundaries in the management unit will beevident from natural or artificial barriers orapparent changes in the distribution of pr eyspecies. An important dif ficulty which mustbe considered is the mobility of foxes. Thiscan negate ef forts to manage fox damagedue to neighbouring foxes moving intovacated territories. This will influence thesize of the management unit which is inturn influenced by the time-frame of themanagement program. For example,protecting a lambing paddock for onemonth will be a much smaller operationthan ensuring the long-ter m survival of anendangered species in a natur e reserve.

While the distribution and abundance offoxes in the management ar ea may not beknown, the size of management units basedon known figures for density and homerange for similar ar eas can be used as a guide(Chapter 2).

‘Past fox managementprograms have generally been

non-strategic anduncoordinated.’

In the past, fox management pr ograms,principally poisoning, have mainly beencarried out on small management units suchas an individual pr operty or natur e reserve,with little coordination. As the damagefoxes cause to native fauna has becomeevident, governments have incr easedinputs into planning and coordination offox management. In many cases it may benecessary to coordinate management offoxes on surrounding agricultural land, sayas a buf fer zone. The extent to which thiscoordination takes place will also influencethe size of management units.

7.4.5 Establishing priorities

Priority for treatment of management unitswill depend on a number of factorsincluding:

• type and value of pr ey species. For nativespecies it is their conservation status andtheir representativeness in other ar eas;

• severity of the damage;

• presence of and damage due to other pestsand other threatening processes;

• feasibility of reducing damage in time tosave the pr ey;

• size of the management unit;

• availability of appr opriate managementtechniques;

• availability of funds, time, labour andequipment both for immediate action andfor future sustained control;

• the ability to coordinate managementeffort; and

• the ability to pr event reinvasion by foxes.

7.5 Control techniques

7.5.1 Introduction

A variety of fox contr ol techniques ar e usedin Australia. These include hunting bytrapping and shooting, poisoning, dendestruction, exclusion by fencing, or changesto farming practices. In the case of agricul-tural protection, the methods used ar e mostlydetermined by the biology of the livestockbeing protected rather than the biology of thefox. As such, a variety of contr ol techniquesare employed on a r eactionary basis with littleconsideration for sustained r eduction of theiragricultural impact. This may be the r esultof the lack of suf ficient incentive and of cost-effective techniques.

‘Fox control techniques used inAustralia include trapping,

shooting, poisoning, dendestruction, fencing and

changes to farming practices.’

For wildlife conservation the issue ismuch clearer. Fox pr edation is a significantthreatening process to some wildlife specieswhich is alleviated by the management of



7

foxes. Apart fr om fencing and poisonedbaits, no other method has been tested andshown to be ef fective.

7.5.2 Poisoning

General

Poisoning foxes using a variety of toxins andbait types has long been consider ed to be themost ef fective method of fox contr ol.Strychnine was historically the r ecommendedpoison throughout Australia. Following theintroduction of 1080 for rabbit contr ol in the1950s, its ef fectiveness against canids was soonrealised and it became widely used for foxcontrol from the late 1960s.

The preparation of strychnine baits hasusually been the r esponsibility of landholdersoften with only general guidance: ‘as muchstrychnine as will thinly cover half an inch

on the small blade of a pocket knife is generallyaccepted as a lethal dose’ (New South WalesAgriculture memo 961). Baits included wholecarcasses (although this is not r ecommendedby state agencies), of fal, cubes of meat orfat, chicken heads, day-old chicks, butter ordripping. The use of 1080 is much mor etightly regulated. Only gover nment or semi-government agencies ar e allowed to handlethe poison and pr epare baits.

‘The use of 1080 baits for foxcontrol has risen dramatically

in recent years.’

The number of 1080 baits distributed inNew South Wales for fox contr ol has risendramatically from approximately 2000 in1980 to over 300 000 in 1994 (J. Thompson,Department of Lands, Queensland, pers.comm. 1994.). Thompson et al. (1991)concluded that this incr ease has been dueto a combination of factors including r educedhunting pressure resulting from the then highcommodity prices for wool and lambs.

‘The use of strychnine for foxcontrol is being phased out inpreference to 1080 which is

more target-specific and morehumane.’

The present requirements for fox poisoningin each state and territory ar e presented inTable 7. Restrictions on application r efer tothe laying of baits only, such as r equiringthem to be buried, and not on r equirementssuch as the display of war ning notices. Sincethe use of strychnine for fox contr ol is beingphased out in pr eference to the mor e target-specific, and probably more humane 1080,its use is not discussed in detail.

Sodium mono-fluoroacetate (1080)

Sodium mono-fluoroacetate or 1080 is thesynthetic sodium salt of the naturallyoccurring mono-fluoroacetic acid. It isodourless, virtually tasteless and highlysoluble in water. It is widely used in Australiafor vertebrate pest contr ol. Because of itstoxicity and importance to agriculturalproduction and nature conservation, by law

Warning signs are essential to notify people thatfox baits have been laid.

Source: Applied Biotechnologies

74 Managing Vertebrate Pests: Foxes74 Managing Vertebrate Pests: Foxes

1080 powder (usually about 96% pur e) canonly be obtained by gover nment or semi-government agencies which in tur n preparebait for use by land managers.

Fluoroacetate occurs naturally in anumber of Australian plants of the generaAcacia, Gastrolobium and Oxylobium(Oliver et al. 1977) some species of whichextend from south-west Western Australia,up through the Northern Territory and downinto the central highlands of Queensland(Everist 1947). This natural occurr encebenefits the use of 1080, particularly inWestern Australia where some native faunahave evolved tolerance to the toxin r elativeto the intr oduced fox which is highlysensitive (King et al. 1981; McIlr oy 1986;King and Kinnear 1991). For example,brushtail possums from Western Australiahave an LD50 of over 100 milligrams perkilogram, whereas possums fr om nearCanberra had an LD 50 of 0.68 milligrams perkilogram (King 1990).

The implication for south-easter nAustralia, where 1080 tolerance has notdeveloped, is that species such as the tigerquoll (Dasyurus maculatus) and othercarnivorous marsupials, and some r odentsand bir ds may be at risk fr om foxmanagement programs although this has notbeen demonstrated experimentally (McIlroy1992; McIlroy and Gif ford 1992; Kor n et al.1992). Despite these dif ferences in toleranceto 1080 within the Australian fauna, this toxinremains the best choice thr oughout thecontinent (McIlroy et al. 1986; McIlr oy andGifford 1992). With 1080, there is scope forincreasing target-specificity even in ar easwhere the fauna has not evolved tolerance.

Selectivity of poisoning can be enhancedby:

• using baits highly attractive to foxes;

• minimising poison content and maximisingbait size to achieve low 1080 concentra-tion in the bait;

• placing baits in the best ar eas to encounterfoxes; and

• burying baits.

The amount of 1080 r equired to kill a foxis about 0.15 milligrams per kilogram bodyweight (McIlroy and King 1990) via intraperi-toneal injection or stomach intubationroutes. As McIlr oy and King acknowledge,it does not allow for incomplete absorptionof 1080 fr om the gut when the toxin isdelivered via a bait, nor does it allow forany loss of toxicity due to leaching ormicrobial degradation after a bait has beenlaid.

Newsome and Coman (1989) r eport aweight range for adult foxes of 3.5–7.5kilograms for souther n Australia. Recentshot samples fr om the wheatbelt of W esternAustralia (Thomson unpub) r evealed amean weight for males of 5.67 kilograms;range 2.7–8.5 kilograms. The sample sizewas 374 and 8.3% weighed mor e than 7kilograms. Taking into account the heaviestfox sampled (8.5 kilograms) and based ona lethal dose of 1080 as 0.15 milligrams perkilogram, the minimum dose r equired is 1.3milligrams. For females the statistics wer e:N=351; mean=4.82 kilograms; range 3.0–7.0kilograms.

It is dif ficult to determine the absoluteminimal dose because the minimum lethaldose has not been deter mined using meatbaits and, per haps more importantly,because of the uncertainties surr oundingthe fate of 1080 in a bait after laying. McIlr oyand King (1990) r ecommend a minimumdose of 2.5 milligrams per bait. This amountshould be suf ficient to kill the lar gest foxsampled (8.5 kilograms), even if 50% of the1080 were lost due to leaching, micr obialdegradation or incomplete absorption. TheVertebrate Pests Committee nationalrecommended dose rate is 3 milligrams, andstates are encouraged to adopt this.

Staples et al. (1995) tested the lethal ef ficacyof 3.3 milligram 1080 Foxof f baits (see below)after storage (10–39°C) for 0.4, 7 or 11 monthsby giving a single bait to each of 6 female and8 male foxes (3.3–6.5 kilograms live weight).Efficacy was 100% r egardless of storage time.Mean time to first visible ef fect was 4.06 hoursand to death 4.68 hours and appear edindependent of weight or sex.


7A recent trial (D. King, APB, W A, pers.

comm. 1993) has shown that meat baitscontaining 2.5 milligrams of 1080 ar e fatal tofoxes weighing up to 4.2 kilograms. Thr eecaptive foxes (weights 3.0, 4.2, and 4.2kilograms), acclimatised to their surr oundingsand food, died after consuming a singlekangaroo meat bait of 120 grams, dried toapprox 50 grams. This supports the above r ec-ommendation of 2.5 milligrams, althoughfurther trials using lar ger foxes ar e needed toconfirm this.

Cyanide

Cyanide has been commonly used to killfoxes for the fur trade in Australia. The rapid

action of cyanide ensur es that the car cassis found close to the bait point for easyretrieval of the pelt (Lugton 1987). Themanufacture and use of cyanide baits incapsule for m is simple, inexpensive(Appendix B) and poses few hazards ifroutine safety pr ecautions are followed.However, as only 1080 and strychnineare registered for fox control inAustralia, the use of cyanide baits isillegal and should only be used as aresearch or management tool bygovernment agencies.

Cyanide capsules ar e currently beingevaluated in several studies. A number ofdifferent lures and capsule types have been

State/ Registered Recommended Bait applicationterritory poison(s) bait(s) restrictions+

WA • 1080 • Meat (110 g) • Distance restrictions*• Strychnine • Manufactured baits (except hobby farms

subject to APB approval)

NT • 1080 • Meat • None• Manufactured baits

SA • 1080 • Meat, fish, fowl heads, • Property size restrictions liver, eggs • Distance restrictions*• Manufactured baits • Baits must be buried

QLD • Strychnine • Meat • Distance restrictions*• 1080

NSW • 1080 • Meat (100 g) • Distance restrictions*• Fowl heads • Baits must be buried• Manufactured baits

ACT • 1080 as for NSW as for NSW

VIC • 1080 • Cooked meat • Distance restrictions* (25–500 g) • Baits must be buried• Manufactured baits

Note: Foxes are listed as vermin under the Vermin Destruction Act in Tasmania and so can be destroyed, but no poisons are

registered for this use.

+ All states and territories require erection of warning signs in areas where 1080 is used.

* In some states there are restrictions on the distance baits may be placed with respect to human habitation, water supply, and

property boundaries.

Table 7: State and territory legislative r equirements for fox poisoning.

tested. Tuna and aniseed oils have been incor -porated into the wax capsule and a variety ofblended meat types have been used asattractants to cover the capsule. The bestresults have been achieved when using anaturally white capsule coated with a mixtur eof condensed milk and icing sugar , and a r edcapsule covered with a lur e of blood andraw liver blended together into a paste. Redcapsules are made by mixing into the moltenwax a commercial red dye used for impartingcolour into candles.

Results have shown foxes displaypreferences for either capsule type andtherefore a choice is r outinely offered at eachbait station. Bait stations ar e activated at duskand inspected at dawn. Recent tests designedto assess fox pr eferences for other baitmaterials such as fish and cooked liver , haverevealed that fish is less palatable. Cookedliver was as ef fective as raw liver .

Foxes are guided to the stations by a scenttrail created by dragging a car cass from avehicle along the track. An incision is madein the abdomen to allow body fluids to trickleout slowly. Tests have shown that artificiallures, such as meat meal or fish meal, to besignificantly less ef fective than carcasses.

In Victoria, surface baiting is discouragedand not permitted for routine fox contr ol onthe basis of non-tar get risk. The aboveprocedures, developed in Western Australia,are being modified to suit this r equirement(C. Marks, DCNR, V ictoria, pers. comm. 1994).Two types of sodium cyanide ar e underevaluation: a cyanide gel and a powder edsodium cyanide. Both preparations are placedinto specially prepared ‘brittilised’ capsuleswhich are made to withstand transport andhandling and to impr ove the safety aspectsof using the poison. These capsules r equiremore pressure before fracturing than thesofter wax ones. However, once the pr essurethreshold has been exceeded they will‘explosively’ shatter.

Other poisons

The only widely r ecommended poison forfox control is 1080. Although strychnine is

still registered in some states, its use is beingphased out. Cyanide, because of its toxicityand volatility, is only available for scientificpurposes. Potential alter native poisonsinclude anticoagulants such as br odifacoum,bromadiolone and war farin. Before thesecould be r egistered for use against foxes,extensive evaluations of toxicity,humaneness, non-target ef fects and baitdelivery systems would be r equired. At thisstage the expense associated with theevaluations of anticoagulants for fox contr ol(and other alter natives) is not justified.

‘The only widely recommendedpoison for fox control is

1080.’

Alternative poisoning techniques

One of the pr oblems associated withfumigation of fox br eeding dens is the factthat the adult animals ar e often absent fr omthe den when the fumigant is applied. Onetechnique that may possibly over come thispr oblem is the ‘ tarbaby’ poisoningtechnique, developed for rabbit contr ol inthe late 1960s (Hale and Myers 1970). Thistechnique utilises the gr ooming habit ofrabbits by pr esenting the toxic agent in asticky grease on the floor of the warr enentrance. Experiments have tested mixtur esof lanolin and gr ease containing 1.5–2.5%1080 by weight which wer e extruded in afive-track strip. High levels of rabbit contr olwere achieved in early experiments, butthe method was not adopted for r outineuse for a number of r easons. The stickingagent contains a very high concentrationof 1080 and this was seen to pose asubstantial risk to other wildlife speciesand to people. Also r einvasion of treatedwarrens was rapid.

Applied to the entrances of fox br eedingdens, the tarbaby technique is likely to killboth adult foxes and cubs. T iming of theoperation would be critical as the den needsto be tr eated while cubs ar e still being fedby the parents but old enough to emer gefrom the den. The success of the techniquewould depend upon the animals entering


Carcase Dragging

In a study near Boorowa in the Central Tablelands of NSW, NSW Agriculture showed that carcase dragging did not effect the extent to which foxes located and took baits. Not dragging a carcase will effect the costs of fox control by lowering the amount of time required to lay baits.

the den and attempting to r emove the greasefrom their paws by licking. This appr oachto fox management r equires further inves -tigation. Since foxes ar e highly susceptibleto 1080, it may be that the concentration of1080 used can be significantly lower ed.

Bait materials

Meat has many desirable pr operties as a baitmaterial. It is very palatable to foxes and isrelatively target-specific, being attractiveonly to a limited number of car nivores andomnivores. Target-specificity can be furtherenhanced by the manipulation of size andby drying. By making the bait lar ge, andthus lowering the overall concentration of1080 within it, smaller non-tar get speciesare unable to consume enough bait toreceive a lethal dose of 1080. Upon drying,meat initially for ms a crust, and after furtherdrying it takes on a biltong consistency. T estshave shown that smaller car nivorousmarsupials and scavenging birds such asravens, cannot consume it as it is too toughand stringy (Calver et al. 1989). However ,the assumption that dried baits maintaintheir consistency in the field, and hence theirtarget-specificity, has not been demonstratedin the higher rainfall ar eas of south-easternAustralia.

Surface application of manufactur ed orfresh meat baits, which ar e equally or mor eattractive than dried meat baits, may put non-targets at risk because they can be r eadilyingested. Dried meat is the pr eferred baitmaterial in Western Australia especially foraerial application. In other r egions of Australiawhere native fauna have little tolerance to1080, it is important that bait consumption bynon-target species is minimised. Wher e man-ufactured or fresh meat baits ar e used in con-servation areas they should be buried, alr eadya mandatory requirement in many states.

‘Meat is a good medium for1080 poison as it is highly

palatable to foxes andrelatively target-specific.’

The Agriculture Protection Board ofWestern Australia procedure for preparingdried meat baits is as follows:

• meat is cut into 120 gram chunks;

• the centre of each chunk is injected with2.5–4.5 milligrams of 1080 dissolved in 0.15millilitres of water; and

• baits are dried to a weight of 40–50 grams,equivalent to about a 60% loss in weight.Baits may be used within a few days orstored frozen.


7

1080 may be injected into fresh meat baits which are highly palatableto foxes and relatively target-specific. Source: R. Knox, APB

Volume production can be achieved byforced air drying on racks over four days at32°C. However this temperatur e is underreview; a higher temperatur e, 40–45°C,would be more satisfactory as it would inhibitmicrobial growth.

Where meat bait is to be used on agricul-tural land, drying befor e application is notalways necessary. Once baits ar e prepared bycutting into the desir ed size they should beleft to drain on a wir e mesh. This r emovesexcess fluid which might otherwise leach outthe 1080. Baits ar e injected with 1080 solutionusing an accurately calibrated vaccination gun.

Manufactured baits

With an increasing demand for fox baitingprograms on agricultural land, the need fora more readily available and economic foxbait was identified. This led to thedevelopment of a manufactur ed bait (Foxof f)consisting of a soft meat-like substitute basedon meat meal and containing animal fat,preservatives, binding agents and someproprietary flavour enhancers. Ther e are anumber of advantages associated with theuse of a manufactur ed bait. These include:a prolonged shelf-life, ease of distribution,packaging incorporating education materialwhich encourages responsible use, andfactory quality control which allows for theaccurate incorporation of 1080. Wher enecessary a manufactured bait could alsoinclude fox attractants, a vaccine for diseasecontrol and encapsulated 1080 which wouldpotentially reduce non-target uptake. Foxof fbaits are now used extensively thr oughoutsouth-eastern Australia wher e they are fullyregistered by the National RegistrationAuthority. Their use is also supported byappropriate state gover nment agencies someof which issue instructions specific to Foxof fbaiting procedures for fox contr ol. Anexample is presented in Appendix C issuedby the Land Pr otection Branch of theQueensland Department of Lands

A disadvantage of manufactur ed bait isthe loss of r egulation over the use of 1080 asa result of prolonged shelf-life compar ed to

fresh meat baits which cannot be kept forlater use.

Bait concealment: buried baits

As discussed above it may be desirable ornecessary to bury baits to r educe the chanceof non-target animals taking the bait (Allenet al. 1989). This incr eases the labour costs,but these extra costs can be of fset to someextent by using fewer baits and ensuringgreater target-specificity.

Baits should be cover ed lightly with litteror soil to a depth of 5–10 cm to ensur e thatthe bait is not visible. It has been claimedby some that buried baits ar e more attractiveto foxes than sur face baits (Kor n andLugton 1990), although trials have not beenconducted with foxes to confir m this. Forwild dogs, Allen et al. (1989) found thatburied baits wer e equally attractive andpalatable compared to sur face-laid baits.

How long a bait, buried or otherwise,retains its toxicity is dif ficult to quantify asthere are many potential variables involved,particularly rainfall. A suite of soil micr obesand others in water have been shown torapidly degrade 1080 (Eason 1992; King etal. 1991). Staples et al. (1995) assesseddegradation of Foxof f baits after two weeksin loam soil which was either kept dry orreceived 56.4 mm of rain. Mean minimumand maximum temperatur es throughout thetwo weeks wer e 8°C and 17 °C respectively.Degradation was faster in wet soil with only21% of the initial 1080 dose r emaining,whereas baits r emained lethal with 75% oftoxin remaining after two weeks in dry soil.

Aerial baiting

Western Australia is the only state that usesaircraft to lay baits for fox contr ol. Thismethod is illegal in New South W ales andVictoria. An eight-seater plane such as aBritten Norman Islander capable of carryingup to 6000 baits has per formed well inWestern Australia, although smaller air craftcould be used. A chute in the floor fordispensing baits assists bait laying. A spotter


with a sound knowledge of the ar ea to bebaited is r equired to keep the pilot oncourse and to advise the bait dispenserwhen to start and stop baiting. Pr eferredflying height is appr oximately 200 metr es.The aircraft follows transect lines, onekilometre apart, acr oss the site to be baited.The air -speed is dependent on windconditions and drift. Baits ar e dropped atprescribed intervals depending on thebaiting intensity r equired. Prior to the flight,the number of transects and the baitingintensity is calculated in baits per squar ekilometre. The transect length is thendivided by the air -speed to give an evendistribution of baits for the ar ea.

‘Aerial baiting of foxes iseffective for covering large

areas provided the risk of non-target bait take is minimal.’

Aerial baiting of foxes is an ef fective wayof reducing fox populations wher e the riskof non-target bait take is minimal. T o test itseffectiveness, 11 r esident foxes within a studyarea were radio-tagged immediately prior toa baiting program. Baits were dropped at anintensity of six baits per squar e kilometre asdescribed above. Four days after baiting, eightradio-tagged foxes wer e confirmed dead andtwo more by 14 days. Assuming that theuntagged fox population suf fered the samemortality rate, then baiting at an intensity ofsix baits per squar e kilometre killed 91% ofthe foxes. Further pair ed trials at rates of 5and 10 baits per squar e kilometre revealedbait uptakes typically gr eater than 80%; uptakeat 5 baits per squar e kilometre was as gr eatas for 10 baits per squar e kilometre (D. Algar,CALM, WA and P. Thomson, APB, WA,unpub.).

Frequency and intensity of baiting

A pr escription for laying baits for thepurpose of fox contr ol will depend on thesize of the ar ea to be pr otected. Small ar easof approximately 10 000 hectar es or lessrequire frequent baitings because they ar erapidly recolonised by foxes. However ,more information is r equired on fox territory

size, dispersal behaviour and rates ofrecolonisation to better quantify the size ofareas which can be pr otected and hencethe area over which baiting would need tobe conducted.

In Western Australia, small ar ea baiting hasbeen restricted mainly to natur e reservessurrounded by far mland. These have beenroutinely baited once per month. Baits ar elaid from a moving vehicle travelling alongthe perimeter firebreaks by tossing baits undershrubbery at intervals of 100–200 metr es. Anyinternal tracks ar e baited as well.

This baiting r egime has been used forten years at dif ferent sites. In each case,low density populations of marsupials haveincreased markedly, but it is expensive.Studies ar e required to deter mine theminimum intensity of baiting r equired toprotect native wildlife at risk fr om foxpredation. Kinnear et al. (1988) found thatfoxes rapidly invaded 160–300 hectar ereserves following removal of resident foxes.It was on this infor mation that a monthlybaiting regime was adopted.

‘Small management areasrequire frequent baitingsbecause they are rapidly

recolonised by foxes.’

In a r ecent baiting pr ogram, baitingfrequency was r educed to three monthintervals (four baitings per year) and baits laidevery 200 metres. Bettongs were released intothe area in 1980 without fox contr ol but failedto thrive. Trapping capture rates wer e nearzero before baiting and again two years later .In 1993 the trapping success had incr easedto 5%. This is still low, but clearly, bettongdensity is increasing. Monitoring will continueto see if the population will incr ease andstabilise at this baiting intensity. By way ofcomparison, a pr evious study showed thatbettong capture rates reached as high as 30%after five years of baiting at monthly intervals.

Another factor that wildlife managers needto consider is the desir ed level of incr ease inthe target wildlife species. For example, is itintended to have the pr ey to increase to thecarrying capacity of the habitat, or is some


7

arbitrary percentage of the carrying capacitymore desirable?

Factors such as available r esources forsustained control, fox density, the rar enessof the prey, amount of cover , prey vulnera-bility and area of habitat will deter mine thelevel of ef fort required to control foxes.

Baiting procedure: agricultural land

The most common fox poisoning strategyinvolves laying baits at r egular intervals alonga trail. Dragged carcasses, offal enclosed in abag or any matter that leaves a scent trail, canbe used to attract foxes fr om a distance. Scenttrails can significantly increase the initial rateof uptake which is an advantage wher e timeis limited. However, recent evidence indicatesthat foxes will find most baits r egardless ofscent trails. In many cases the use of scent trailscan encourage individual foxes to find andremove many more baits than is necessary,particularly during the period after 1080 is firstingested and before it starts to take ef fect.Where scent trails are used, they should at leastbe interrupted at regular intervals to minimisethe occurrence of multiple takes.

The trail should be accessible by vehicleand preferably follow known featur es suchas fence lines, pr operty roads, tracks or stock

trails, and animal pads so that baits can beeasily relocated. Foxes tend to follow thesefeatures when moving about their homeranges. Trails should be selected during theplanning procedure.

‘Baits are best buried inshallow depressions to reduce

non-target risk and extendbait freshness.’

Baits are best buried at r egular intervals(100–500 metres), in shallow depr essionswhich reduces non-target risk and extendsbait freshness. In some states this pr ocedureis mandatory. As a general guide use 50 baitsper 400 hectar es. The baiting pr ogram shouldlast about 2–3 weeks with baits inspectedevery 2–4 days and r eplaced if taken. It iscommon for lar ge numbers of baits to beremoved at the beginning of a pr ogram, dis-proportionate to the expected number offoxes. This could be r elated to the cachingbehaviour of foxes wher e they store surplusfood without necessarily eating it. Bait shouldbe offered until no mor e is being taken. Ifsurplus baits are cached by foxes and r emainuneaten there is a potential risk to non-tar gets.The issue of multiple bait take and the ultimatefate of all r emoved baits requires furtherresearch.


Manufactured baits have a prolonged shelf-life and ensure accurateand consistent 1080 concentrations. Source: Applied Biotechnologies

Bait Caching

A study on fox predation of lambs near Boorowa in NSW showed that foxes cache introduced Foxoff® baits following the baiting procedures recommended by RLPBs and the manufacturers of Foxoff® where baits were spaced between 400-500m apart. In the nine 1080 trials completed, 170 baits fitted with micro-transmitters were offered of which 53 (30.6%) were taken by foxes with 16 (9.4%) of these found cached. A large number of these caches were within 10-50m of the original bait station, but some were found up to 800m away. Therefore not only can baits be moved between paddocks, but possibly onto neighbouring properties. In the free-feed bait trials the majority of caches were retrieved within the first 3 days after caching, with 66.7% retrieved within 9 days. In the 1080 bait trial only 43.7% of the baits were retrieved within 9 days leaving 56.3% of caches unretrieved after 10 days. It is unknown whether the caches were retrieved by the same fox which made the cache, or another individual. Similarly it is unknown if the same fox or another individual was responsible for moving a cache to another location. Overall, bait caching represents 9.4% (16/170) of the total number of baits placed out during these trials. A number of these were retrieved but 5.2% (9/170) of the total number of baits offered remained cached at the end of the trials. While this proportion is relatively small it does pose a potential threat to non-targets, particularly farm dogs which work paddocks following a baiting program. Users should be made aware that caching does occur and baits can be moved up to 800m or possible further. Perhaps of more significance is the number of baits this represents on a state-wide basis. For example, if one million baits are placed out annually then up to 30.6% (306,000) should be taken by foxes, 9.3% cached (93,000) and 5.2% (52,000) may never be retrieved. Each of these is potentially a non-target threat. There may be potential to reduce the number of baits placed out during a fox poisoning program. The distance between baits might be able to be increased or pulse baiting might be considered. Continued work in this area is required to tighten baiting recommendations and improve the environmental soundness of baiting programs.

Carcase Dragging

In a study near Boorowa in the Central Tablelands of NSW, NSW Agriculture showed that carcase dragging did not effect the extent to which foxes located and took baits. Not dragging a carcase will effect the costs of fox control by lowering the amount of time required to lay baits.

‘The risk to non-target animalsfrom cached baits needs

further investigation.’

Free feeding with unpoisoned bait is notusual, although how much this mightinfluence the success of the poisoningoperation is unknown. Wher e there isspecial concer n about local non-tar getanimals such as bandicoots or quolls, fr eefeeding in conjunction with sand plots canbe used to assess risk befor e poison baitsare of fered. In some cases, wher e lowdensities of foxes exist or individual foxesare being targeted, the use of a car cass as abait station or attraction point has beenemployed. Once foxes have been attractedto the area, poisoned bait can then be placednearby. Caution is needed when using baitstations as they may also attract non-tar gets.

Timing of control: agricultural land

Fox contr ol using poisons is usuallyconducted in the month leading up tolambing or kidding to r educe local foxpopulations and pr edation rates. This canoccur from early autumn thr ough to latespring depending on the r egion. Theeffectiveness of a poisoning operation maybe improved by taking advantage of thepeak demands for food by foxes (Chapter2), although this has not been testedexperimentally. For example, br eedingvixens might be most vulnerable during lategestation and lactation (spring) when theirfood demands ar e sufficiently high toincrease foraging activity, and hence theprobability of locating bait. Dominant malesmay be mor e exposed to bait during themating season (winter) when they ar emoving over much lar ger areas in searchof mating opportunities. Late summerpoisoning for autumn lambing is per hapsat a time when fox populations ar e underleast food pr essure due to an availability ofalternative prey and when it is likely to beleast effective, although sub-adults fr om theprevious breeding season will be foragingfor themselves at this time and ar e morelikely to sample all food types (includingbait). Similarly, any foxes poisoned at this

time will be quickly r eplaced by sub-adultsduring the dispersal period. Conversely, ifpoisoning is not carried out prior to thepeak pr edation t ime, any localisedpopulation reduction may be compensatedby reinvasion. Maximum ef fect on foxes bypoisoning for the purposes of agriculturalprotection may therefore necessitate twocontrol programs per year depending onthe time of lambing. One of these shouldcoincide with the lead-up to peak pr edationwhile the other should take into account thebehaviour of foxes.

7.5.3 Hunting

The hunting of foxes either for their pelts, abounty or mer ely as a sport has long beenseen by the agricultural community as auseful and economic way of r egulating foxnumbers. The commer cial value of fox peltsas determined by export prices saw lar genumbers of animals taken for this purpose.The majority of these wer e shot with theremainder either poisoned or trapped.

Hunting of foxes is time consuming andfew landholders carry out this contr oltechnique. It is mor e common for pr ofessionalor experienced amateur hunters to be giventhe rights to take foxes fr om individualproperties. With the falling value of fox pelts,and in the absence of bounties, this is nowleft to the mor e enthusiastic amateurs and afew remaining professionals.

Shooting

Shooting is usually done at night fr om avehicle and with the aid of spotlights (100W). Small bor e, high-velocity rifles, forexample .222 calibr e, fitted with telescopicsights are preferred. Night spotlight shootingoften relies on the ability of the hunter to lur einquisitive and inexperienced animals intoshooting range by rabbit whistle, or toapproach the animal without it r etreating.Coman (1988) observed that fewer foxescould be taken by this technique as the seasonprogressed due to either rapid r emoval ofyoung or inexperienced animals or lear nedavoidance of shooters.


7

In many districts, r ecreational shooters withhigh-powered rifles are invited onto far msjust prior to or during the lambing seasonand the resultant localised r eduction in foxnumbers may give some temporary r espiteto lamb predation losses. The method is notsuitable where there is dense cover for foxes.

Newsome et al. (1989) r emoved foxes andcats from Yathong Nature Reserve by shootingand observed significant increases in rabbitscompared to control areas with no fox or catshooting. The ef fort was considerable, oneweek in every two or thr ee. It is not known ifthis level of ef fort would have been suf ficientto allow native pr ey species to incr ease or ifthe cost was justified. Replacement of shotfoxes was high, particularly during the periodwhen young foxes wer e dispersing.

Battues or fox drives

Fox drives are still common in some ruralcommunities. Here, groups meet infor mallyand use unarmed beaters, often with dogs,to drive foxes into a waiting line of guns.Usually it is only small ar eas of prime foxcover that are treated. Significant numbers offoxes can be taken but the ar ea of land tr eatedis usually very small with human r esourcerequirements prohibitive. For this r eason, thetechnique provides little long-ter m controlof fox damage. The advantage of this methodis that it is not selective in ter ms of the typeof fox forced to bolt fr om its cover into therange of the hunter, and may help to furtherreduce populations already subject to baitingand spotlight shooting and which containmostly wary adults.

Dogging

Another technique of fox hunting found insome parts of Australia is the use of smallterrier dogs to flush foxes fr om dens.Dislodged animals are either killed withshotguns or coursed with lar ge lurcher dogs.As with fox drives, this technique pr oduceslittle more than a temporary and localisedreduction in fox damage and also cannotbe condoned on animal welfar e grounds(Section 5.3).

Traps

Traps have been used for centuries tocontrol pr edators or for commer cialharvesting, although the captur e of foxesis relatively dif ficult compared to otherspecies. Recently ther e has been muchopposition to their use on animal welfar egrounds (Section 5.3) and considerableeffort has been put into development ofmore humane traps (Novak 1987). The useof steel-jawed traps on agricultural land iseither discouraged or banned in most statesand territories. It is also a labour intensivetechnique which makes it impractical forlarge-scale operations. Steel-jawed trapshave considerable non-tar get catches thatare usually fatal or cause serious injury.

‘Steel-jawed traps are notrecommended and are banned

in some areas.’

In some cir cumstances, fox damage mayoccur in situations wher e conventionalcontrol techniques ar e not practicable. Themost common example is fox contr ol inurban or semi-urban ar eas where use ofpoison baits is seen as an unacceptable riskto domestic cats and dogs. In V ictoria, atreadle snare trap originally developed forwild dog contr ol, has been used for thecapture of foxes in urban ar eas (Coman,unpublished data). This leg-snar e device isa more humane alter native to the steel-jawedtrap and has been accepted as a suitable foxcontrol technique by the RSPCA. However ,such traps ar e dif ficult to set, and it isunlikely that they would be suitable for useby the general public.

‘Steel-jawed traps may kill orinjure non-target animals.’

The treadle snare consists of a thr owerarm, activated by a conventional trap plate,which draws a cable noose about theanimal’s leg. Treadle snares are buried in amanner similar to that of conventional steel-jawed traps and ar e set on runs or used withlures. A small locking bracket is incorpo -rated into the snar e cable such that, oncetightened about the animal’s leg, it cannotbe loosened.


The snare cable usually causes minimalinjury and, importantly, non-tar get speciescan be r eleased relatively unharmed. Thesnare plate is set to withstand a certainweight before triggering which minimisesrisk to most smaller animals. If animals ar eallowed to r emain in these snar es for aprolonged period, severe tissue damage andfractured bones may r esult. Treadle snaresthus need to be checked at r egular intervals,preferably every 4–8 hours, so that captur edanimals can be humanely r emoved anddestroyed.

Queensland legislation allows the captur eof foxes using soft catch traps which wer edeveloped in the USA as a humane springtrap (Section 5.3.5). Unlike the traditionalsteel trap, they have rubber -like paddingon each jaw which cushions the initial impactand provides friction thus pr eventing thecaptured animal from sliding along or outof the jaws. They have several modifica -tions that are designed to r educe the risk ofinjury to a captur ed animal. These ar e: off-set jaws that have a gap of 6–8 mm betweenthe jaws when closed; r educed springstrength; a spring added to the anchor chain;and a centrally attached bottom swivel towhich the chain is attached.

Hunting effectiveness

The proportion of juvenile to adult foxesin a population is a good indicator ofhunting intensity pr oviding the populationcan be sampled with minimal bias towardsany age gr oup. Harris (1977) compar ed afox population with r elatively light contr olmeasures to other studies with dif feringlevels of contr ol. He found the ratio ofjuvenile to adult animals varied fr om 1:1 inlow control areas to as high as 6:1 wher eintensive control was carried out. In asample collected by Coman (1988) inVictoria between 1982–84 this ratio was1.2:1, suggesting only a low level of foxcontrol despite intensive hunting for peltsat the time. While hunting may have someeffect on overall fox densities, it is generallyagreed that r eductions will be minimal. Thishas been observed thr oughout the fox’s

natural range wher e hunting has been usedto reduce predation, to pr event the spreadof rabies, or for commer cial harvesting(Phillips et al. 1972; Hewson and Kolb 1973;Storm et al. 1976; Harris 1977; Macdonald1980; Hewson 1986; Voigt 1987; Wandeler1988).

‘Hunting has minimal effect onfox numbers.’

7.5.4 Den destruction andfumigation

This can be an ef fective technique to r educefox numbers at the time when cubs ar e born(August/September). The vixen only r emainsin the den with cubs for the first few weeksof life and the dog rar ely inhabits the sameden. From the commencement of weaningthe adults will lay up away fr om the cubs,returning at frequent but short intervals withfood. No fumigants ar e specifically registeredfor foxes. However, phosphine and chlor opi-crin which are recommended fumigants forrabbit warrens are commonly used, butphosphine is the pr eferred fumigant in ter msof relative humaneness (Section 5.3.4).

Neither fumigant is humane, althoughother fumigants such as carbon monoxidecould overcome these concer ns (Section5.3.4). Where the den is accessible it can bedestroyed by deep ripping. Den destructionand fumigation can also af fect non-targetspecies. Due to pr essure from humanesocieties and public opinion, den fumigationof foxes for rabies contr ol was abandonedin most Eur opean countries after 1975(Wandeler 1988). The major disadvantageof this strategy is that fox dens, other thanin urban ar eas, are not easily located. Unlessthey have pr eviously been rabbit warr ens,fox dens only have a small number ofentrances which ar e usually discretely hiddenunder tree roots or r ocky outcrops. Wheredens can be located and tr eated, survivingadults (except those in urban ar eas) willrarely reuse them in following years and insome cases may change their behaviour toavoid new den sites being discover ed.


7

7.5.5 Exclusion fencing

A recent r eview of the ef fectiveness ofexclusion fences for foxes (Coman andMcCutchan 1994) found that although mostof these fences pr ovided a barrier to foxes,this barrier was not complete. The key tosuccess is good fence maintenance, fr equentmonitoring of the enclosed ar ea for thepresence of foxes, and quick action toremove any animals which br each thebarrier. Coman and McCutchan concludedthat not enough consideration was given tothe integration of contr ol and exclusionmethods available. When a barrier isbreached by a fox, the damage to enclosedwildlife or domestic stock can be consider -able. Foxes have been known to raise a litterwithin an enclosure, and to r outinely scalea formidable electrified fence to hunt andto return with food for their young.

‘Foxes can scale electrifiedfences.’

There is a lar ge range of fence designs,but generally little detailed infor mation ontheir ef fectiveness. However, the reviewconcluded that exclusion fencing r emainsan important tool in the management ofthreatened or endangered species. Exclusionof foxes by fences is dif ficult due to theagility of the animal and the pr ohibitiveexpense in lar ge areas such as natur ereserves or lambing paddocks. Decisionson whether or not to use pr edator-proofenclosures cannot be taken in isolation fr omthe more general consideration of long-ter mmanagement of the species being pr otected.

‘Little is known about howeffective fences are against

foxes.’

The National Consultative Committee onAnimal Welfare (Department of PrimaryIndustries and Energy 1992) concluded thatexclusion fencing had a limited r ole invertebrate pest management. Simple wir e-netting fences alone ar e rarely effectiveregardless of the height. However wher ezoos, private wildlife parks or intensiveagriculture is subject to fox pr edation,exclusion fencing, pr eferably incorporatinga roof or over hang, has been ef fective. Somesuccess has been achieved using highnetting fences with unstrained over hangingtops, for example W arrawong Sanctuary inSouth Australia. Appar ently the floppynature of the upper fence r esists any attemptby foxes to climb it. Electrified fences mayalso exclude some foxes pr oviding they areproperly designed and maintained. Othershave used fences incorporating acombination of wir e-netting and electrifiedwires, but irr espective of fence type,maintenance costs can be substantial andfrequent monitoring of the enclosed ar eafor the pr esence of foxes is still necessary.Fences can have negative ef fects on non-target species thr ough entanglements,accidents or r estrictions on movement.

Natural water barriers such as r emoteislands are effective barriers to foxes and,


Exclusion fencing for foxes is only viable whenprotecting native species of high conservationvalue. Source: R. Knox, APB

indeed, some mammal species for merlywidespread on the mainland ar e only foundon such islands. It is ther efore essential thatthese island r efuges be kept fox fr ee.

‘Fences can interfere with themovement of non-target

animals.’

7.5.6 Farming practices

Alternative stock management practices mayreduce fox pr edation. Smaller lambingpaddocks close to homesteads make it easierto monitor the flock and r educes the chanceof young lambs being left unattended by themother. Shed lambing of valuable animals canalso be used. Foxes usually only kill lambs upto one week of age. Lambing can be r estrictedto as short a period as practicable so thatsusceptible lambs ar e only available over alimited period. Ideally this should be done incollaboration with neighbouring pr operties.The timing of lambing may also be critical(Section 7.2.3). Fox densities ar e lowest duringearly spring, prior to r eproduction and aftercompletion of dispersal. Selection of flocksfor more protective mothers may deter foxesfrom approaching lambs. Some pr oducershave successfully used trained guard dogs toprotect flocks fr om lamb predation. Thesuccess of Mediterranean stock guard dogbreeds in the goat industry is well documentedby dog and goat br eeders (E. Scheurmann,International Wool Secretariat, pers. comm.1994).

‘Foxes usually only kill lambsup to one week of age.’

The density of fox populations dependson the productivity of the envir onment. Lambsare a minor component of the fox diet. Catling(1988) and Pech et al. (1992) found that thesize of a fox population in summer wasdependent on the availability of rabbits overthe preceding rabbit breeding season. Withthe importance of rabbit in the diet of foxesthroughout Australia (Chapter 2), manipula-tion of this pr ey species may indir ectly reducethe fox population and hence levels of lambpredation. Catling (1987) also suggests thatremoving carrion such as kangar oo carcasses

may have a similar ef fect, or alter natively,providing carrion during lambing may r emovepredation pressure without r educing the foxpopulation. Neither of these strategies havebeen tested.

‘Domestic dogs can be trainedto protect sheep flocks from

foxes.’

Newsome (1987) suggested that integratedfox management was essential if levels ofpredation were to be r educed. Ad hocmanagement is not ef fective. A combinationof adaptive far ming practices (Section 8.3),an effective fox management pr ogram, andreductions to their natural food supply tolimit breeding success is r equired. While thisapproach is logical, the optimumcombination of strategies to obtain economicrelief from lamb predation may be dif ficultto identify.

7.5.7 Fertility control

Reductions to the r eproductive performanceand hence population densities of pr edatorsby oral administration of anti-fertility agentshas been attempted in the past with onlymarginal success (Linhart and Enders 1964;Linhart et al. 1968; Oleyar and McGinnes1974; Allen 1982). Diethylstilbestr ol (DES),a synthetic oestr ogen, has been commonlyused for this purpose. While DES causestemporary sterility, its value is limited byproblems with bait acceptance, therequirement for precise timing of baitingrelative to the animal’s br eeding cycle, andthe carcinogenic properties of the drug(Bomford 1990).

‘Reducing fox fertility is notyet a practical technique for

reducing fox numbers.’

Orally active ster oid hor mones orantihormones that induce abortion havealso been pr oposed as a method for fertilitycontrol (Short 1992). These compoundsshow a degr ee of species specificity due tovariation in the structur e of the uterineprogesterone receptor and could be usefulfor species with short br eeding seasons such


7

as the fox. In pr eliminary baiting trials onwild foxes, an abortifacient was tested at acombination of urban and rural den sites(C. Marks, DCNR, V ictoria, pers. comm.1995). Bait uptake appr oached 90%indicating no aversion to tr eated baits. Theresulting observations of cub activity wasalso markedly reduced at treated dens whencompared to untreated dens.

While a range of techniques andsubstances are now known to r educe thefertility of foxes, r educing fertility will notnecessarily lead to a decline in populationdensity or in damage caused by foxes. Lar ge-scale field experiments would be needed todetermine how practical it is to deliver thesecompounds to wild foxes and to evaluatetheir effectiveness for r educing populationsize. Delivery of fertility contr ol drugs towild foxes is likely to be expensive and theymay be less ef fective for population contr olthan poisons (Bomford 1990; Bomford andO’Brien 1992).

Recent understanding of the molecularbasis of fertilisation makes it possible todevelop new strategies to suppr ess repro-duction in free-living animals. Such r esearchis being undertaken by the CooperativeResearch Centre (CRC) for Biological Contr olof Vertebrate Pest Populations establishedin 1992 and tar geting initially the rabbit andfox (CSIRO 1992). The theory behind theresearch is that the genes for pr oteins thatare critically involved in fertilisation orimplantation of eggs can be inserted into avirus that infects the tar get species. Ananimal infected with the virus would simul -taneously raise antibodies to the virus andreproductive protein, r esulting in theprevention of pr egnancy, but at the sametime not impair the nor mal endocrinefunction and reproductive behaviour oftreated individuals. Among social speciesreproduction by subordinate members ofthe group may be inhibited by dominantmembers (Mykytowycz 1959), while in otherspecies there is active competition amongmales for access to br eeding females. Inboth situations sterilisation of dominantmembers could theoretically reduce the pro-

ductivity of the tar get population (Caughleyet al. 1992).

For the fox, no specific virus has beenfound that will not also af fect dogs. Thecurrent approach of the CRC involves thedirect presentation via a bait of a selectedprotein or a r ecombinant virus (T yndale-Biscoe 1994). The latter has been used verysuccessfully in Eur ope to immunise wildfoxes against rabies (Artois et al. 1987).National concer ns about the eventualoutcome of this work ar e the possibleconsequences to human health, domesticstock, companion animals and native fauna.International concerns are directed at therisk to foxes in countries wher e the speciesis indigenous. Close scrutiny is maintainedon any potential domestic risks, and sincethe work on the fox is curr ently directed atoral delivery of non-disseminating vectors,this poses no risk inter nationally (Tyndale-Biscoe 1994).

An effective form of biological contr olof foxes appeals as a long-ter m and cost-effective method for fox management overlarge areas. Although the risks involved indeveloping a suitable technique ar e high,so are the potential benefits. ANZF ASstrongly supports the development offertility control measures as a mor e humanetechnique for contr olling pest animals suchas foxes. However, while these techniqueshave potentially enor mous benefits, it is notyet possible to assess the likely outcome ofsuch research. If successful it may still bemany years befor e any tangible benefitaccrues. In the meantime, and pr obably asan adjunct to biological contr ol, con-ventional fox contr ol strategies still needto be developed and employed by landmanagers.

7.5.8 Habitat modification

There is some evidence that the wester n ring-tail possum (Pseudocheirus occidentalis) canwithstand fox pr edation if the for est canopyis closed (P. de Tores, CALM, WA, pers.comm. 1993). Protection is needed in openwoodland where possums have to travel


Immunosterility for Fox Control

The following is an abstract on immuno-sterility is from the book Australia’s Pest Animals: New Solutions to Old Problems’ P. Olsen, Kangaroo Press (In Press). Genetically manipulated viruses that cause sterility have some potential for pest control, but research is still at an early stage. The research is exciting in that it uses the novel combination of genetic manipulation and microbiological processes (see box ‘Immunosterility to control foxes, rabbits and house mice’). However, it will be many years before a fully developed agent will be ready for field trials. Firstly, the technological difficulties associated with developing the genetically engineered immunocontraceptive agent must be overcome. Then it must be demonstrated that the agent has the desired effect and only affects the target pests. BOX———————— Immunosterility to control foxes, rabbits and house mice The Cooperative Research Centre for the Biological Control of Vertebrate Pests is attempting to develop genetically engineered viruses to control pests by immunosterilisation (Tyndale-Biscoe 1994). immunosterilisation is a captivating idea. The aim is to use a virus, or some other vector, to carry an agent that stimulates an auto-immune response in the pest animal and renders it sterile. The agent can be a protein from the pest animal’s reproductive system, which is introduced into the virus’ genetic material. When the virus infects the pest animal and multiplies, it also replicates the protein. The immune system identifies the virus, and protein, as foreign and attacks the protein even where it occurs in the animal’s own reproductive system, making the animal sterile. The hope is that reduced fertility of the infected population will result in lower pest density and reduced pest damage. There are several components to this research: • Virology - locating a suitable vector If the sterilising agent is to be spread by a virus, one must be found that is specific to the target animal. For House Mice, the mousepox or Ectromelia virus is being used for initial development of the technique, but it is not specific to mice and will never be used in the field. Mouse megalovirus, already present in the wild mouse population, may prove to be more suitable. The myxoma virus, which only affects rabbits, has been chosen as a possible vector for rabbits. To date a virus specific to foxes has not been found as promising candidates also infect dogs. Thus, for foxes, the possibility of distributing a non-viral antifertility agent through baits, rather than through a self-spreading virus, is being researched. Once a suitable virus has been identified, its genetic sequence must be determined and a site located into which the antifertility protein can be inserted. • Reproductive biology - locating a suitable anti-fertility protein and conducting laboratory trials A search is being made for a protein on sperm or in the female reproductive tract of the pest animal that can be used to stimulate an antibody attack. Several likely candidates have been located and some have been shown to cause an immune response and infertility when injected into the pest animal. Recent laboratory trials with altered Ectromelia virus have dramatically lowered fertility in female mice and are the first indication that virally vectored immunocontraception can work. • Field ecology - investigating the biological effects of sterility and behaviour of the virus in the wild The aim of this component of the research is to test the effects of sterility on pest animal populations. To achieve this, immunosterility is mimicked by tying the fallopian tubes of females. This sterilises the female but does not inhibit normal hormone function and hence, hopefully, normal behaviour. The response of the pest animal population to different levels of sterility is being tested. Preliminary results indicate that 50% or more of the sexually mature females in the rabbit population may need to be sterilised before the population will fall significantly (Twigg et al. 1995). Other aspects of this research include monitoring changes in the behaviour of the sterilised animals and estimating the likely reduction in damage due to any reduced densities of the pest animal. Transmission and survival of the virus in an effective form in the wild will also need to be researched. Twigg, L.E., Martin, G.R., Lowe, T.J., Griffin, S.L. and Gray, G.S. (1995) An experimental evaluation of controlling the fertility of wild rabbits (Orytolagus cuniculus). Proceedings of the 10th Vertebrate Pest Conference, Hobart, 384-391. END BOX——————————

across open gr ound between trees and alsoduring periods of extr eme temperatures whenpossums seek heat r efuges on the gr ound.While this might be an isolated example, itillustrates that habitat modification may havea role in pr otecting wildlife fr om foxpredation. Kinnear et al. (1988) concludedthat fauna subject to fox pr edation can onlysurvive in sites that act as a r efuge frompredators. Removal of pr edators allows preyto utilise less pr otected sites. Conversely, notchanging habitat wher e susceptible speciesare present or recreating necessary habitatmay also pr event fox predation. Loggingactivities and the establishment of r oadsthrough undisturbed habitat for example,may allow foxes to colonise new ar eas whichcontain endangered or vulnerable species(Mansergh and Marks 1993).


7


8. Strategic managementat the local andregional level

Summary

This chapter outlines the process for planningand implementing the strategic managementof fox impact at the local and regional level.The components of a strategic managementprogram are problem definition; developinga management plan; implementing the plan;and monitoring progress.

Defining the problem — With limited (butimportant) evidence the authors concludethat the fox has a significant impact onAustralia’s native wildlife. The difficulty forthe land manager is that the extent of theproblem can only be revealed by long-termevaluations of prey recovery after intensiveand continuing fox management. In mostcircumstances it has to be assumed that wherethe distributions of foxes and susceptible,endangered or vulnerable species overlap, foxpredation occurs. Therefore, fox control mayneed to be initiated before the extent of theproblem can be accurately defined. Theimpacts of foxes on agricultural productionare not well understood. However, becausethe prey — lambs and goat kids — can beintensively monitored, fox impact can moreeasily be defined.

Management plan — The first step inmanagement planning, setting managementobjectives and performance indicators,recognises that the specific conservationobjective for fox management is to promoteincreases in population of endangered faunato viable sizes. For agricultural productionthe objective is to maximise the benefits of foxcontrol compared to the costs. Objectives forparticular situations should include interimand long-term goals, a time-frame forachieving them and indicators for measuringperformance. Because of inherent difficul-ties in determining fox populations, thesuccess or otherwise of fox management mustbe measured by the response in the preyspecies. For conservation values, the best

per formance indicator is a sustainedincrease to viable densities of a threatenedand vulnerable species when foxmanagement measures are implementedand maintained. For agriculturalproduction, lambing (or kidding)percentages are the obvious indicators.Precautionary management is needed toprevent expansion of the fox’s range eithernorthwards or to Tasmania and otherislands.

The second step requires the selection ofthe appropriate management options.Generally, the two options most suitable forfoxes are strategic, sustained management,which is continuing fox control implementedon a regular basis, and strategic, targetedmanagement, which aims to reduce impactat a particular time of the year. With presentknowledge, strategic, sustained managementshould be employed where native wildlife isbeing protected while targeted managementto coincide with lambing is the best optionfor agricultural systems. Having selected amanagement option, the next step is to developan appropriate management strategy. Poisonbaiting with 1080 is the only tested andproven option in both conservation andagriculture. However, factors still need to beconsidered such as methods of application,non-target risks, resources, other pests andsupplementary control techniques.

Implementation — Group action is anessential element of the implementation stage.All those who will benefit from foxmanagement or have a significant stake inthe outcome should be involved in thecoordinated development and implementa-tion of the management plan. This will helpfoster a strong sense of ownership of the plan,and successful management which satisfiesall relevant players is more likely.

Monitoring and evaluation — Operationalmonitoring ensures that the control operationis executed in the most cost-effective manner.It includes the recording of what was done,where and at what cost. Performancemonitoring assesses the effectiveness of themanagement plan in meeting the conserva-tion or agricultural objectives for the program.Both forms of monitoring enable the



8

continuing refinement of the managementplan where necessary.

Economic frameworks are needed to assistin the assessment of the relative value ofalternative fox management strategies. Suchframeworks require: definition of theeconomic problem; data on the relative costsand benefits of fox control; and an under-standing of why the actions of individualland managers may not lead to optimal levelsof fox control and how such problems canbe addressed by land managers andgovernments.

Hypothetical examples of the strategicmanagement of foxes at the local andregional level for conservation and agri-cultural production scenarios are presented.

8.1 Economic frameworks

Economic frameworks need to bedeveloped to assist land managers assessthe relative value of alter native controlstrategies. Such frameworks r equire:definition of the economic pr oblem; dataon the r elative costs and benefits; and anunderstanding of why the actions ofindividual land managers may not lead tooptimal levels of fox contr ol and how suchproblems can be addr essed by landmanagers and gover nments. Land managerscan use such economic frameworks to selectthe most appr opriate fox managementstrategy for their cir cumstances.

Such economic frameworks might beused to deter mine the most cost-ef fectivefox management strategies for theconservation of biological diversity. First,however, it would be necessary to estimatethe economic value the community placeson the conservation of native speciesthreatened by foxes, and also the cost andeffectiveness of fox contr ol techniques forprotecting these species. The pr ocess mightindicate a case for gover nment assistanceif for example the community placed a highvalue on fox contr ol on private far m landto pr otect r emnant populations ofendangered native species, but most

individual landholders did not, and onlyimplemented the lesser levels of fox contr olnecessary to meet their livestock pr oductiongoals. Such gover nment assistance wouldonly be warranted, however , if scientificdata verified that implementing fox contr olon private land would have conservationbenefits for endanger ed native species.Another consideration would be whetheror not assisting private landholders tocontrol foxes was the most cost-ef fectiveoption for meeting these conservation goals,compared to other options, such as investingmore resources in fox contr ol on r eservelands.

Collecting the economic data r equiredto assess the economic costs and benefitsof fox control to pr otect livestock from foxpredation is likely to be easier , althoughthere is still often uncertainty ar oundestimates of fox contributions to lambmortality (Section 7.2.3).

8.2 Strategic approach

The components of the strategic appr oachto fox management have been describedin the Intr oduction. The four steps involvedare defining the pr oblem; developing amanagement plan; implementing the plan;and monitoring and evaluation of theprogram. The challenge for local andregional land managers and others with amajor interest in fox management is to usethe knowledge described in the pr ecedingchapters, and pr ocesses described in thischapter, to develop a strategic managementplan to address the damage caused by foxes.

The pr ocess is illustrated for twohypothetical cases, one for a conservationarea and the second for an agriculturalproduction area.

8.3 Problem definition

Section 7.4 sets out the initial steps indefining the pr oblem of any foxmanagement program, involving themeasurement of fox impact and densitymeasurements using techniques described

in Sections 7.2 and 7.3. Mapping techniquesare very valuable in defining the pr oblem,allocating management units, and estab -lishing priority areas for tr eatment (Section7.4).

Conservation

As discussed in Chapter 3, ther e isconclusive evidence, albeit geographicallyand species limited, that the fox has asignificant impact on Australia’s nativewildlife. Some preliminary indications of foximpact for a particular site might beavailable from direct observations of foxpredation or fr om indirect measures suchas scat analyses. However , the dif ficulty fora land manager is that the extent of theproblem can only be r evealed by long-ter mevaluation of pr ey recovery after intensiveand continuing fox management. W ithpresent knowledge there are no other usefulcorrelates for fox damage. It ther eforebecomes necessary to make certainassumptions about the initial pr oblem.Foremost is wher e the distributions ofthreatened native species and foxes overlap,the assumption must be made thatpredation does occur. This means initiatingmanagement without necessarily accuratelydefining the problem. Once fox contr ol hasbeen initiated, the extent of fox pr edationand other factors which might influence thedesired outcome can be assessed (Section7.2.2).

GIS-based databases such as theEnvironmental Resources InformationNetwork (ERIN), linked to equivalent stateand territory databases, contain infor mationon the habitat, conservation status,threatening processes, and vulnerability ofnative plants and animals. These databasescan help managers deter mine species mostat risk and help plan a coordinatedapproach to protecting those species andareas believed to be most at risk fr om foxpredation. These lists of species most atthreat may be at the r egional, state andterritory and/or national level.

Agriculture

The impact of foxes on agriculturalproduction is not well understood.However, because the pr ey (lambs or kids)can be intensively monitor ed, the impactcan be mor e easily defined and used as abasis to deter mine the extent of fox contr olrequired, or indeed whether any contr ol isnecessary (Section 7.2.3). Car e is neededin assessing impact, because although foxdensities may be monitor ed, the cause oflamb mortalities is less easy to deter mine.

‘An assessment of fox impactshould be based on an accuratedetermination of the cause of

lamb mortality.’

8.4 Management plan

8.4.1 Objectives

The specific conservation objective of foxmanagement is to pr omote and maintainpopulation increases of endanger ed orvulnerable fauna to viable densities. Thiscan be assisted by cr eating more populationsthrough introductions and translocations toareas or sites wher e the species for merlyoccurred. Another objective is to pr eventfuture declines in populations of nativefauna through fox predation.

‘The conservation objective offox management is to promote

viable populations ofendangered fauna.’

For agricultural production the objectiveis clear: wher e fox impact has been identified,the level of pr edation must be r educed to anacceptable level, predetermined by the valueof the enterprise and the cost of contr ol.

8.4.2 Management options

Flexible management

There ar e some new appr oaches tomanaging complex natural systems. One isknown as adaptive management. As


8

described by Walters and Hollings (1990),it is based on the concept that knowledgeof such systems is always incomplete. Notonly is the science incomplete, the systemitself is dynamic and evolving because ofnatural variabil i ty, the impacts ofmanagement and the pr ogressive expansionof human activities. Hence managementoptions must be ones that achieve anincreasing understanding of the system aswell as environmental, social and economicgoals desired. The management of foxes,and other vertebrate pests, using ‘bestpractice’ suggested in these guidelines,embodies many of the concepts of adaptivemanagement, particularly that of ‘lear ningby doing’.

Given the paucity of infor mation,including scientific infor mation, about manyof the factors that drive natural systems,Danckwerts et al. (1992) r ecommend thatmanagers need to adopt the adaptivemanagement approach of ‘lear ning bydoing’. That is, managers lear n from theirown past successes and mistakes (and thoseof their neighbours), and fr om technicalinformation, and make managementdecisions based on experience in situationswhere few facts ar e known, but wher edecisions cannot be postponed.

A key to the flexible managementapproach suggested by Danckwerts et al. isthe monitoring of thr ee key variables in thesystem — livestock pr oductivity (biologicaland economic); vegetation changes; andenvironmental conditions and managementresponses. These issues ar e furthercanvassed in Section 8.5.

Braysher (1993) discusses managementoptions for managing vertebrate pests andthey are summarised below. In selectingan option it is important to match it to thedesired objective and to be r ealistic in ter msof available r esources and technicalfeasibility. A useful aid to this selectionprocess can involve the construction of a‘decision matrix’ to evaluate which optionis most appr opriate and a ‘pay of f matrix’to determine the benefits (Norton 1988).

Local eradication

Local eradication involves the per manentremoval of the entir e population of an ar ea.This option is unr ealistic for foxes except inspecial circumstances such as islands wher ethere is no potential for r ecolonisation, orpossibly on mainland r eserves where long-term perimeter control of foxes is economi-cally and technically feasible. For localeradication to be a viable option, a numberof key conditions must be met (Bomfordand O’Brien, 1995). These ar e set out inAppendixD.

Strategic management

Strategic management of foxes is an optionwhere local eradication is not feasible. Itinvolves integrating fox contr ol operationsinto overall land management planning toachieve a specific fox density or fox impactoutcome. There are three major types ofstrategic management: sustained, tar getedor one-of f.

‘Strategic, sustainedmanagement involves an initial

campaign to reduce foxpopulations to very low levels,

followed by maintenancecontrol to prevent population

recovery.’

Strategic, sustained management involvesan initial widespread and intensive contr olcampaign to reduce fox populations to verylow levels, followed by maintenance contr olto further r educe or at least pr eventpopulation r ecovery. This is the onlypractical option available in most cases formanaging fox pr edation on native fauna. Itis important to r ealise before embarking onthis approach that r esources must beallocated to this action for the for eseeablefuture. Managers need to deter mine thelevel of ef fort at which the benefits ofcontrol at least equates with the costs ofcontrol. However for fox populations cost–benefit relationships are largely unknown.Furthermore, with the most importantimpact being on endanger ed or vulnerablespecies, it is dif ficult if not impossible to

place an economic value on the benefits ofwildlife conservation.

‘The cost–benefit relationshipsof fox control for different

situations are largelyunknown.’

One-off management involves a singleaction to achieve the long-ter m or per manentreduction of fox damage to an acceptablelevel. Examples might include constructionof a permanent fox-proof fence or r elease ofan effective biological control agent. Fencingis likely to be pr ohibitively expensive exceptin small areas protecting high-value species.Development of an ef fective biological controlagent is in its infancy.

‘Fencing is usually only a cost-effective option for protecting

high-value species in smallareas.’

In the case of strategic, tar getedmanagement, control ef fort is targeted tomanage fox damage at a particular time ofthe year. Advantage may be taken ofbiological factors of the fox (for example,when it disperses or when vixens ar e mostfood str essed) or when the pr ey isvulnerable (during lactation and gestationfor example). As with strategic, sustainedmanagement, cost–benefit r elationships forthis option are largely unknown. However,should it be found to be economicallyjustified, strategic, targeted management isthe most appropriate option for agricultur -al protection where control effort cancoincide with lambing (Section 7.5).

Commercial harvesting (hunting)

This form of management aims at pr ovidinga sustained yield of animals which can be con-tinuously harvested without any long-ter mpopulation reductions. With the demise of thefox pelt trade, most harvesting ef fort is nowby recreational hunters. As outlined in Section7.5, hunters have little impact on fox pr edationon lambs and native fauna. The only situationwhere this option may be of use is to assist apoisoning program to target surviving foxes.

‘Recreational fox hunting doeslittle to reduce the impact offoxes on lambs and native

animals.’

Crisis management

In some situations it may be envir onmen-tally or economically justified to undertakeno fox contr ol. This will particularly be thecase in a gr eat deal of agricultural landwhere fox predation is not an issue and con-servation values are judged to be not sig -nificantly threatened. However, if foxes haveintermittent impacts, it may lead to managersundertaking crisis management, killing foxesin an unplanned manner as they appear toaffect resources. This for m of managementis unlikely to pr otect resources.

Precautionary management

It is important to ensur e that the fox doesnot expand its range northwards or on toTasmania or other islands wher e it iscurrently absent and wher e native fauna thatare vulnerable to fox pr edation exist. Thiswill require vigilance in detecting wild foxesin these r egions and public education onthe risks of keeping or r eleasing foxes.

8.4.3 Management strategy

Having determined the most appr opriatemanagement option the next step is tochoose appropriate management techniques(Section 7.5) and to integrate them into amanagement strategy. Variables which mightinfluence this need to be identified andevaluated. These can include:

• the conservation status of the populationof the animals at thr eat;

• the potential for applying strategic contr olto have maximum ef fect on fox populationsat a particular time of the year , for example,through den fumigation at cubbing;

• resources to implement options, forexample, where funds ar e limited buthuman resources are abundant, gr oundbaiting is pr eferable to aerial baiting;


• nature of the habitat (dense canopy, openwoodland or range land) and size andlocation of the management unit haveobvious implications to technique selection,for example, access to management ar eaor rates of bait application;

• potential for non-target losses;

• presence of other pest species such as feralpigs, rabbits or feral cats;

• the potential for r ecolonisation by foxesfrom surrounding land and the ef fect thiswill have on management objectives;

• the bias in some contr ol techniques(shooting for example) towards youngerage gr oups, leaving the br eedingpopulation intact; and

• predator–prey interactions.

‘Animal welfare is an essentialconsideration of any control

program.’

Mapping may be an important step indetermining and r ecording the relationshipbetween variables (Section 7.4.3).Consideration of animal welfar e issuesshould be an integral part of any feral animalmanagement plan, including foxes. ANZF ASconsiders that the curr ent approach to feralanimal management, namely the ad hoc,opportunistic options based on short-ter mreduction in populations ar e inappropriate.They consider that a well planned andcoordinated strategy, as advocated in theseguidelines, is likely to be mor e humane inthe longer ter m.

8.4.4 Performance indicators

Conservation

For conservation values, the bestperformance indicator for fox managementis a sustained incr ease in numbers ofendangered or vulnerable species. Likewise,in the case of translocations, the bestindicator is the successful establishment oftranslocated or intr oduced fauna followedby a sustained incr ease of the population.

An additional per formance indicator, andoften the first positive sign, is an incr easein the use of the available habitat — speciesincrease and occupy ar eas of the habitatotherwise denied them.

‘The best performanceindicator for fox managementin conservation areas is the

sustained viability ofendangered or vulnerable

species.’

The lack of a significant populationincrease of a pr ey species, despiteapparently adequate fox management,would indicate a failur e to achieve theobjective. However it may indicate that otherfactors, in addition to fox pr edation, maybe affecting production and survival of pr ey,for example food supply or quality; mortalitydue to dr ought; disease and parasites; ormortality due to other pr edators such as feralcats, birds of pr ey, reptiles and poachers.For example, in a study of the survival oftranslocated malleefowl chicks to Y athongNature Reserve, food was identified as alimiting factor (Priddel and Wheeler 1990).This study suggests that, given adequateprotection from foxes, the chicks wouldultimately starve. Conversely, givenadequate food and no pr otection from foxes,chicks would be pr eyed upon.

Therefore several factors besides foxpredation may limit pr ey r esponse.Furthermore, failure of prey populations torespond to pr edator control does notexclude fox predation as a limiting factor .Complex factorial experimental designs,where feasible, may be necessary to r esolvemultiple limiting factors and modellingbased on such experimental testing may bevaluable for investigating pr ey populationdynamics under dif ferent fox managementstrategies (Pech et al. 1995). Alter natively,sequential management of likely limitingfactors might be possible. Per formance mayneed to be measur ed over long periodsbefore a positive r esponse is evident. Forexample, with malleefowl per haps onlyoccasional years provide sufficient food forrecruitment.


8

Agriculture

Performance indicators for agriculturalproduction are both straightforward and shortterm. Where fox predation is shown to be alimiting factor, lambing percentages, andhence net income, should immediatelyimprove on previous years’ production witheffective fox control prior to lambing; andshould continue to impr ove where longerterm or sustained management isimplemented. The only wor d of caution her eis that allowances may need to be made forother factors influencing pr oduction beforeand after fox contr ol. These include variationin seasonal conditions. Wher e foxmanagement does not lead to incr easedlambing percentages (criteria for failur e), othercauses of low lambing per centages shouldbe considered, such as poor ram fertility.Rapid recolonisation by foxes may also bereducing the ef fectiveness of fox contr ol.

8.5 Implementation

Implementation of fox management isdescribed in Chapter 9. The value of the gr oupapproach to pest management has beendiscussed in detail in the earlier guidelinesfor rabbits (Williams et al. 1995). The gr oupapproach requires local community support,based on an understanding of the damagefoxes cause and how it can be addr essed. Thegroup approach fosters a str ong sense ofownership of the management plan, andsuccessful management which satisfies allparticipants.

8.6 Monitoring andevaluation

‘Performance monitoring iscritical to ensure managementprograms remain focused onthe cost-effective reduction of

fox damage.’

Operational monitoring and per formancemonitoring (evaluation) are often forgottenbut essential aspects of implementing amanagement program. Both pr ovideinformation which can be used to impr ove

the effectiveness of the contr ol strategy ormodify the objectives as necessary.

8.6.1 Operational monitoring

Operational monitoring aims to assess theefficiency of the contr ol operation, todetermine what was done, wher e and at whatcost. Most states and territories havedeveloped, or ar e developing, PestManagement Information Systems (PMIS)which can assist land managers, whethergovernment or private, to monitormanagement operations both for operationaland performance monitoring (For dham 1991).

8.6.2 Performance monitoring

Performance monitoring aims to assess theeffectiveness of the management plan inmeeting the objectives of the pr ogram.Performance monitoring begins when it issuspected or assumed that foxes ar e causingsignificant environmental or agricultural impact.

The primary management objective is thereduction to an acceptable level of fox damage.Therefore, the index monitor ed to assess theeffectiveness of the fox contr ol program shouldbe the r esponse of the pr ey species targetedfor protection (Section 7.2). This may takeseveral years to achieve, particularly in r elationto population recovery in native species.Performance monitoring allows for the ef fec-tiveness of the pr ogram to be evaluated andmodified where required, or to identify theneed to set new objectives and per formanceindicators.

Achievement of management objectivesshould be qualitatively assessed based onperformance indicators. Dispersal may soonnegate the benefits of localised fox contr ol thusnecessitating expansion of the managementarea. In the case of lamb pr edation, the costof fox contr ol needs to be economicallyjustified in ter ms of increased lambing rates.Evaluation techniques need to take all of thesefactors into account.

Where practicable, knowledge of the dis-tribution and relative abundance of foxes


helps to plan the management pr ogram(Section 8.4). However, estimation of theseparameters is very dif ficult and a land managermay have to r ely on crude estimates orassumptions based on experiences elsewher e.

In conservation ar eas, performanceassessment of the management pr ogramdepends on comparisons of census estimatesof the pr ey species carried out befor e andfollowing the implementation of pr edatorcontrol. In general, if the fox is the primarylimiting factor, as appears to be the case forsome Western Australian marsupials, themethods need not be sophisticated or sensitivebecause census estimates or indices, befor eand after a suitable period of fox contr ol, aremarkedly different.

Irrespective of how management isevaluated, for example r eductions in foxpopulation, increases in distribution andabundance of native pr ey species or incr easedlambing rates, monitoring pr ograms should:

• consider the use of equivalent non-tr eatmentareas to compar e the ef fectiveness of themanagement program;

• consider changes in the parameter beingassessed over time, that is, immediatelybefore and after contr ol and then annuallyor more frequently if r equired;

• use measurement indices and r ecordingprocedures that ar e standardised to enablecomparisons over time and betweendifferent habitat types;

• use methods that ar e compatible with theresources and skills available to the landmanager; and

• include as many between-site comparisonsas resources allow.

8.7 Hypothetical example ofstrategic management atlocal and regional level— conservation

8.7.1 Scenario

This hypothetical case study is set in a 3000hectare national park such as might be found

within the Grampian Ranges of V ictoria.Throughout the park, containing mostly drysclerophyll forest, are a number of graniteoutcrops which ar e known to harbour thethreatened brush-tailed rock-wallaby (Petrogalepenicillata). Other important native speciesincluding the souther n brown bandicoot(Isodon obesulus) and spotted-tailed quoll(Dasyurus maculatus) also occur. Foxes andferal cats are commonly sighted while rabbitspredominate in more open areas. The park issurrounded by agricultural land consisting ofgrazing, crops and open woodland most ofwhich tends to be rabbit-pr one.

Information collected as part of thepreparation of a management plan for the parksuggested that rock-wallaby populations weresignificantly smaller than might be expectedfrom historical records. The pr evious wide-ranging distribution of the species signifiedthat it might be an adaptable generalist, apartfrom its preference for rocky terrain, yet itsnumbers had declined drastically thr oughoutits range with many r ecent populationextinctions. Studies of similar species indicatethat fox predation is likely to be a major factorin population decline.

8.7.2 Defining the problem

In response to these observations, the Parksand Wildlife Service launched a pr eliminaryinvestigation of all r ock-wallaby populationswithin the park. These censuses pr ovidedthe following information:

• the populations were small and declining;three sites supported less than tenindividuals;

• the populations were confined to ar easwhere the rocks were fragmented for mingbreak-aways which provided protectivecover from environmental and predationstresses while lar ger areas of suitablehabitat were not being used;

• Brush-tailed rock-wallaby hair was foundin two fox scats taken fr om the area;

• periodic assessments revealed that therewas no population gr owth even though


8

most females wer e carrying pouchedyoung. Recruitment was low and the agestructure consisted of pr edominantlymature animals;

• there was little or no evidence that thewallabies were subject to sever e physi-ological stresses. Weight losses wer eminimal and body condition was goodeven during a dr ought-declared year; and

• there was no evidence of disease.

The preliminary survey indicated that theconditions seemed favourable forpopulation growth, yet there was none.Observed was a population of fit andhealthy animals unaffected by physiologicalstresses or shortages, pr oducing young andtherefore possessing potential for gr owth,but population growth was essentially static.Clearly there was an unknown sour ce ofmortality preventing population gr owth. Byinference it was concluded that foxes wer ethe greatest threat to rock-wallaby conser-vation. Other limiting factors may haveexisted such as the lack of an essentialhabitat requirement. However these couldnot be r evealed unless the thr eat ofpredation was first r emoved. It was ther eforedecided that a fox management pr ogramshould be implemented within the park.The implications of this decision also neededto be considered in association with foxpredation on rabbits and the potential ofreinvasion by foxes fr om surrounding agri-cultural land.

Removal of foxes could r esult in anincrease in rabbit densities within the parkwhich could in tur n encourage gr eaterinward dispersal of foxes to r eplace thoseremoved. Similarly, the contr ol of foxes inareas surrounding the park in or der toestablish a low fox density buf fer zone couldsee an incr ease in the alr eady significantagricultural impact by rabbits. The pr oblemwas therefore defined as being not only oneof fox management within the park, butalso one of needing to involve adjacent landmanagers in parallel rabbit and fox contr olactivities, especially in the buf fer zone of20 kilometres around the park boundary.

8.7.3 Management plan

Management objective

The extent to which fox pr edation affectedrock-wallaby densities, although not known,was considered to be significant. Pr ovidingthey were able to utilise additional habitatsin the absence of fox pr edation, it was decidedthat a r ealistic objective was to incr ease rock-wallaby density within the park by 400% overthe ensuing four years. The primaryperformance indicator would be an incr easein the rock-wallaby population derived fr omcontinued rock-wallaby census. The need tohave all adjacent land managers participate ina parallel rabbit and fox management pr ogramwas identified as a supplementary objective.

Management options

Strategic, sustained fox management (Section8.4.2) was considered to be the most feasibleoption within the park if r ock-wallabies wereto re-establish. Local eradication, while thepreferred option, was not r ealistic in theabsence of exclusion fencing ar ound theperimeter of the park. W ith limited resourcesin surrounding agricultural land, strategic foxand rabbit management in this ar ea was theappropriate choice. Similarly, strategic rabbitmanagement would be carried out within thepark.

Management strategy

Sustained 1080 baiting pr ograms have provento be the most ef fective means of r emovingthe impact of fox pr edation in conservationareas (Kinnear et al. 1988). The techniquesused to prepare and deliver baits for thispurpose can depend on local legislativerequirements (Section 6.2). In V ictoria, forexample, baits must be buried to a depth ofat least 8–10 cm. This r equirement is partlyto protect non-target species such as the tigerquoll which is susceptible to 1080 baits laidindiscriminately. Similarly, wher e agriculturalland is involved, far m dogs need to beprotected. Baits can be pr ovided as eitherdried meat or pur chased as a manufactur edproduct. Sustained management of foxes


requires regular and continuing poisoningof foxes for the for eseeable future. To whatextent this can be maintained depends onavailable resources.

‘Sustained 1080 baiting is themost effective strategy for

reducing fox impact inconservation areas.’

In this example, it was decided that baitingfrequency should not be less than at thr ee-monthly intervals. This could be supplementedby den fumigation during the br eeding seasonor by spotlight shooting if time per mitted. Foxmanagement on surrounding agricultural landwould usually require management ef fort tobe targeted to protect production (for example,lambs) at the appr opriate time of the year .Therefore, it was essential to encourage neigh-bouring graziers to participate in the pr ogram.From the perspective of pr otecting the parkfrom reinvasion by foxes, contr ol during thepeak fox dispersal period (autumn) wouldhave the gr eatest benefit.

‘Rabbit control should beincorporated into fox

management programs.’

Due to the r eliance of foxes on rabbits, itwas decided that the fox management planneeded to incorporate a rabbit managementstrategy. Strategies suitable for rabbit contr olwill be similar for both agricultural and con-servation areas. For areas of low conservationvalue, these include r emoval of sur faceharbour, destroying warrens by ripping,followed by r e-ripping or fumigation. Theuse of 1080 poison to contr ol rabbits wasnot considered to be an option because ofpotential non-target effects, particularlysecondary poisoning of tiger quolls fr omeating 1080-poisoned rabbits within the park.

8.7.4 Implementation

The nature of this pr ogram requires that thepark management work cooperatively withneighbouring landholders. The advantagesare twofold: the pr otection of conservationvalues and the r eduction of agriculturalimpact.

‘Park management shouldwork cooperatively with

neighbouring landholders toprotect conservation values

and reduce agriculturalimpacts.’

The entire park is the unit for foxmanagement. Mapping of tracks and trailswithin the park will serve as a useful guideto bait placement and also assist in therelocation of baits on a r egular basis so thatthose removed can be r eplaced. The sameapplies to neighbouring agricultural land.Because the latter involves only strategicbait ing, mapping and selection ofmanagement units is per haps mor eimportant. Previously selected rabbitmanagement units should be tr eated in orderof priority. Recolonisation can be minimisedby treating adjacent management units insequence (Williams et al.1995).

8.7.5 Monitoring and evaluation

‘Ineffective baiting programsmay be a result of incorrect

baiting techniques, bait-shyness or fox immigration.’

The overall ef fectiveness of the pr ogramwill be deter mined by the continuing r ock-wallaby census, the desir ed outcome ofwhich is a significant population incr ease.A factor which might contribute to this is anincrease in habitat use by the r ock-wallabies.This should be monitor ed as a per formanceindicator. Failure to ef fectively control foxescould lead to false assumptions being drawnabout the ef fect of pr edation. It wouldtherefore be essential to monitor fox densitywithin the park (Section 7.3). Possiblecauses of failur e might include incorr ectbaiting technique or bait-shyness by foxesand immigration fr om buffer zone. If theseproblems ar e identified, managementtechniques will need to be modified. As auseful encouragement to continuinglandholder participation, the impact of foxpredation on agricultural pr oduction shouldalso be monitor ed (see next case study foran example).


8

The essential message that has emer gedfrom similar but r eal examples for conser -vation agencies and wildlife managers inparticular, is that an exotic pr edator suchas the fox is a major factor in the extinctionprocess of many small and medium-sizedmammals. Predation keeps populationdensities precariously low, thus incr easingthe risk of extinction fr om other causes. Thefact that a species still persists in an ar ea inthe presence of foxes is no guarantee thatthe species will continue to survive. Aproperly implemented pr edator removalprogram can also r eveal the pr esence ofother l imiting factors af fecting theabundance of native species.

In Western Australia, predator removalby baiting has r esulted in large increases innative prey populations. In these instances,it may be concluded that pr edation is theprincipal (proximate) factor r esponsible forlimiting population size, and that the pr eyis existing at levels far below the carryingcapacity of the habitat. W ith predationmortali ty minimised, these W esternAustralian populations have incr easedwithout restraint over a considerable period.Eventually growth will slow and cease whenthe carrying capacity of the habitat has beenreached or as other limiting factors comeinto play.

Undoubtedly, not every pr edator removalprogram will mirr or the Western Australianresponse where appreciable increases inprey numbers have been the rule. Giventhat predator control has been adequate,there are two possible causes for a lessspectacular response. It may be due eitherto the fact that the species is not vulnerableto predators, or the carrying capacity of thehabitat is low due to other limiting factor(s).Priddel and Wheeler (1990) have demon -strated this in the case of malleefowl (Section3.1.2).

Clearly, in situations wher e anotherfactor(s) is limiting the population gr owthof a thr eatened species, studies will berequired to identify the limiting factor(s).This may or may not be a simple task butwhatever the outcome, the initial contr ol of

predators is essential. T o take an example,suppose that food was limiting the densityof an endanger ed mammal that was alsovulnerable to fox pr edation. If it is assumedthat food supplements wer e provided therewould be a number of possible outcomes.In the absence of pr edator control one mayobserve that individuals ar e in a betternutritional state, but with no populationincrease. Subsequent removal of pr edatorsand the addition of food would r esult in apopulation increase. Conversely, predatorcontrol alone would not r esult in apopulation increase as food would also belimiting. Another example might be thatreduced fox numbers allows an incr ease inrabbit numbers. This could r esult inincreased competition for food, andsuppressed population incr ease of athreatened mammal. These examplesillustrate how pr edation can confoundecological experiments (and our under -standing of the factors af fecting wildlife),and conversely, how other limiting factorscan obscure the potential or actual impactof predators.

8.8 Hypothetical example ofstrategic management atlocal and regional level— agriculture

8.8.1 Scenario

This hypothetical case study is based on asheep grazing property of about 20 000hectares in semi-arid wester n New SouthWales. Paddocks consist of open woodland,chenopod scrubland and pastur es of annualforbs and grasses. Sheep-carrying capacityis 20 per squar e kilometr e with theproduction of lambs and subsequent saleof surplus stock making up 40% of thelandholder’s income. Foxes ar e common asare kangaroos, feral pigs, feral cats andrabbits. No endanger ed or vulnerablewildlife species ar e known to occur in thedistrict. A series of good seasons pr oducedlamb marking percentages of approximately50% on this pr operty which fell below thedistrict average of appr oximately 70%.


8.8.2 Defining the problem

In an ef fort to identify the possible cause ofreduced lamb production, the landholdercompared his operation with neighbouringand more successful properties. Aspectsassessed included stocking rate, pastur econdition and timing of lambing, all of whichcan af fect a flock’s nutritional status andhence reproductive performance, as well asram fertility, and blood lines. In all of thesecomparisons he could find no dif ferenceswhich might be causing his pr oblem. In theprevious season the landholder alsocompared wet and dry statistics for one ofhis larger lambing paddocks with a similarpaddock on a neighbouring pr operty. Inboth cases ar ound 90% of ewes wer ediagnosed as pr egnant; however at lambmarking the dif ferences were substantial.From this comparison the landholderconcluded that lamb loss rather than flockfertility was the primary cause for the lowernumber. Few lamb car casses could be foundsuggesting that scavenging of dead lambsor predation of live ones was the cause andnot lack of cover in the lambing paddocks.For those car casses which could be found,predation was identified as the pr obablecause (Section 7.2.3).

The landholder also observed that a smalllambing paddock adjacent to his living ar eaalways produced more lambs per ewe thanthe remainder of the pr operty. This paddockhad a constant exposur e to farm dogs andhumans, and because of attacks on hisdomestic poultry, foxes in the immediatearea were shot on sight. Local shooters hadalso observed lar ger than normal numbersof foxes on the pr operty, particularly inassociation with sandhills carrying highrabbit densities. W ith a combination ofcircumstantial and r eal evidence, thelandholder discounted feral pigs as a majorfactor and concluded that fox pr edation onhis property was r esulting in a significantimpact on lamb pr oduction. Having definedthe problem he decided to implement a foxmanagement program.

8.8.3 Management plan

Management objective

The available evidence suggested that foxpredation may have been causing up to a20% loss in lamb pr oduction. Themanagement objective therefore became thereduction of fox impact thr ough effectivemanagement using lamb markingpercentages as per formance indicators.Because the landholder was unsur e of thecosts involved in fox contr ol a first yearobjective of a 10% incr ease fr om theprevious three-year mean in lamb markingpercentages with ef fective but low-level foxcontrol was set. In the second and thir dyear the objective would be raised to a 20%increase with the level of fox contr oladjusted according to the first year r esults.

Management options

The only feasible management options wer eeither strategic, sustained or strategic,targeted management (Section 8.4). No foxcontrol or crisis management might alsohave been consider ed. However, becausethe landholder lacked infor mation on thecost–benefits of fox contr ol it was decided,as a guide, that some for m of foxmanagement should be undertaken in orderto compare possible increases in net incomefrom higher lamb pr oduction. With no priorexperience in fox management it wasdecided that strategic, tar geted managementwas a more appropriate choice than themore resource demanding strategic,sustained management.

Management strategy

The local Rural Lands Pr otection Boardadvised the landholder that poisoning with1080 was the most cost-ef fective fox contr oltechnique for semi-arid ar eas. Because ofthe difficulty in obtaining fr eshly preparedbaits from the Boar d of fice which was200kilometres away, the landholderpurchased manufactured baits at a cost of$1 per bait.


8

A targeted baiting program was aimed atprotecting lambs at birth. This meant startingfox poisoning operations a week befor elambing commenced and continuing themthrough at weekly intervals until no furtherbait was taken. The r ecommended procedurefor baiting (Korn and Lugton 1990) was tobury baits at 100–500 metr e intervals along adragged scent trail. Bait application rate inthe vicinity of lambing paddocks was 50 baitsper 400 hectares.

The landholder was awar e that foxes r elyon rabbits as a year -round food source. Hehad also observed dead foxes after a pr eviousrabbit poisoning pr ogram. As a r esult, asupplementary objective was undertaken thatroutine rabbit control using 1080 poisoningfollowed by ripping of warr ens would beconducted throughout the year commencingafter the next lambing. He also decided tomodify his farming practices by shorteningthe lambing period as much as possible.

8.8.4 Implementation

Where practicable, fox management for thereduction of agricultural impact should beundertaken cooperatively with adjacentlandholders. Apart fr om obvious cost-effectiveness through benefits from bulkpurchases and sharing equipment, thisfurther reduces the immediate pr oblem ofrecolonisation particularly when strategicbaiting aims to pr otect lambs.

The selection of management units on aproperty will depend partly on availableresources. One landholder attempting toprotect all lambing paddocks equally wouldnecessarily treat the entir e property as amanagement unit. Where some lambingpaddocks are more susceptible to pr edationthan others, smaller management unitswould be necessary with priority given tothose at greatest risk.

Because it is dif ficult to pr edict the dis-tribution of foxes, mapping is important toidentify the location of lambing paddocks,areas of high rabbit density wher e foxesmight be concentrated, and featur es such

as fence l ines, tracks and pr opertyboundaries where bait trails will need tobe laid. Mapping will also be an aid tomonitoring bait uptake.

8.8.5 Monitoring and evaluation

With virtually no infor mation on thecost–benefits of fox contr ol for agriculturalprotection, the landholder should place ahigh priority on monitoring and evaluation.Fox management is too often implementedwithout hard evidence about losses due tofoxes. The cost associated with all aspectsof the management pr ogram should becarefully tabulated and compar ed with theperceived increase in pr oduction. Whereperformance indicators show that themanagement program is unlikely to r eachthe objectives, other causes of lamb lossneed to be car efully reconsidered. Thelandholder must also consider that strategic,targeted fox management was not ef fectiveand that mor e intensive control may berequired.


9. Implementingmanagement of foxdamage

Summary

While governments have endorsed theprinciple of beneficiary pays, it is not alwayspossible to clearly identify the beneficiary,especially where foxes are causing damageto both production and native fauna.Landcare and similar community-basedgroups can provide a useful mechanism inthese cases for developing a commonapproach and for determining appropriateinput of resources.

The Commonwealth, states and territorieshave a number of programs and otherinitiatives which can help agencies andland managers to add to the knowledge offox damage, to develop better managementstrategies and to help disseminate relevantinformation. These include the EndangeredSpecies Program, Feral Pests Program,Vertebrate Pest Program and the VictorianLand for Wildlife initiative.

Effective management of fox damagerequires local community support. Thecommunity needs to be aware of andunderstand the damage foxes cause andhow it can be addressed. Techniques forachieving this include brochures, field days,public addresses and pilot projects todemonstrate the effective strategies.

9.1 Introduction

Historically, the management of fox damagein Australia has r elied mainly on sporadiccontrol of foxes at the local level with littleor no infor mation about the associated costsand benefits. Although widespr ead bountyschemes have operated in the past ther e hasbeen no r eal attempt to assess their value.Based on overseas experience bounties ar enot an ef fective method for pr eventing foxdamage (Whitehouse 1977). Existinglegislation r elated to fox managementapplies largely to the types of poisons and

baits permissible for use (Section 6.2), andthe legal status of the animal as a pest. Infact, the only detailed strategies for foxmanagement in Australia ar e those inWestern Australia for pr otection of nativefauna and the national and state contingencyplans for eradication of exotic disease.

9.2 Role of governmentsand landholders

Commonwealth, state and terri torygovernments have endorsed the principleof beneficiary pays (Braysher 1993). Thedifficulty is in accurately deter mining thebeneficiary. For conservation r eserves, it isthe community, state or national, and theyshould pay. For agricultural pr oduction thelandholder is the beneficiary and shouldbear the bulk of the costs. However , thedifficulty arises wher e control over andabove what a landholder may r equire toprotect production is necessary to pr otectnative fauna. Similar conflicts can occurwhere private land abuts conservation landcontaining pests. In these cases the variousinterest groups should coordinate to developcommon approaches and to deter mineinput of r esources. Landcare and similarcommunity-based groups provide a usefulmechanism for this (Braysher 1993).

‘Most states and territoriesprovide a fox management

advisory service.’

Most states and territories pr ovide anadvisory service for managing foxes andother pests. They can also assist withpreparation of poisoned bait, but in manyparts of Australia this has been poorlycoordinated. Gover nment programs tomanage fox damage have, in general, beenconfined to national parks and natur ereserves in order to pr otect native wildlife.Where fox management is also essential onsurrounding cropping or pastoral land,government usually takes the lead inorganising the control and supply of poison(see Example 2, Braysher 1993 for theMurray Mallee of South Australia).


9


‘Government programs tomanage fox damage havegenerally been confined tonational parks and nature

reserves.’

The Commonwealth Gover nment has anumber of programs which can assist inmanaging foxes and other pests. Generally,the Commonwealth encourages studieswhich add to the knowledge of fox damageto wildlife and to the development ofsuitable control strategies. Those that ar erelevant to fox management ar e:

• Feral Pests Program (ANCA) — Thisprogram aims to develop and implementprojects in cooperation with otherCommonwealth authorities and state andterritory agencies to r educe the damagecaused by feral animals to native faunaand/or the natural envir onment, particu-larly in areas important for the r ecovery ofendangered species. Foxes, feral cats, feralgoats and rabbits ar e given priority as theseare listed as key thr eatening processesunder the Commonwealth EndangeredSpecies Protection Act 1992.

• States Cooperative Assistance Program(ANCA) — The aim is to develop natur econservation projects of national or inter -national significance in cooperation withthe states and territories. Elements of theprogram include wetlands conservation,conservation of migratory species andcontrol of envir onmental weeds.Additionally, the program covers educationand extension for the br oader area ofmanagement and maintenance of biodi-versity, and as such does not pr ecludeinvestigations of fox pr edation.

• Endangered Species Program (ANCA) —This pr ogram aims to ensur e thatendangered and vulnerable species andecological communities can survive andflourish, retain their genetic diversity andpotential for evolutionary development intheir natural habitat, and to pr event furtherspecies and ecological communities fr ombecoming endangered. Foxes have beenone of the priority ar eas for this pr ogram

in the past but with the cr eation of the FeralPests Program (FPP) in 1992–93, most feralanimal projects were transferred to the newprogram.

• Vertebrate Pest Program (Bureau ofResource Sciences) (see Introduction).

There are also initiatives at the state andterritory level with r espect to br oader imple-mentation of fox management strategies. InVictoria, for instance, fox contr ol is beingpromoted as an activity for LandCar e groups.The Department of Conservation andNatural Resources has joined with privateindustry in a ventur e to pr ovide a shelf-stablefox bait for poisoning (Foxof f® — AppliedBiotechnologies). Schemes to pr omote thevalue of private far mland as wildlife habitatsuch as Land for W ildlife in Victoria mayalso help implement fox contr ol measures.

9.3 Use of communitygroups

In the past, most fox management workhas been conducted either by gover nmentagencies (on public land) or by individualfarmers (private land). Almost all of themanagement has involved either poisoningor shooting and, generally speaking, theoperation has been a r eaction to perceiveddamage rather than a pr eventative measuretaken in advance.

Although community fox drives havebeen a longstanding tradition in some ruralcommunities, such initiatives ar e based moreon social and sporting outcomes rather thanupon a clearly defined aim to r educe foxnumbers for some economic or envir on-mental objective.

Given our knowledge of the movementof foxes and their ability to quickly r ecolonisesmall cleared areas, it is evident that smalland sporadic r eactive operations are unlikelyto give long-ter m respite from damage. Cost-ef fective management of fox damage,especially to protect vulnerable wildlife, islikely to r equire control operations whichcover relatively large areas so that immigrationcan be confined to buf fer zones on the


9

perimeter of the tr eated area. Implementationof such management r equires coordinatedeffort across the area to be tr eated.

‘Sporadic and small-scalecontrol operations are unlikely

to provide long-term respitefrom fox damage.’

The importance of gr oup action for theeffective management of fox damage needsemphasis. Based on experience with thegroup approach to rabbit management,groups should be r elatively small, involving10–50 landholders. Wher e the nature of thefox problem or the land type/land use variesmarkedly within a lar ge target area, it isadvisable to consider the for mation of sub-groups such that each smaller gr oup sharesa common appr oach and a common goal.Most importantly, the impetus for for mationof a gr oup should come fr om the communityitself and not fr om the pest contr ol authority.It is the function of the latter to encourageand facilitate gr oup formation but not toimpose it such that local landholders willhave no r eal sense of ownership of theproblem or of the pr oposed solution.

‘Control operations whichcover relatively large areas arerequired to protect vulnerable

wildlife.’

It is important that the damage causedby foxes is seen as a community pr oblem —not a pr oblem to be solved by gover nmentsor the next-door neighbour . In this context,it is necessary to pr omote the fact thatcommunity ownership involves mor e thanjust the landholders themselves. Under theprinciple of beneficiary pays, fox damageto wildlife, for instance, is a cost to the wholecommunity, not just those who actually ownor occupy the land.

Part of owning the pr oblem can beexplained or pr omoted in ter ms of anindividual landholder’s r esponsibility toneighbours. It is generally accepted that noperson has the right to inter fere with aneighbour’s legitimate business. This iseasily demonstrated in say, the case ofmarauding farm dogs which begin killing

sheep on neighbouring pr operties. Here,there is generally little dispute r egarding theresponsibilities of the dog’s owner — theyare expected to either r emove or destroythe offending animals. W ith foxes pr eyingon lambs, no such clear r esponsibilities exist.One farm running cattle, for example, mayprovide suitable cover for lar ge numbers offoxes which then kill lambs on a neigh -bouring sheep far m with few or no r esidentfoxes.

Unlike the damage caused by many otherpests of agricultur e or the envir onment, thatcaused by foxes to wildlife may not beimmediately evident. Very often, decline inwildlife populations is slow and insidious innature. In a situation wher e the damage hasbeen incremental over a very long period oftime and, mor e particularly, wher e it isexacerbated by other factors, land managerscan often fail to per ceive the true natur e ofthe problem. Indeed, as pointed out in othersections of this document, the measur ementof fox damage can be dif ficult. Even in thecase of fox pr edation on lambs, r ecentstudies (Section 3.2.1) suggest that simpleexamination of lamb car casses may not givean accurate measure of total losses to foxes.

‘Fox impact on wildlife affectsthe whole community — not

just those who actually own oroccupy the land.’

Thus, one of the first r equirements forsuccessful gr oup action is a generalknowledge of the local impact or at leastsuspected impact of fox pr edation in thedistrict. Following this, the gr oup will needsome appr eciation of the scope andmagnitude of the task ahead, particularly thefact that it is likely to r equire a long-ter mcommitment to management activities.Mapping of the ar ea is perhaps the simplestway to convey this infor mation. As anexample, many LandCar e groups put togethercomposite aerial photographs of their territory,and by using overlays, deter mine variousclasses of habitat or far ming country at risk.

Some of these gr oups are now showinginterest in digitised mapping and linking


into a computerised GIS. This appr oach hasconsiderable potential for i t canaccommodate an enor mous amount ofuseful information. Maps can be pr oducedat any r equired scale and the particularfeatures shown on those maps can be variedat will (Section 7.4.3). For instance, a foxmanagement group may r equire a mapwhich combines a particular vegetation type(for example, dense bush or high tussockswhich may be favour ed refuge areas forfoxes) with cadastral infor mation andinformation on the local distribution ofwildlife species considered to be at risk dueto fox predation. One of the major benefitsof this approach is the ability for individualland managers to supply infor mation to thedata bank and to get back fr om the systemdetailed maps of individual far ms showingthe features required. The landholder, underthese types of mapping schemes actuallybecomes the provider as well as the r eceiverof the mapping infor mation.

‘The impact of foxes on wildlifemay not be immediately

evident.’

One of the major pr oblems associatedwith the implementation of fox managementstrategies is deter mining the level of contr olactivity r equired to pr oduce somemeasurable and stable r esponse in thechosen indicator wildlife species. In fact, itwill require that those implementing foxmanagement gain some skills in measuringthe responses of particular pr ey populations.This is likely to be a dif ficult task and onewhere assistance fr om expert staf f in thewildlife management authority will berequired.

Landcare and similar community-basedgroups offer an ef fective mechanism foridentifying common objectives formanagement and to coor dinate action acrossa region. Most groups use a catchment-based philosophy and no longer think interms of single far ms. Many are now alsoinvolved in detailed mapping and thecollection of other data such as infor mationon native flora and fauna. These databasesare useful for planning and implementing

fox management. Examples of how acommunity group might coor dinate foxmanagement would include some or all ofthe following:

• surveys designed to identify the locationand abundance of wildlife speciesconsidered to be in decline and known tobe preyed upon by foxes;

• initial survey to deter mine the magnitudeof lamb losses to pr edation in the district;

• routine spotlight transect counts or othermeasures designed to give some generalindex of fox abundance;

• planning and execution of a coordinatedcampaign of bait-laying such that lar geareas of country ar e treated on a grid basis;

• where applicable, identification of fox densites on local maps so that subsequentfumigation of dens in the br eeding seasoncan be conducted in the r elevant areas;and

• where applicable, the inclusion into localmaps of known lay-up points for foxessuch as swamps, thickets and brackenpatches.

9.4 Community awareness

It is clear that the issue of har mful predationby both foxes and cats is now r eceivingmuch more attention in the media and thatcommunity awareness in this particular ar eais increasing. Feral and wild pest animalsand their impact upon the Australianenvironment are now popular school essaytopics or school pr ojects and more andmore media attention is being given to theproblem.

‘Community awarenessprograms usually concentrate

on problems rather thanpossible cures.’

Nonetheless, current communityawareness pr ograms often tend toconcentrate on per ceived problems ratherthan providing a detailed analysis of theactual problem including identification of

all major causes. W ildlife managementauthorities and those concer ned withvertebrate pest management need to fosterinformed debate on the impacts ofpredation, including fox pr edation. Thiswould involve explaining what we knowof predator–prey relationships and suchinformation as the dietary range of thepredator and other aspects of its biologywhich have some bearing on management.

Effective management of fox damage inany area that covers a mix of land uses willrequire local community support. T o achievethis the community needs to be awar e ofand understand the damage that foxes causeand how it can be addr essed. Currently inrural communities it can be expected thatattitudes toward foxes will range fr om indif-ference to the belief that they ar e the primarycause of lamb loss or wildlife decline.

‘Fox management requireslocal community support.’

A variety of techniques ar e available toassist information transfer and adoption ofappropriate practices. These includebrochures, media r eleases and publicaddresses which target the relevant audience.Probably one of the most ef fective educationtools is the establishment of smalldemonstration projects that involve therelevant community in the damageassessment, planning and implementation ofthe management pr ogram. Braysher (1993)outlines an example of such a pr ogrambetween the South Australian National Parksand Wildlife Service and the local far mingcommunity to conserve malleefowl intheSouth Australian mallee. First-handinvolvement is often a str ong motivatinginfluence to undertake appr opriate action.

Finally, in fostering community awar enessof the pr oblems caused by foxes in Australia(particularly in the ar ea of wildlife conser -vation), it is important to discer n betweenperceived problems and actual pr oblems.Actual wildlife benefits of fox managementare known, although only for a limitednumber of species in a limited range ofhabitats. Given this, major management

programs should not be pr omoted unlesseither good — or at least cir cumstantial —evidence is available to implicate the fox,or evidence by way of infer ence from otherstudies strongly suggests the involvementof foxes in some har mful predation. Forexample, the continued existence of a smalland remnant colony of r ock-wallabies in theVictorian Grampians might r easonably bethought of as being at high risk to foxpredation based on the fate of similarisolated rock-wallaby colonies in WesternAustralia, where effective fox contr ol led toa dramatic rise in population size of the pr ey.


9


10.Deficiencies in currentknowledge andapproaches

Summary

Apart from the relatively recent studies inWestern Australia, quantifiable informationon the damage foxes cause to native faunais lacking. While there is good reason to believethat foxes are having similar impact in otherparts of Australia, control strategies cannotbe planned without reliable data. The iden-tification of the range of species at risk is anarea where reliable information is neededboth in relation to predation by foxes andcompetition between foxes and native wildlife.There is also reason to believe that theeconomic losses due to lamb predation byfoxes may be greater than previously thought.Studies are required to quantify the losses.

Although a number of techniques can beused to minimise the harmful impact of foxes,there has been relatively little scientificassessment of these techniques. Withpoisoning, for instance, much moreinformation about the required baitingintensity and frequency, the timing of thepoisoning operation, the best toxin to use andthe likely impact on animals is needed.Likewise with den fumigation, there is a needfor more humane and effective fumigants.In the case of exclusion fencing, now usedin a number of important recovery programsfor endangered species, little scientific workhas been conducted on the cost-effectivenessof various designs.

There are a number of deficiencies in non-technical aspects of managing fox damagethat can be improved. These include widevariation between states and territories inthestatus and requirements to managefoxes,poor organisation and coordinationof management programs, the lack of acommunity or district approach, and ageneral failure to communicate to the generalpublic the scope and nature of the fox problemor potential problem in Australia.

10.1 Introduction

It is clear that mor e information is r equiredto deter mine the significance of foxpredation in Australia and, mor e specifical-ly, to define and impr ove techniques forminimising this damage. Until r elativelyrecently, the fox has not been a species thathas attracted widespr ead inter est inAustralia. Apart fr om studies in V ictoria(Newsome and Coman 1989) and r ecentwork in Western Australia, research on thefox has been sporadic. In contrast, it hasbeen extensively studied in Eur ope andNorth America because the fox is a majorvector of rabies. Since Australia is rabiesfree, and because for some time the fox wasnot perceived to be a conservation pr oblemor a significant thr eat to primary pr oduction,there was little incentive to study the animal.

Recently this attitude has changed con-siderably due to the gr owing informationabout the thr eat foxes present to native fauna.As a r esult the Commonwealth is supportinglarge-scale research programs on biologicalcontrol of foxes in Australia (Section 7.5.7).However this r esearch is long-term and high-risk, and even if this biological contr olapproach is successful, mor e conventionaltechniques will still be needed. Considerablework is r equired to improve the ef ficiencyand effectiveness of these techniques.

The Commonwealth, through ANCA, isalso supporting r esearch programs on con -ventional techniques. A major r esearchprogram is under way in W estern Australiainvolving the W estern Austral ianDepartment of Conservation and LandManagement and the APB of W A withfinancial support fr om Alcoa. The r esearchis aimed at deter mining the most appr opriatebaiting regime when 1080 is used for foxcontrol over lar ge areas of conservationestate. Specific aspects being addr essed are:

• assessing the ef fectiveness/conservationvalue of buf fer zones of 1080-baited agri-cultural land abutting conservation estate;

• determining the level of 1080 bait uptakein forested areas;



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• estimating fox densities in lar ge areas offorested conservation estate; and

• assessing the effectiveness of dif ferent 1080baiting frequencies when applied to lar getracts of forested conservation estate.

10.2 Specific deficiencies

10.2.1 Understanding predator–preyrelationships

Developments required

A more thorough understanding of the r ela-tionship between the fox and its pr ey isneeded. In particular, questions r egardingthe impact of foxes on vertebrates other thanmammals requires investigation. This mustinclude a better understanding of the wayin which other pr ocesses of extinction (thedestruction of wildlife habitat for example)impinge upon pr edation and vice versa. Arelated area is the important question of therole of rabbits in maintaining high foxpopulations, and the possible incr easedpredation pressure on wildlife when rabbitpopulations suddenly collapse due to factorssuch as myxomatosis or an ef fective rabbitpoisoning pr ogram. The r elationshipbetween fox density and impact on pr eypopulations also needs to be quantified.Another significant question is whether catswill replace foxes as wildlife pr edators if foxpopulations are reduced. These develop -ments are of fundamental importance, anduntil there is more precise knowledge of theconsequences of fox pr edation,management of foxes or fox damage willalways include a lar ge degree of speculation.

‘A greater understanding of therelationship between the fox

and its prey is needed.’

Wildlife management agencies needmore information on the benefits to wildlifeof fox contr ol. The adaptive managementapproaches used in Western Australia needto be trialled in other ar eas and for otherspecies.

Consequences

It would enable sensible and ef ficientallocation of scarce management r esourcesso that fox management or exclusion islimited to those species or particular habitatswhere predation is a definite thr eateningprocess.

10.2.2 Improvements to baitingtechniques


Chief amongst these is the need to deter minethe appropriate intensity, fr equency andtiming of baiting in much the same way ashas been done for rabbit baiting in Australia.This entails such elements as the numberof baits per hectar e, the number of baitingepisodes needed per year and the mostsuitable times to carry out such baitingexercises. These aspects ar e now beingaddressed by the ANCA-funded r esearch inWestern Australia.

‘The appropriate intensity,frequency and timing of

baiting needs to bedetermined.’

The other important aspects of baitingrequiring further r esearch are the pr esenta-tion of the bait, the choice of toxin and thepossible non-target ef fects of the technique,particularly associated with fox cachingbehaviour. With bait pr esentation, some ofthe factors r equiring work include baitpreference trials, particularly to cover possibleseasonal changes in fox diet, optimum sizeof baits, the value of burying baits, the valueof lures and, importantly, the biodegradabilityof the bait-toxin combination.

The issue of multiple bait take and theultimate fate of all r emoved baits also r equiresfurther r esearch. It is common at thebeginning of a baiting pr ogram to have lar genumbers of baits r emoved, disproportionateto the expected number of foxes. If surplusbaits are cached by foxes and r emain uneatenthere is a potential risk to non-tar gets.

Choice of toxin is an issue in some ar easwhere use of 1080 is not advisable. Ingeneral terms, 1080 must be r egarded as themost effective toxin currently available forthe Canidae although cyanide could beconsidered more humane. Experiences withthe use of cyanide baits for r esearch workin Western Australia suggest that this toxinis both highly ef fective and humane. Furtherstudies on the safety to human operators,non-target effects and how best to use thistoxin are required. Since fox contr ol in urbanand semi-urban areas is a gr owing issue,some attention to the development of a safebait for urban foxes is warranted. In all ar easof baiting research, the possible non-tar geteffects of the technique must be consider ed.Further investigation is needed to impr ovethe selectivity of the bait/toxin combina -tions and their methods of deployment sothat other wildlife species and domesticanimals are not put at risk.

Other important factors to be consider edinclude:

• the effect of long-term reliance on poisonsto suppress fox populations in inducingneophobia and bait-shyness. Ther e mayalready be evidence for these develop-ments in dingoes (D. Ber man, CCNT, pers.comm. 1994);

• the frequency and intensity of baiting inrelation to the size of the ar ea treated; and

• the use of buf fer zones and variations inbaiting regimes in dif ferent habitats.

Consequences

Improved efficiency and target-specificity offox baiting. More humane control of foxes.

10.2.3 Improved den fumigants


Den fumigation, although used widely forfox control in Europe, has rar ely been usedin Australia. With the curr ent interest incommunity land management initiativessuch as Landcare, it may well be that den

fumigation can be used as part of anintegrated program to control foxes. Thetwo fumigants curr ently being used forrabbit fumigation in Australia have anumber of shortcomings, chief of which isthe fact that they cannot be demonstratedto cause humane death. One possiblealternative, which should be consider ed asa den fumigant, is carbon monoxide, sinceit is generally believed to be a humane andeffective fumigant when used corr ectly.

Allied with the use of den fumigants isthe possibility of using the tarbaby techniqueat entrances to the br eeding dens (Ryan andEverleigh 1975). This technique is worthinvestigation since it would ensur e that anyfox visiting the den, but not necessarilyliving with the cubs, would be exposed tothe mixture of toxin and gr ease. However,this technique may have some pr oblems oftarget-specificity.

Consequences

Increased contr ol options for foxes,particularly in ar eas where poisoning is notadvisable. May pr ovide a mor e humanetechnique for fox destruction.

10.2.4 Fox-proof fencing and otherbarriers


With increasing concerns about pr edatorimpacts on thr eatened mammals in Australia,emphasis has been placed on the conceptof predator-proof enclosures as a means ofarresting the decline in some endanger edspecies. An example is the easter n barredbandicoot in Victoria.

A considerable investment has been madein predator-proof fences, and their ef fec-tiveness has r ecently been reviewed (Comanand McCutchan 1994) (Section 7.5.5). Themain issue concer ns its cost-ef fectiveness.It is possible, using exist ing fencetechnology, to pr oduce designs which ar eeffective against foxes. However the cost ofsuch fences is usually pr ohibitive, and many


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of the designs, particularly those employingenergised wires, suf fer from maintenanceproblems.

The evaluation of fencing thus involvesa matrix of the following: initial costs,maintenance costs, expected life, ease oferection, degree of ef fectiveness, suitabilityfor rough terrain, dangers to other wildlife,and wildfire hazards. This matrix of factorsthen needs to be assessed in r elation toother methods for pr otecting wildlife frompredators, such as the cost-ef fectiveness ofcontrolling predators rather than simplypreventing their access. An example is thesuccessful use of fox poisoning by Kinnearet al. (1988) in W estern Australia.

Consequences

The most suitable and cost-ef fective designsfor fox-proof fences can be deter mined forvarious types of terrain and habitat. This willbe of considerable importance in themanagement of some vulnerable, endanger edor locally endanger ed wildlife species.

10.2.5 Fostering public awareness

Deficiency

The damage caused by pest animals inAustralia has r eceived relatively little publicitycompared with other envir onmentalmanagement issues such as tr ee decline,salinity and the gr eenhouse effect. In part, thislack of public understanding of the pr oblemreflects a dearth of scientific knowledgeregarding the level and severity of pr edationand other negative aspects of foxes.Nonetheless, suf ficient knowledge of thepotential of fox pr edation to cause significantdamage, particularly in endanger ed speciesrecovery programs, is available to pr omote amuch wider discussion and communityinvolvement in the pr oblem. There is also,from the European experience, a good ideaof the potential significance of wild foxes asvectors for some strains of the rabies virus.Both of these negative values of foxes r equiremuch wider exposur e to the public.

Examples of how public awar eness ofthese problems or potential pr oblems mightbe raised include the pr ovision of a well-presented textbook on intr oduced predatorsin Australia and the inclusion or incr easedemphasis in school curricula of infor mationoutlining the har mful impact of foxes.Current community awar eness programstend to concentrate on per ceived problemsrather than a detailed analysis of the issueincluding identification of all major causes.

Consequences

An informed public, particularly in ruralareas, will be better able to understand thenature of fox pr edation on livestock andwildlife and to carry out ef ficient and target-specific control measures.

10.2.6 Ecology

Deficiency

Relatively little is known on the ecology ofthe fox in Australia (Chapter 2). Ther e is alack of infor mation in key ar eas such asregional differences in behaviour, reproduc-tive potential, mortality factors, and movementand responses to culling. Ther e is also anabsence of accurate data on populationdensities, attributable in part to a lack ofreliable census techniques. The importanceof this pr oblem ranges from the necessity tomonitor the presence of very small numbersof foxes in ar eas where previously they mighthave been absent, to high densities of foxeswhere the impact on native species needs tobe assessed.

The potential role of the fox as a competitorof native wildlife is poorly understood. Thisinformation is needed to pr otect native speciesthat may be at risk thr ough competition withfoxes (Section 3.1.7).

Consequences

With better ecological infor mation, it will bepossible to develop mor e specific foxmanagement strategies in dif ferent regions

and environments. It will also considerablybenefit the preparation of contingency plansfor fox management in the event of an exoticdisease outbreak (Chapter 4).

10.2.7 Organisation ofmanagement programs

Deficiency

At present, much of the management of foxdamage in Australia is r eactive andconducted by individual landholders. Ther eis relatively little emphasis on lar ger-scalecoordinated programs. If any r eal and lastinggains are to be made, it will be because foxmanagement is viewed in much the sameway as rabbit contr ol — viz. the key tosuccess being lar ge-scale managementprograms involving groups of landholdersor even whole districts. As is the case withrabbits, recolonisation of small, clear ed areasis likely to be rapid. Another importantdeficiency in organisation is the lack ofmeasurable goals in ter ms of r educing foxdamage and of benchmark data on whichto gauge progress towards any such goals.Indices or measures of changes in importantindicator species are required.

‘The best approach is large-scale fox management

programs which coordinategroups or even whole districts

of landholders.’

Consequences

Fox management will change fr om being asporadic and remedial technique carried outby individual land managers to one whichintegrates the control process over largerareas and achieves some lasting gains in acost-effective and measurable manner .

10.2.8 Legislation andadministration

Deficiency

It is clear that the administrative pr oceduresand legal status of foxes varies considerably

between the various states and territories(Section 6.2). Historically, the administrativeprocedures set in place to deal with foxpredation arose almost entirely from a con-sideration of the animal as a pr edator oflivestock. With a gr owing realisation that foxpredation is heavily implicated in the declineof some native species, a r eview of the legalstatus of the animal is now timely. As far aspracticable, legislation at state and territorylevel should be consistent so that ther e canbe a national focus on the pr oblem. TheVictorian Flora and Fauna Guarantee Act1988 and the Commonwealth EndangeredSpecies Protection Act 1992 are the exceptions.In particular, the requirement to pr epare andimplement Threat Abatement Plans under theEndangered Species Protection Act is a majoradvancement in the initiation of strategic foxmanagement. A concer n with these Acts isthat they provide no guidance to the scale andpattern of management operations which ar enecessary to address a thr eatening process.Such a scale could range fr om highly localisedto national. Without careful consideration thepattern and demand on r esources couldbecome disproportionate to the distributionof key endangered species. Guidelines for theselection of scale and patter n of actions withinThreat Abatement Plans should be pr eparedby relevant agencies. The pr ocess adopted bythe Department of Conservation in NewZealand for Himalayan thar , possums, andferal goat control is a useful guide (NewZealand Department of Conservation1993,1994,1995).

Closely allied to the need to r eviewlegislation is the need to ensur e that adequateattention is given by the r elevant vertebratepest control authorities to extension andtraining in the management of pr edatordamage. This is particularly so for V ictoriaand Tasmania, where there are major recentchanges in the management of pests. Anymove to use exter nal contractors for pestcontrol operations when they wer e previouslyperformed by vertebrate pest agencies, mustensure that standards are maintained and thatthe availability of trained operators is notdiminished.


Consequences

A more rational and mor e uniform set oflegislative pr ocedures to deal with theproblems caused by fox pr edation.Improvements in the dissemination ofinformation related to fox managementstrategies.


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APPENDIX A

Native species believed to beat risk from fox predation

The following list, although far fr omcomprehensive, gives some indication ofspecies at risk fr om fox predation:

Marsupials

Bilby, Macrotis lagotisBlack-footed rock-wallaby, Petrogale

lateralisBrush-tailed bettong, Bettongia penicillataBrush-tailed rock-wallaby, Petrogale

penicillataDibbler, Parantechinus apicalisEastern barred bandicoot, Perameles gunniiKowari, Dasyuroides byrneiLong-footed potoroo, Potorous longipesMountain pygmy possum, Burramys parvusMulgara, Dasycercus cristicaudaNumbat, Myrmecobius fasciatusRed-tailed phascogale, Phascogale caluraRufous hare-tailed wallaby, Lagorchestes

hirsutusSandhill dunnart, Sminthopsis psammophilaSouthern brown bandicoot, Isoodon

obesulusSpectacled hare-wallaby, Lagorchestes

conspicillatusWestern ringtail possum, Pseudocheirus

occidentalisWestern quoll, Dasyurus geoffroiiYellow-footed rock-wallaby, Petrogale

xanthopus

Rodents

Central rock-rat, Zyzomys pedunculatusDusky Hopping mouse, Notomys fuscusHeath rat, Pseudomys shortridgeiPlains rat, Pseudomys australis

Birds

Bush thick-knee, Burhinus magnirostrisGround parrot, Pezoporus wallicusLittle penguin, Eudyptula minorLittle tern, Sterna albifronsMalleefowl, Leipoa ocellataNight parrot, Geopsittacus occidentalisNullabor quail-thrush, Cinclosoma alisteri


APPENDIX B

Technique for themanufacture and use ofcyanide capsules

The technique involves laying dry,commercial grade sodium cyanide (NaCN)powder encased in a capsule comprised ofa mixture of 90% paraf fin and 10% micr o-crystalline wax. This combination of waxesproduced a robust yet brittle capsule, witha relatively high melting point. The twowaxes are melted together and heated to atemperature just below boiling. Stainlesssteel rods are placed in a lubricating agent ofsoapy water and then dipped briefly in theheated wax. The wax capsules ar e thenprized off the r ods. Each capsule isapproximately 8 mm in diameter and 50 mmin length. Capsules ar e then inverted and leftto dry at r oom temperature for 48 hours.

The capsules ar e two-thirds filled, approx-imately 1.0 g, with NaCN powder . A cottonwool plug, through which a length of loopedwire (hair pin) is inserted, is placed into thecapsule at its open end. Melted wax is thenused to seal the capsule. Next, cyanidecapsules are placed in water to wash of f anyexcess cyanide and to ensur e that they ar ecorrectly sealed. NaCN r eadily absorbs andreacts with moisture causing caking in thecapsules. Dry, powder ed NaCN is rapidlylethal but caked NaCN can be spat out sothe animal escapes (Connolly et al. 1986).Because the capsules ar e only partially filledit is possible, by gently shaking thecompleted unit, to see whether the cyanidepowder is fr ee-flowing. These capsules ar ethen air-dried and secur ely stored.

Two capsules are used at each baitstation spaced 200 metr es apart along tracksor firebreaks. Each capsule is tether ed to aburied plate (or other suitable anchors)using a fishing wir e trace which is attachedto the wir e loop embedded in the capsule.When sited, each capsule is coated with anappropriate lure dispensed from a squeezebottle.

Anchoring the capsule pr events the foxfrom carrying of f an intact capsule. If a foxpicks up a capsule with the intention ofmoving off, the capsule ruptur es when itreaches the end of the tether and cyanidespills into the fox’s mouth. This arrangementhas made the pr ocedure more reliable, andsafer to use as it pr events intact capsulesfrom being carried of f.

‘Brit t i l ised’ capsules ar e of theconventional gelatine variety which ar efreeze-dried after treatment with acetoneor formaldehyde. The dehydration pr ocesscauses the capsules to become brittle andthe chemical tr eatment causes a cr oss-linkage in the gelatine which makes itresistant to r ehydration. The capsules ar ethen coated with a mixtur e of paraf fin waxand animal tallow. Captive trials haveshown that foxes will easily ruptur e thecapsules, but the exact field pr esentationof the bait is not yet decided (C. Marks,DCNR, Victoria, pers. comm. 1995).

Wax capsules can also be pr esented in aburied bait system utilising a capsuledeployer. The deployer is an all har dwoodconstruction consisting of two holdingblocks attached to a base plate. The holdingblocks are a set distance apart to allow theplacement of half a Foxof f Free FeedEconobait. Holes in the holding blocksallow a wax capsule containing powder edsodium cyanide to be placed horizontallyabove the Foxof f. The capsule is secur edinto position with a locating pin whichpasses through the wir e loop embedded inthe capsule. Tent pegs hammer ed throughholes in the base plate ar e used to pr eventremoval of the deployer fr om the bait site.The capsule deployer of fers a degree ofprotection to the capsule during excavationand it pr events removal of the intact capsulefrom the bait site. The fox is for ced to br eakthe capsule befor e it can access the Foxof fEconobait (C. Marks, DCNR, V ictoria, pers.comm. 1995).


APPENDIX C

Instructions for the use ofFOXOFF® baits

LAND PROTECTION BRANCH,DEPARTMENT OF LANDS,

QUEENSLAND

(revised 25/10/94)

Foxoff baits are a meat-based manufactur edbait for the contr ol of canid pests, particularlyfoxes. The poison is absorbed into the centr eof the bait and defined by the pr esence ofred dye. 60 and 35 gram versions ar eavailable. READ THESE INSTRUCTIONSBEFORE USE.

Vertebrate pest species

Baits are to be used for no purpose otherthan for the destruction of foxes unlessotherwise approved by the Dir ector.

Minimum distances

All baits must be distributed on the landdescribed in the indemnity for m only.Unless otherwise approved by the RegionalInspector, baits must not be laid:

• WITHIN 1 KILOMETRE of any habitation(habitation includes any dwellingexcluding the owner’s), or public amenity,or

• WITHIN 5 KILOMETRES of a town ar ea,or

• WITHIN 5 METRES of a fenced pr opertyboundary, or

• WITHIN 50 METRES of the centr e-line ofa road

• On properties smaller than 40 hectar es*

* With the appr oval of the RegionalInspector, baits may be used on smallerproperties, i f cooperation betweenneighbours al lows consolidation oflandholdings for the purpose of deter miningthe minimum property constraints.

Unless approved by the r elevant localauthority, baits must not be laid on anystock route or reserve for travelling stock.

Notification to neighbours

Notice must be given of the intention tolay baits at least 24 hours prior to thecommencement of the poisoning pr ogram.Notice must be served by mail or dir ecttelephone on every r esident and/oroccupier of the land adjoining or havingfrontage to the holding, or ar ea on whichpoison baits ar e to be laid.

In general, fox contr ol will be mor eeffective if action is taken over a wide ar ea.Thus it is appr opriate for neighbours tocooperate in coordinated campaigns. Thisreduces the bur den on individuallandholders, achieves a gr eater control area,reduces the rate of r einfestation and enablessynchronised action and pr ecautions withinan area.

Warning signs

When baits ar e laid and while baits r emainpresent on the baited ar ea, poison signswhich are provided with the Foxof f productmust be placed at all entrances to theproperty and at the extr emities of propertyboundaries fronting a public thor oughfare.Poison signs must be r emoved once thepoisoning campaign is completed.Additional large plastic poison signs ar eavailable from Lands Department of ficers.

Bait storage and retrieval

While the 2–3 week pr ogram is under wayand while additional baits ar e required toreplace those at sites wher e bait take hasoccurred, baits may be stor ed in a dry lockablearea, away from children, pets and foodstuf fs.Foxoff does not r equire refrigeration.

All baits which have not been taken, andany baits supplied which have not been used,should be collected and destr oyed by incin-eration or deep burial at the end of the baitingcampaign.


In any case, all baits supplied shouldbe used or destroyed within one monthof supply. LONG-TERM STORAGE OFBAITS IS STRICTLY PROHIBITED.

Safety precautions

The 3 milligram dose of fluor oacetate (1080)poison used in the Foxof f bait is pr eciselycontrolled to pr ovide a certain lethal doseto the largest fox and is also adequate tokill most small to medium-sized dogs andcats which ingest a bait.

However, the dose in a single bait isgenerally below that necessary to kill mostnative animals, bir ds and reptiles due totheir higher r esistance to this poison.Approximately 8 baits eaten would pr ovidea lethal dose to a sheep and 67 should belethal to a cow. Sheep show no inter est inbaits. Cows occasionally investigate sand-marked bait stations.

Extensive r esearch in a variety ofhabitats has shown that very few animalsother than foxes and dogs ar e likely todig up and eat Foxof f baits. Thus, ther e isa high safety mar gin in r espect of dangerto non-target animals when baits ar e usedas directed.

Nevertheless fluoroacetate is toxic toall species including man and there isno known antidote. Dogs ar e highlysusceptible so it is important to r estrainworking dogs and pets and adviseneighbours and guests while baitingcampaigns are under way.

HANDLE BAITS WITH CARE ANDCAUTION

It is essential that baits ar e:

(a) kept away fr om food, pet food and foodpreparation areas

(b) kept away from children and pets andworking animals

(c) disposed of safely by deep burial(preferably in wet hold mor e than 50cm deep) or by incineration.

Following the use of bait, destr oy thedisposable gloves pr ovided and washhands before eating, drinking or smoking.Empty bait trays can be disposed of in alocal authority landfill or buried in a deephole.

Regional Inspectors or other authorisedpersons may deter mine addit ionalconditions and r estrictions on use if localcircumstances pose additional risks. Thesupply of baits may be r estricted if localrisks are considered to be unacceptable.

If in doubt always seek expert advicefrom your local Lands Departmentofficer.

In case of emer gency the QueenslandPoisons Information Centre number is(07)253-8233.

Degradation of Foxoff baits

Foxoff baits have been for mulated to remainstable while in original packaging. Howeveronce placed in moist soil the baits absorbmoisture and this allows the toxin to bedegraded to har mless residues by commonsoil bacteria and moulds. Ther e is minimallong-term environmental hazard from theuse of these baits at buried placements.

The rate at which the baits degrade willvary with soil moistur e and temperatur e.In controlled tests, baits in dry soil r etained75% of their toxin after two weeks wher easin wet soil toxin r educed to 21% by twoweeks.

Despite this degradation featur e, it isrecommended that all bait stations ar emarked (for example with spray mark ondropper posts, or ribbon tied to a tr ee orfence) to facilitate r egular checking andreplacement of baits taken and r ecovery ofbaits not taken at the end of the pr ogram.

Placement of baits

Foxoff baits should be buried just beneaththe surface within a shallow hole (8–10 cmdeep) and cover ed with soil. Foxes ar e


readily able to find and excavate buriedbaits whereas other animals or stock showlittle or no inter est.

Baits should be placed at intervals of atleast 200 metres, usually along inter nal fencelines or vehicle tracks. Placement of baitsclose to each other will r esult in several baitsbeing taken by a single fox. Since only onebait is needed to kill a fox, the uptake ofseveral baits by the same fox should beminimised.

Use of lure trails

The use of lur e trails such as car cass dragsor other scent markers is NOT necessary.While the use of lur e trails does r esult inmore baits being found in the early phaseof the program, this may be due to somefoxes progressing along the trail to findseveral baits.

Lure trails may be used if it is necessaryto complete the baiting pr ogram over ashort period, but it will usually be necessaryto replace baits several times at sites wher ebaits are taken (see below).

Bait replacement

Since the action of fluor oacetate in the foxis delayed, the fox r emains active forapproximately four hours after taking a bait.During this time foxes may sear ch foradditional baits and r eturn to lairs or densbefore succumbing to the toxic ef fects.Carcasses are seldom found near to baitstations but may be found in gr oups in longgrass or other cover eventually.

Fox mark sites of baits by urinating andmay leave a pointed scat at the bait station.Other foxes can visit the same station sofor effective control it is necessary to r eplacebaits several times at some sites. The extentto which this is r equired depends upon:local fox density; location of the station (forexample, near a major thor oughfare);surrounding habitat (for example, for est,swamp, creek); presence of lambs; and levelof control undertaken by neighbours.

Just one r ound of bait placement willgenerally NOT be suf ficient to kill all foxes.Bait replacement is necessary in mostsituations.

Bait density

This requires local advice but about 50 baitswill be needed per 400 hectar es (1000acres). This allows for a fox density of aboutfour foxes per squar e kilometre, for somebaits to not be found and for some foxesfinding more than one bait.

Replacement should continue until takestops. This often shows that the true foxproblem is gr eater than anticipated. Foxdensity may exceed eight foxes per squar ekilometre in some ar eas.

Free feeds

Unpoisoned ‘ f r ee-feed’ bai ts ar emanufactured to allow for the testing ofnon-target risk in sensitive ar eas, prior toplacement of poisoned baits. Fr ee-feedbaits are buried and fine damp sand isspread over a one-metr e diameter ar eaaround the bait station. Examination andsweeping of the sand every mor ningenables the detection of the tracks ofanimals which visit the station and/or takethe bait.

Extensive research has shown that inmost farming areas the risks to non-tar getnative animals is so low that the pr e-testingwith free feeds is not necessary. Seekadvice from your local Lands DepartmentOfficer if there is a special concer n aboutnon-target risk.

Fate of carcasses

The toxin in a fox car cass is destr oyed asthe carcass putrefies and bacteria degradethe toxin to har mless residues. It is unlikelythat any animal can r eceive a secondarypoisoning from eating a fox car cass. Forexample it is estimated that an eagle wouldneed to eat appr oximately 13 wholecarcasses to receive a lethal dose.


Carcasses do not need to be r ecovered.Many foxes will r eturn to lairs or dens befor esuccumbing to the toxic ef fects of the poison.Such carcasses are not easily found.

The key to responsible and effective use of baits is toplan and implement a thorough program, with baitreplacement and proper spacing. Best results areobtained if cooperative campaigns are conductedby neighbours and Landcare groups. Ensure thatpets are protected and neighbours are properlynotified. Seek advice if any aspect of these instructionsis unclear.


APPENDIX D

Criteria for eradication

Eradication is the per manent removal of allindividuals of a species fr om a defined ar eawithin a defined time.

There are three essential criteria whichmust be met for eradication to be possible(Bomford and O’Brien 1995). If all thr eecriteria cannot be met, eradication shouldnot be attempted:

• Foxes can be killed at a rate faster thanreplacement rate at all densities. Asthe density declines it becomesprogressively more difficult and costly tolocate and r emove the last few animals.

• Immigration can be prevented. This ispossible for of fshore islands or smallmainland populations which ar egeographically isolated, or wher ecompletely ef fective barriers can beerected and maintained, such as well-maintained fox-proof fences.

• All reproductive foxes are at risk fromthe control technique(s) used. If someanimals are trap-shy or bait-shy, thr ougheither inherited or lear nt behaviour, thenthis sub-set will not be at risk.

There ar e three additional criteriaidentified by Bomford and O’Brien (1995)that need to be met for eradication to bepreferable to long-ter m fox control:

• Foxes can be monitored at very lowdensities. This can be dif ficult to achieve.

• The socio-political environment issuitable. For example, if certain gr oupsobject strongly to the eradication of foxesthey can dir ectly thwart or politicallyinfluence the program.

• Discounted cost–benefit analysisfavours eradication over control.Discount rates are used to estimate thevalue of futur e benefits against the costsof actions in curr ent dollars. This criterionis difficult to meet because of the highinitial cost of eradication and becausebenefits accrue over a long period. At high


discount rates, eradication is unlikely tobe cost-effective. Eradication has a lar geinitial outlay but, if it can be achieved,there are no continuing costs apart fr ommaintaining the outer pr otective boundary.For cost-ef fective eradication, eachsituation where eradication is technicallyfeasible should be assessed to deter minewhether eradication costs outweighdiscounted benefits.


APPENDIX E

Best practice extension inpest management

Quentin Hart and Dana Kelly

Achieving sustainable land management,including pest management, can befacilitated by new appr oaches to extension.Traditionally, extension has been definedas the dissemination of infor mation. In thisdefinition, it is seen as the link betweenthe producers of infor mation (researchersand others) and the end-users of theinformation (generally land managers).Researchers, public policy makers andindustry tend to r efer to research transfer,technology transfer or infor mation diffusion.Bennett (1993) emphasises the need formutual interdependence and cooperativeaction combining these two appr oaches. Ifextension is to achieve adoption, it mustfacilitate understanding and involve aparticipatory rather than pr escriptiveapproach.

Some characteristics and principlesinherent in innovative extension pr ogramsare:

ownership;

benchmarking;

participatory learning based on principlesof adult lear ning;

equity and respect for everyone’s views(Kelly 1995);

problem definition with stakeholderconsensus (Ison 1993);

client driven or r esponsive to the needsof clients (McGuckian and McGuckian1994);

consider the whole pr operty or wholeagribusiness chain (McGuckian andMcGuckian 1994);

incorporate processes to create learningopportunities that lead to locallymeaningful and adaptive changes (Ison

1993), that is, ‘lear ning by doing’ (Section8.4.5 and Walters and Holling 1990); and

incorporate an evaluation strategy toensure the pr ogram is flexible andresponsive to exter nal changes such asthe environment or market (Kelly 1995).

Decreasing state government resourceslimit the ability of extension workers totarget individual land managers. Landcar egroups provide a partial solution to thisproblem in that they allow extensionworkers to tar get gr oups rather thanindividuals, and the infor mation dif fusionprocess within these gr oups is r elativelyrapid. The gr oup approach of fered byLandcare can also be used to developregional rather than individual managementplans for pest management (Chamala andMortiss 1990).

Extension should not dictate solutions butprovide the underlying technicalinformation and decision-makingframework from which land managers candraw their own conclusions. In this way,both government and land managers willhave a gr eater understanding of thecomplexity of the pr oblems and the possiblesolutions. Such participatory lear ningapproaches also pr ovide land managerswith ownership of the pr oblems andsolutions, and this facilitates adoption.

Involving land managers as co-lear nersand co-researchers is being encouraged indemonstration projects currently supportedby the Vertebrate Pest Program (VPP) of theBureau of Resource Sciences. The VPP fundsstate and territory gover nment agencies andLandcare groups to deter mine best practicepest management for a particular ar ea. Theprojects are generally large-scale field trialsinvolving several pr operties and comparingseveral management strategies. Rather thansimply providing land for the r esearch, theland managers ar e integral parts of theprojects and help deter mine managementoptions which ar e practical andeconomically sensible for their particulararea. Their involvement also facilitates thedissemination of project findings to other


land managers. One of the r oles of extensionis to maintain the momentum of suchprojects once gover nment funding ceases.

Relevance of infor mation to the landmanager in a framework of whole-pr opertymanagement needs to be consider ed byextension workers. Pest damage is a singleand often minor issue amongst a wide rangeof management considerations a landmanager has to contend with. This isparticularly true for pests which inflict majorbut infrequent damage — for example,mice. Pest management is peripheral to mostland managers’ major activities, and theirmotivation relates to current rather thanpotential damage (Salleras 1995).

Extension workers and r esearch workers‘must be able to understand the goals andreasons for motivation or otherwise of thevarious human stakeholders as well as thehabits and habitat of [the pest animal with]the most ef fective solutions [being] achievedby examining dif ferences in the humandimension rather than concentrating on thepest’ (Salleras 1995).

The above assertions by Salleras, a ruralland manager fr om Queensland, ar eprobably a good r epresentation of theattitudes of many land managers andprovide an insight into ef fective extensionmethodology. Extension should:

offer concise infor mation specific toregional needs;

of fer a framework for makingmanagement decisions based on genericinformation combined with localobservation;

offer a range of options rather than beprescriptive;

take account of the availability of pestmanagement tools (for example, GlobalPositioning Systems and bulldozers forwarren ripping) within a r egion so thatrecommended control techniques ar eappropriate;

take a whole-pr operty managementapproach by recognising that managers

have to allocate budgets to deal with manyrisks and opportunities and ar e rarely ableto fund pest contr ol at optimal levels.Given limited budgets, the solution is touse cost–benefit analyses, which ar erelevant to the local ar ea, to optimisewhere, when and how much contr ol isconducted. As part of this, pest damageshould be quantified and financialsituation of land managers should be takeninto account where data ar e available todo this (see Appendix B); and

ideally, implement local field trials, andfrom these coor dinate r egionalmanagement strategies to achievemaximum (and hopefully long-ter m)adoption.

Computer technology may pr ovide apartial solution to decr easing resources forphysical extension. It will enable pestmanagement information to be pr ovidedelectronically and r eadily updated. Thisinformation can be linked to decisionsupport systems to lead landholders step-by-step thr ough a pr ocess of ‘self-assessment’ so that they may deter mine thebest management options based on theirown on-ground observations.

The potential value of these systemsdepends entirely on the extent to which landmanagers adopt such technology. In theforeseeable future, adoption rates of bestpractice pest management, which ar ecurrently low and vary between localities,will depend on extension and r esearchofficers working with land managers todetermine what best practice is for theirsituation and becoming actively involvedin its implementation.


APPENDIX F

This appendix r efers to feral pigs, but theprinciples apply equally well to fox manage -ment.

Economic framework forferal pig management

(After Bomford and others 1995)

Land managers who wish to deter mine theoptimal economic strategy for managing aproblem caused by feral pigs could use thestepwise approach outlined in this appendix.We recognise that managers will haveincomplete knowledge of the infor mationnecessary to fully complete many of thesesteps. Nonetheless, the exer cise of attemptingto complete the pr ocess, and recording theassumptions and best guess estimates thatare made, may pr ove a useful aid to decisionmaking for feral pig management.

Step 1 — Desired outcomesIdentify desired outcomes and estimate adollar value for each of these. Wher e

outcomes are commodities, such asincreasing lambing per centages, thisshould be r easonably easy. Wher eoutcomes are difficult to measur e, suchas reduced land degradation, or intangible,such as incr eased biodiversity, landmanagers may be obliged to estimate howmuch they consider is an acceptableamount to spend to achieve that outcome.

Step 2 — Control options

List all control options and how much theywould cost to implement. Contr ol optionscan be dif ferent techniques orcombinations of techniques, or dif ferentlevels or fr equencies of application oftechniques (Section 7.6). It is importantthat the options for contr ol are expressedas activities that a manager can selecteither to do or not to do.

Step 3 — Density-damagerelationships

Estimate the relationship between pestdensity and damage for each r esourcedamaged by the pest (Figur e B1). For

Figure B1: Possible r elationships between pig density and the damage they cause. Line A isthe relationship shown in Figur e 9 and line B that shown in Figur e 10. Line C might occur if, forexample, only still-bor n lambs are preyed on by feral pigs at low densities, but if pig densityincreases, they start to kill healthy lambs.


example, if pigs ar e reduced by 50%, howmuch will this incr ease lambingpercentages. There may be interactionsbetween pest density and other far mmanagement practices which will need tobe taken into account. For example theincrease in lambing per centage caused byreducing pig densities by 50% may varywith dif ferent levels of availability ofshelter for lambs.

Step 4 — EfficacyEstimate the ef ficacy of each contr oloption. That is, how much will a giveneffort using a particular contr ol optionreduce pig density.

Step 5 — Cost–benefit relationshipsUse the infor mation from Steps 1–4 toestimate costs and benefits ofimplementing each contr ol option,including options which combine mor ethan one technique. Costs will be the cost

of implementing each contr ol option, andmay include costs of monitoring pests andplanning. Benefits will be the value of thereduction in damage to the valuedresource caused by implementing contr ol(that is the desir ed outcomes listed underStep 1 above), plus any pr ofits (forexample, those made fr om selling pigs orfrom allowing hunters on the pr operty).

Different pest management options willgenerate a variety of cost–benefitrelationships. Estimates of benefits andcosts can be discounted back to netpresent values (usually using a discountrate equivalent to the inter est rate thelandholder pays on financing the contr oloperation). This will r educe the value ofcosts and benefits accruing in the distantfuture relative to those accruing in the nearfuture.

Figure B2: Marginal analysis plotting both incr emental changes in the cost of r educing pigs toa given density and incr emental changes in the cost of damage caused by pigs at a givendensity against level of contr ol activity. Wher e the two lines cr oss is theor etically the optimallevel of pest contr ol. At higher levels of contr ol beyond this point, costs will exceed savings inreduced damage.Note: The x-axis units are for control effort (for example, dollars spent on control, hours ofshooting or trap nights) not pig densities.


Step 6 — Marginal analysis.Plot both the incr emental change in thecost of pig contr ol and the incr ementalchange in the cost of damage caused bypigs against the level of contr ol activitycontemplated (Figure B2). Where the twolines cross is theoretically the optimal levelof pest contr ol. Further increases in controlactivity do not cause commensuratereductions in damage, so at higher levelsof control beyond this point, costs willexceed savings in r educed damage. Anexample of marginal analysis for shootingferal pigs fr om helicopters is pr esented inFigure 20.

The problem for managers is that, becausethey often do not have good infor mationon the damage-density r elationship, it ishard to estimate the optimal contr ol point.Further, even if they can make a goodguess, it is not usually practical with mostcontrol techniques to simply cut of f controlefforts at some pr e-determined pig density.It is preferable to have a range of contr oloptions ranked along the x-axis, with theirassociated cost and benefit values forimplementation, so a manager can selectwhich option is optimal. For example,different frequencies of shooting could beput along the x-axis.

Step 7 — Pay-off matricesConstruct a table listing all the contr oloptions and their associated costs andbenefits (economists call this a pay-of fmatrix). For example, Section 8.8.3compares the costs and benefits of twocontrol strategies — shooting pigs fr omhelicopters or poisoning with 1080.Managers may wish to construct dif ferentmatrices for dif ferent conditions, such asdifferent stocking densities, seasonalconditions, or commodity values for wool,lambs or pigs. Managers will also need toconsider time-scales when constructingthese matrixes — what time span iscovered and how will this af fect costs andbenefits?

These matrices can then be used to selectthe option(s) which best meet themanagers’ goals. If the manager is risk

averse, the best options will be those thatbring in r easonable returns (benefits inrelation to costs) under the widest rangeof conditions (that is, in most seasons andwith a wide range of commodity prices).If the manager’s priority is to maximiseprofit, the preferred options will be thosethat are likely to give the highest r eturnson investment, even though ther e may besome risk of having no r eturns or even aloss if the seasons and prices go badly.

Payoff matrices can also be used by a landmanager to compar e retur ns oninvestment in pest contr ol with returns onusing the money for some other purpose,such as fencing, new stock watering holesor fertiliser.

Steps 1–7 complete the basic model. Themodel can be made mor e accurate byadding additional features. Incorporation ofsuch additional features will make the modelmore complex, but including at least someof them may be necessary to make itaccurate enough to be useful.

One way of impr oving accuracy may beto replace single estimates with a range ofpossible values, and give associatedprobabilities for each value in the range.

Managers may also wish to add additionalfeatures to the model such as:

Social benefits could be included in Step 1,such as:

— off-site ef fects and good neighbourrelations;

— biodiversity and endangered speciesmanagement in agricultural ar eas;

— retaining rural communities; and

— animal welfare management.

Risk management for spr ead of disease bypigs could also be included in Step 1.

Effects of government intervention couldaffect value of benefits (in Step 1) or costs(in Step 2).

Commercial harvest of feral pigs, as analternative to contr ol as a pest, could beincluded as a contr ol option in Step 2.


Indirect effects of pest contr ol (for example,controlling pigs may lead to an incr easein rabbit numbers) could be included asinteraction effects in Step 3.

The form in which benefits come may besignificant to a manager (Step 5). Forexample, cash ‘bonuses’ fr om the sale offeral pigs may be mor e attractive asimmediate cash for spending, than futur emoney fr om incr eased lambingpercentages, which may be committed inadvance to servicing debts or meeting far mrunning costs.

Much of the infor mation needed to followthe steps outlined in this appendix is notavailable. Some projects being funded bythe Vertebrate Pest Program in BRS aim tocollect some of these data.

Index

1080 poison, 4, 32, 33, 34, 36, 37, 46, 48, 53,73–75

attitude of ANZFAS, 53–54coordinated campaigns in V ictoria, 60differences in tolerance, 74effect on native car nivores, 3further study r equired, 107increased use in NSW , 62lethal efficacy, 74–75meat baits, 59–60recommended dose rate, 74use during low fox pelt prices, 54–55use in NT, 58use in Qld, 59use in WA, 59

research, 106–107see also Foxof f

abbreviations see acronyms and abbr eviationsAborigines fire regime, 35abundance of foxes, 70–71

see also densityacronyms and abbr eviations, ixadvisory service for fox management, 101aerial photographs, 69, 103Agriculture and Related Resources Protection

Act 1976, 58agriculture

damage from foxes, iii, 1assessment, 65–67;hypothetical example of strategic

management, 98–100performance indicators for pr oduction, 93

amphibianseffect of fox pr edation, 5survey techniques, 64

Anangu Pitjantjatjara Aboriginal Land Council,consultation, iii, viii

animal welfare, 48, 49–54fox control/harvesting, iv, 54–55opposition to dogging, 82use of steel-jawed traps, 4use of strychnine, 54use of traps, 82

see also humane techniquesanticoagulant, 76

definition, xAustralia and New Zealand Envir onment and

Conservation Council, viii

Australian and New Zealand Federation ofAnimal Societies (ANZFAS), 49

attitude to curr ent feral animalmanagement, 93

support for fertility contr ol measures, 86Australian Capital Territory, ACT Parks and

Conservation Service, 59Australian Conservation Foundation,

consultation, iii, viiiAustralian Nature Conservation Agency

(ANCA)Endangered Species Program, 102Feral Pests Program, 102management of feral animals, 58research into impr oved baiting techniques,

107role in preparation of the guidelines, iii, viiiStates Cooperative Assistance Pr ogram, 102

Australian Veterinary Association, viiiAUSVETPLAN Disease Strategy for Rabies, 47

baitsachievable rates of population r eduction, 47aerial baiting, 78–79

vaccine baiting, 46bait materials, 77–78baiting procedures, 80–81baiting systems, 46, 73–81buried baits, 78chemosterilants, 46concealment, 78free feeding, 81frequency & intensity, 79improvements to baiting techniques,

107–108manufactured baits, 78meat baits, 59multiple bait take, 107neophobia & bait shyness, 108recolonisation, 79–80RSPCA attitude, 50scent trails, 80surface baits, 77–78use in times of low fox pelt prices, 55

see also poisoningbandicoots, 32, 36, 64

eastern barred bandicoots, 60effect of 1080 baits, 3viewing by the public, 40

battues see fox drivesbest practice, 7–9


Bettongia penicillata see bettongsbettongs, 36

effect of 1080 baits, 3, 33effects of foxes, iii, 31, 32–33population recovery, 41, 79predator removal experiments, 31, 32–33viewing by the public, 40

biodiversity considerations, 3, 88biological control agents, 63, 86

see also immunosterilitybiology of the fox, 1, 18–26birds of prey

fox predation, iii, 15birds

effects of fox pr edation, 5ground parrot, 36ground-nesting birds, 64little terns, 60lyrebirds, 60survey techniques, 64

bounty schemes, 3, 11, 13, 14, 56–57, 80, 100see also Foxlotto

brittilised capsules, definition, xsee also cyanide

buffer zones, 102–03Bureau of Resour ce Sciencesrole in the guidelines, iii

see also Vertebrate Pest Program

cadastral information,104definition, x

Canis lupus, 16cannibalism, 24carbon monoxide, use as a fumigant, 51carrying capacity, 45, 79–80, 98

definition, xcase studies

agricultural production area, 90conservation area, 90

Catchment and Land Protection Act 1994, 60cats see feral animals, catscattle, impact of fox pr edation, iii, 39chloropicrin, use as a fumigant, 51–52, 83chuditch, 36commercial harvesting of foxes, iv, 8, 27, 38,

41–42, 54–55, 92price of fox pelts, 27, 41–42Commonwealth see governmentscommunity attitudes, 4

awareness of harmful predation, 104–105,109

community-based schemes to contr ol foxes, 3,9, 101–104

community problems, 103demonstration projects, 105information transfer, 105mapping, 103–104shooting, 59see also LandCaresee also Landcare

conservation areasagencies need to assess fox damage, 2assessment of pr ogram, 95case study, 90hypothetical example of strategic

management, 95–98payment problems, 101

conservation performance indicators, 93consultation on the guidelines, iii, viiicontrol techniques, 3, 4, 8, 45, 63, 72–87

coordinated campaigns in V ictoria, 60fertility control 85–87maintenance control, 91relationship between fox & rabbit contr ol,

27, 37RSPCA attitude, 50urban foxes in Qld, 60use of traps, 4, 45, 82–83water barriers, 84–85

see also individual techniquesCooperative Research Centre (CRC) for

Biological Control of Vertebrate PestPopulations, 86

costs of contr ol, 40, 88–89, 101cost-benefit relationships, 91fencing, 108–109fertility control drugs vs poisons, 86

coyotes, 19crisis management, 8CSIRO, Division of W ildlife and Ecology, 64cyanide, 4, 48, 54, 75–76

further study r equired, 108technique for the manufactur e & use of

capsules, 127

damage management, iv, 63deficiencies, 110estimation, 64history, 56implementation, 100–104

dasyurids, 64definition, x


effect of 1080 baits, 3Dasyurus geoffroii see chuditchdatabases, 103

ERIN, 90lack of benchmark data, 110

see also economic datadeficiencies in knowledge & appr oaches, 1,

72, 106–111dens, 83

den counts, 63, 70aerial survey techniques, 70need for mor e information, 106tarbaby technique, 76–77, 108

fumigation & destruction, 51, 76, 83, 92developments required, 108

density of foxes, 3, 15, 16–17, 34, 63, 69hunting ef fectiveness, 83hunting indicator of population density

(HIPD), 69need for further study, 26, 107population manipulation index, 70scent stations, 69spotlight counts, 69use of measur ements, 70–72see also den counts

Dept of Primary Industries and Ener gy, viiidiet of the fox, 2, 15, 24–25, 64diethylstilbestrol (DES), use in fertility contr ol, 85dingoes, 15

effect of bounties, 56–57effect of dingo fence, 16, 17effect on fox population, 15, 16effect on lambs, 39poisoning, 22use of soft catch traps, 53

diseases & parasites, 2, 15, 20–21distemper, 2, 15mange, 2, 15, 22role of foxes in spr ead of exotic diseases,

iiisee also rabies

dispersal see distributiondistribution, 12, 15–18

dispersal behaviour, 13, 15, 23–24, 94see also geographic infor mation systems

dogscontrol of wild dogs, 60fox predators, 15guard dogs, 85relationships to foxes, 11role in rabies, 43–44

use in fox hunting, 49, 50, 82see also dingoes

drought, effect on foxes, 2, 15, 21Dryandra State For est

ecotourism, 40–41fox control program, 33

ducklings, fox pr edation, 40dystocia, 40, 65

definition, x

Ecologically Sustainable Development strategy, 7ecologically sustainable land management, ivecology of foxes, 5lack of information, 109–110economy

economic & environmental impacts, 27–42, 48economic data, 89economic frameworks, 89economic value of wildlife conservation, 92framework for management, 3value of fox pelts, 27, 41

ecotourism, effect of fox pr edation, 27–28,40–41

electrified fencing see exclusion fencingemu farms, fox pr edation, 40Endangered Species Advisory Committee

(ESAC) Report, 28–29Endangered Species Pr ogram, 102Endangered Species Protection Act 1992, 58,

102, 110endangered species

definition, xextinctions, 28–30, 35government assistance, 89need for Threat Abatement Plan, 58predation by foxes, 1protection, ivsuggested studies, 65use of exclusion fencing, 84

endoparasite, 15, 18, 20definition, x

environment impact assessment, 64–65Environmental Impact Statements, 64Environmental Resource Information Network

(ERIN), 90environmental damage, iiienzootic areas, 2

definition, xeradication of foxes, 4

criteria, 132local eradication, 91


Eudyptula minor see penguins, little penguineuro, fox pr edation, 34European red fox, 1, 9, 11evaluation see monitoring & evaluationewes, ultrasound scanning, 2, 39, 67exclusion fencing, 58, 84–85

electrified fences, 84need for more information, 106

see also fox-proof fencingextinctions see endangered species

family group, 19, 23, 25, 69definition, x

farming practices, tool for fox contr ol, 72, 85fauna

damage by foxes, 1–2see also native species

see also non-target faunafencing, 92

see also exclusion fencingsee also fox-proof fence

Feral Pests Program, 102feral animals

ANZFAS attitude to curr ent management,93

catseffect of fox contr ol, 34,107effect on malleefowl, 33effect on numbats, 34effect on rabbits, 2effect on r eintroductions of native

species, 35variations in numbers, 20, 21

management by ANCA, 58pigs, 39, 64fertility control see reproduction

fleas, European rabbit flea, 37Flora and Fauna Guarantee Act 1988, 60, 110fox drives, 82, 102fox-proof fencing, 92, 108–09

see also exclusion fencingFoxlotto, 3, 60Foxoff baits, 59, 78

degradation, 78instructions for use of baits, 128–131use in Victoria, 60, 102

fumigation of dens, 51

geographic information systems (GIS), 63, 70,71, 104

definition, x

gestation, 15, 19, 81, 92definition, x

glossary, x–xigoals, lack of benchmark data, 110goats, fox pr edation, 40, 88governments

assistance for fox contr ol, 89, 101beneficiary pays principle, 101, 103Commonwealth management of vertebrate

pests, 7, 102deficiencies in administration pr ocedures,

110legislation & strategies, 5need for agency cooperation, 106

see also individual statesguidelines for fox management, iii

purpose, 1

habitatsmodification, 86–87mosaics caused by fir e regimes, 35use, 1 1, 15, 17–18, 25see also urban foxes

harvesting see commercial harvestinghistory of foxes in Australia, 1, 11–14home ranges, 15, 22–23

definition, xestimates, 22

human intervention, ef fect on foxes, 21humane techniques for contr ol of foxes

cyanide, 54definition, 50fumigation, 83humane use of snar es, 53inhumanity of chlor opicrin, 51shooting, 48, 50–51use of 1080, 4, 48use of leg-snar e devices & traps, 4, 52, 82

humane use of some traps, 52–53use of phosphine gas on rabbits, 52use of poisons, 4, 48view of ANZFAS, 49

Hunt Clubs Association of V ictoria, defence offox hunting, 50

hunting of foxes, iv, 4, 22, 38, 48–49, 82–85, 92defence by the Hunt Clubs Association of

Victoria, 50effectiveness, 83RSPCA attitude, 50

see also commercial harvestinghydatid parasite in foxes, 2


immunisation against rabies, 45, 86immunosterility, definition, x, 4–5impact assessment, 64–67

impact on animals other than mammals,107

use of impact measur ements, 70–72information transfer, 105interest groups, attitudes, 1International Wool Secretariat, viiiisland refuges, 85

jackals, 11, 19

Lagorchestes hirsutus see wallabies, rufoushare-wallabies

lambsbirth process, 38causes of lamb loss, 63, 65–67cost of fox contr ol, 93fox shoots with r educed lamb losses, 49prey for the fox, 1, 2, 27, 37, 38–39

quantification, 5, 40, 67rogue foxes, 39use of ultrasound scanning on ewes, 2Land and Water Research and Development

Corporation, viiiland managers

adaptive management, 91assessment of lamb pr edation by foxes, 67awareness of exotic disease risk, 47case studies, 90economic frameworks, 89holistic approach, 7information on fox contr ol, 1need for further study, 5, 26primary aim, 7strategic approach to foxes, 3–4use of computerised GIS, 104

LandCare, 102use of maps, 103–104

Landcareholistic approach, 7involvement in fox contr ol, 1, 5, 71, 101regional coordination, 104

landholders’ responsibilities, 57–58, 101, 103assistance with & use of maps, 70, 104by state

ACT, 59NSW, 61NT, 58Qld, 59

SA, 61Tas, 62Vic, 60WA, 59

time required for hunting, 81LD

50, 53, 54, 74definition, x

legislationdeficiencies, 110–11legislative provisions for foxes, 58–60, 101requirements for fox poisoning, 75use of soft-catch traps, 83

Leipoa ocellata see malleefowllivestock

commodity prices, 55fox prey, 1, 2, 38

assessment, 67Vertebrate Pest Program, 40

local & community involvement seecommunity-based schemes

local or r egional approach to management, 4,88–100

examples of strategic management, 95–100macropods & fox management, 5

definition, xMacropus eugenii see wallabies, tammar

wallabyMacropus robustus see euroMacrous parma see wallabies, Par ma wallabiesmaintenance control, 91malleefowl, 28, 33mammals, survey techniques, 64management of foxes, iii–iv, 3, 63

advisory service, 101assessment of achieved objectives, 94buffer zones, 102case studies, 1coordinated management on public land, 60crisis management, 92deficiencies, 1, 71, 106–111history, 56implementation of fox damage

management, 101–105integrated management, 85legislative provisions, 58management programs see individual

programsorganisation, 110past & current management, 56–63precautionary management, 5, 88, 92

see also community-based schemes


see also strategic managementsee also under individual states

management plans, 4, 7–8crisis management, 4implementation, 4, 8–9local & regional levels, 4, 8, 88management options, 90–92objectives, 90performance indicators, 93–94

see also best practicesee also monitoring & evaluation

management strategy see strategic managementmanagement units

priorities for treatment, 72use of maps, 72

Managing Vertebrate Pests: Principles andStrategies, iv, 7

maps & mapping, 70–71, 93community use, 103–104

marsupials, predator removal experiments,29–33

Meat Research Corporation, viiimice, chloropicrin fumigation, 51Ministry of Agriculture, Fisheries and Food

(MAFF) UK, baiting systems, 46monitoring & evaluation of pr ograms, 4, 9

88–89, 94–95fox density, 63measurement techniques, 63–87operational monitoring, 4, 94performance indicators, 93–94performance monitoring, 4, 94–95PMIS, 94prey density, 63steps for monitoring pr ograms, 95

see also impact assessmentMurray Darling Basin Commission, viiiMus domesticus see miceMyrmecobius fasciatus see numbatmyxomatosis see rabbits

National Consultative Committee on AnimalWelfare

ban on strychnine use, 54conclusions on exclusion fencing, 84consultation, iii, viii

National Farmers’ Federation, consultation, iii,viii

National Landcare Program, 7see also Landcare

National Parks and Wildlife Act 1970, 62

National Strategy for the Conservation ofAustralia’s Biological Diversity, 7

native speciescompetition by foxes, 36development of Action Plan, 60–61diet studies of the fox, 25display in fox-pr oof enclosures, 40effect of foxes on ecotourism, 27–28effects of fox contr ol in WA, iii, 1, 27factors other than foxes causing decline,

64–65government assistance, 101habitat modification outcomes, 87increases in pr edation pressure, 2, 28–30increasing concern, 22lack of infor mation on the fox as a

competitor, 109need for quantification, 5, 25, 29, 64reintroduction attempts, 35role of fox & rabbit contr ol, 27, 35use in impact assessment of foxes, 64

Nature Conservation Act 1980, 59neophobia, 108

definition, xiNew Zealand, pest contr ol processes, 110nocturnal, definition, xinon-target fauna

aerial baiting, 79dangers of fr ee feeding, 81effect of fences, 84need for further investigation, 80use of poisons, 58, 73, 77–78, 80use of snar es, 82–83use of traps, 82

Northern Land Council, consultation, iii, viiiNorthern Territory, Conservation Commission

of the Norther n Territory, 58numbats

effects of foxes, iii, 32–33, 34population recovery, 41

numbers of foxes see abundance of foxes

ostrich farms, fox predation, 40

parasites see diseases & parasitesparturition, definition, xipelts

anti-fur lobby, 41definition, xi,value of fox pelts, 27, 41

effect on fox damage, 54


penguins, 60little penguin, 41

perceptions of the fox, iii, 48performance monitoring see monitoring &

evaluationPest Monitoring Infor mation Systems (PMIS), 94pest control, quantification of, iii–ivpest management

New Zealand, 110training, 110

Petrogale lateralis see wallabies, rock-wallabiesPetrogale penicillata see wallabies, brush-tailed

rock-wallabyPetrogale rothschildi, see wallabies, rock-

wallabiesphosphine gas

den destruction, 83use on rabbits, 52

poisoning of foxes, 1, 4, 22, 40, 53–54, 74–82arid regions, 35–36contract poisoning in WA, 59costs of fox contr ol, 40cyanide, 4, 48, 54, 76–77, 108home range sizes, 23need for mor e information, 106non-target fauna, 58regulation by legislation, 58, 76RSPCA attitude, 50strychnine, 46, 48, 74, 77susceptibility to secondary poisoning, 37timing of poison use, 82

see also 1080see also baitssee also den fumigation

pollution, ef fect on ecotourism, 41population size, 68possums, 64

effect of fox contr ol programs, 32brushtail possums, 32, 33, 41western ringtail possum, 86–87

potoroos, viewing by the public, 40poultry, fox pr edation, 2, 39–40predation by foxes, iii

effect of rabbit densities, 36need for further study, 107need for quantification, 5predator removal experiments, 29–35

see also under individual animalspredators, 21

Codes of Practice, 50mutilation of lambs, 38

Pseudocheirus occidentalis see possums,western ringtail possum

publicity & public r elations, 105, 109Puffinus tenuirostris see short-tailed shearwaterpurpose of the guidelines, 1

Queensland, Dept of Lands, Land Pr otectionBranch, 59–60

quollseastern quoll, 36effect of 1080 baits, 3western quoll, 36

rabbitseffect of feral cats, 2effect of foxes on numbers, 2, 14, 22, 27, 36effect of numbers on foxes, 2, 3, 13–14, 85effect of predators, 20effects of chlor opicrin fumigation, 51myxomatosis, 2need for further study, 107need for quantification of fox/rabbit

relationship, 5role of fox in rabbit contr ol, 2, 27use of burr ows by the fox, 19

rabies, 15, 20, 22, 43–47AUSVETPLAN, 47control methods, 45dispersal studies, 24immunisation, 45population reduction, 47role of foxes in spr ead of the disease, iii, 2, 44simulated outbreaks, 47use of HIPD to calculate thr eshold

densities for transmission, 68vaccination of foxes, 44–47

range expansion consequences, 36RD

50

definition, ximeasurement after fumigation of mice

with chloropicrin, 51recolonisation of foxes, 3, 4, 79, 81, 82, 93recombinant virus, 46, 86

definition, xirecreational hunting see huntingreferences, 112–25reinvasion see recolonisationrelict population, definition, xireproduction in the fox, 2, 15 , 19–20

abortion-inducing hormones, 85anti-fertility agents, 85–86


gassing of breeding dens, 3litter size, 19sterilisation, 86

reptileseffect of fox pr edation, iii, 5survey techniques, 64

road kills, 21rodents, 64 see also miceRSPCA Australia

attitude to hunting, 50attitude to leg-hold snar e trap, 53, 82

Rural Industries Research and DevelopmentCorporation, viii

Rural Lands Protection Act 1985, 59

scat, 64, 90, 130definition, xi

secondary poisoning, 22, 37, 97, 130definition, xi

sheep industry, 18role of the fox, 39

shooting of foxes, 3, 21, 48, 49, 50–51, 81–82community involvement, 59, 81–82

short-tailed shearwater, fox predation, 34snares see trapssocial organisation, 25sodium monofluoracetate see 1080spotlight traverse, 30, 32

definition, xiStanding Committee on Agricultur e and

Resource Management (SCARM), iii, viii, 7Sub-committee on Animal Welfare, Codes

of Practice, 50States Cooperative Assistance Pr ogram, 102states see landholders’ r esponsibilities

see also individual programsstrategic management, iv, 3, 91, 92

attitudes affecting fox management, 48–55commercial harvesting, 57–58economic frameworks, 89impact on native fauna of management

programs, 34implementation, 88, 94key components, 4local and regional level, 88–100

hypothetical examples, 95–98management plan, 90–94national management, 8problem definition, 89strategic approach, 89

see also monitoring and evaluation

strychnine, 46, 48, 54summary, 1–5survey methods for faunal gr oups, 64–65

tarbabydefinition, xi

techniques, 76–77, 108Tasmania, Dept of Envir onment and Land

Management, 62Dept of Primary Industry and Fisheries, 62Tasmanian devil, 36Territory Parks and Wildlife Conservation Act

1988, 58tetanic spasms, definition, xiThreat Abatement Plan, 110impact of foxes, 58threatened species see endangered speciesTidbinbilla Nature Reserveroutine fox management, 59tortoise species, fox pr edation of eggs, 34tourist industry see ecotourismtraining in pest management, 110transect, definition, xitranslocation, definition, xitraps, 3, 4, 21, 45, 52–53, 82–83

snares, 82–83steel-jawed traps, 82

Trichosurus vulpecula see possums, brushtailpossums

turtles, effect of foxes, 60

ultrasound scanning, 67definition, xi

see also ewesurban foxes, 16

causes of deaths, 21–22further study r equired into baits, 108habitats, 17–18Queensland, 60territories, 22, 23use of snar es, 53, 81

vaccination of foxes see rabiesvectors, definition, xiVermin Destruction Act 1950, 62Vertebrate Pest Pr ogram (VPP), iii, 1, 9, 102Vertebrate Pests Committee, Strategic

Vertebrate Pest Working Grouprecommended dose rate for 1080, 75role in the guidelines, viii, 1

Victoria, Dept of Conservation and NaturalResources (DCNR), 60–61, 102


vulnerable speciesdefinition, xi

see also endangered speciesVulpes vulpes, 1, 9, 11wallabies, 64

decline of the brushtailed r ock-wallaby,28

Parma wallabies, 35rock-wallabies

black-footed rock-wallaby, 1effects of foxes, iii, 1predator removal experiments, 29–32yellow-footed rock-wallabies, 34

rufous hare-wallabies, 35tammar wallaby, ef fect of fox contr ol

program, 32, 33viewing by the public, 40

Western Australia, Agricultur e ProtectionBoard (APB), 58–59

Western Australia, Dept of Conservation andLand Management

cooperative research programs, 106–107fox control programs, 59, 63

whole property planning, 7–8wildlife conservation, 71

see also native specieswolves, relationship to foxes, 11, 16, 19


Managing Vertebrate Pests: Foxes - PestSmart

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