DIETS OF FREE-RANGING MEXICAN GRAY WOLVES IN ARIZONA AND NEW MEXICO by JANET E. REED. B.S. A THESIS IN WILDLIFE SCIENCE Submitted to the Graduate Faculty of Texas Tech University in Partial Fulfillment of the Requirements for the Degree of MASTER OF SCIENCE Approved Chairperson of the Committee Accepjpd Dean of the Graduate School May, 2004
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DIETS OF FREE-RANGING MEXICAN GRAY WOLVES
IN ARIZONA AND NEW MEXICO
by
JANET E. REED. B.S.
A THESIS
IN
WILDLIFE SCIENCE
Submitted to the Graduate Faculty
of Texas Tech University in Partial Fulfillment of the Requirements for
the Degree of
MASTER OF SCIENCE
Approved
Chairperson of the Committee
Accepjpd
Dean of the Graduate School
May, 2004
ACKNOWLEDGEMENTS
I thank the United States Fish and Wildlife Service (USFWS) for fiinding this
project I appreciated the direction of Mexican wolf recovery leader and committee
member, Brian T Kelly, the assistance of Mexican wolf Interagency Field Team
personnel (i e , USFWS, Arizona Game and Fish Department, New Mexico Department
of Game and Fish, USD A APHIS Wildlife Services, and US Forest Service [USFS])
and all the volunteers who coUected scats Thank you, David R Parsons and Wendy
Brown, for mentoring and believing in me
I thank Dr Warren B Ballard, my major advisor, for providing encouragement
and guidance throughout this study Special thanks go to committee member Dr Robert
J Baker for welcoming me into his genetics lab and to Celine C Perchellet, Adam
Brown, and Drs Jeff Wickliffe and Federico Hoffman for their dedication, assistance,
and humor in the DNA lab I also thank committee members Drs Philip S Gipson, Paul
R. Krausman, and Mark C Wallace for their ad\ice and support A special thank you to
Dr David B Wester for facilitating the statistical analyses
I thank the USFS Alpine and Clifton Ranger Districts for their assistance on the
forest A special thank you to Myron C Burnett, USFS Wilderness Ranger, for rising
above the opposition to teach me to pack burros and believing that I could handle the job
I also thank the residents of Alpine for welcoming me into their community and all the
forest visitors who assisted with scat collecting Thank you Waypoint Enterprises, Show
Low, Arizona, for your donation of UTM and Multi Waypointers
My parents, Roger C and Betty A Stone, my sister, Anita D. Moore, and my
fnend, Alan B Alley, provided unwavering support and encouragement throughout my
education. Thanks to my two burros, Pancho and Lefty, who carried my gear and the
stinky carnivore scats tirelessly over many miles. Finally, my dog. Kaiser von
Stockwerk, provided faithfiil companionship for MVJ years His unconditional love was
greatiy appreciated
111
TABLE OF CONTENTS
ACKNOWLEDGEMENTS ii
ABSTRACT vi
UST OF TABLES viii
USTOFnOURES x
CHAPTER
I INTRODUCTION 1
Literature Cited 2
n fflSTORICAL OVERVIEW OF THE MEXICAN GRAY WOLF
AND ITS RECOVERY 3
Literature Cited 7
in DIFFERENTIATING MEXICAN WOLF AND COYOTE SCATS
USING DNA ANALYSIS 10
Abstract 10
Introduction 11
Study Area 12
Materials and Methods 14
Results 22
Discussion 24
Acknowledgements 31
Literature Cited 32
IV
IV. DIETS OF FREE-RANGING MEXICAN GRAY WOLVES IN
ARIZONA AND NEW MEXICO 45
Abstract 45
Introduction 47
Study Area 48
Methods 51
Resuhs 55
Discussion 57
Acknowledgements 64
Literamre Cited 65
V SUMMARY 82
ABSTRACT
The Mexican gray wolf (Catiis lupus baileyi) was extirpated from the
southwestern United States before any systematic smdies could be conducted, therefore
littie is known about the subspecies' natural history From April 1998 through October
2001, we coUected carnivore scats {n = 1,682) from the Blue Range Wolf Recovery Area
(BRWRA) in .\rizona and New Mexico to study the diets of free-ranging Mexican
wolves We identified the scats to species using traditional field methods (i e , diameter,
location, and sign) and odor, but expected that it would be difficult to separate Mexican
wolf and sympatric coyote {Cams latrans) scats We tested this hypothesis whh fecal
DNA analysis (molecular scatology) to verify the accuracy of identifying Mexican wolf
and sympatric coyote scats Our DNA results showed scats > 28 mm diameter could be
identified as deposited by Mexican wolves, a high overlap in scat diameters for Mexican
wolves and sympatric coyotes, and a difference in the 2 species' scat diameter means
To determine the diets of Mexican wolves, we used our DNA results to refine our
scat identification criteria Scats for diet analysis were identified as deposited by
Mexican wolves by DNA analysis, diameters ^ 28 mm, 2 den site locations, and ttacks.
Diet analysis of 55 scats with diameters ^ 28 mm collected from areas where 6 Mexican
wolf packs received supplemental food items indicated Cienega and Hawks Nest packs
consumed non-supplemental food items during supplemental feeding and Campbell Blue,
Lupine, Mule, and Pipestem packs did not Diet analysis of 251 scats revealed non-
{Cerws elaphus caiKhJensis [nelsoni]) adults and calves We compared this diet
composition to that found in 26 scats identified with DNA analysis and found more large-
sized food items appeared in Mexican wolf scats identified by our refined traditional
method than in scats identified with DNA analysis There was no difference between
diameter means or number of food items per scat between the 2 scat identification
methods There was a difference between diet composition for 26 Mexican wolf scats
and that found in 21 sympatric coyote scats identified with DNA analysis, with Mexican
wolves consuming more large-sized food items than sympatric coyotes. There was also a
difference between diameter means and number of food items per scat for the 2 species,
vsith sympatric coyote scats containing more food items per scat than Mexican wolf scats.
Lastly, we found a difference in diet composition of Vtexican wolves when compared to
diet composition reported in 7 previous diet studies of other North American gray
wolves Mexican wolf diet analysis revealed more large-sized food items than the
subspecies' larger, northern counterparts
vn
UST OF TABLES
3.1 Comparison of accuracy of predicting which species (Mexican wolf or coyote) deposited a scat using discriminant analysis based on combination of 3 measurements takoi from scats identified to species with DNA analysis 43
3.2 Locations of scats (n = 47) identified as Mexican wolf or coyote with DNA analysis 44
4.1 Food items found in scats (n = SS) ^ 28 mm diameter collected from areas where Mexican gray wolf packs (n = 6) were fed supplemental food items (i.e., carnivore logs and road-killed elk, deer and jackrabbit) 71
4.2 ConqMurison of diet composition found in scats (n = 55) ^ 28 mm diameter from areas where Mexican gray wolf packs (n = 6) were fed supplemental food items (i.e., carnivore logs and road-killed elk, deer, and jackrabbit) to determine presence of non-supplemental food items (e.g., elk aduhs and calves, deo* adults and £Eiwns, domestic bovine, and insects) 72
4.3 Food items (n = 265) found in free-ranging Mexican gray wolf scats (/i = 251) 73
4.4 Comparison among years (n = 4,1998-2001) of diet composition found in scats {n = 251) of free-ranging Mexican gray wolves collected from April 1998 to October 2001 in Arizona and New Mexico 74
4.5 Comparison between seasons (n = 2, fiill-winter versus s|Hing-summer) of diet composition found in scats (/i = 251) of free-ranging Mexican gray wolves in Arizona and New Mexico (April 1998 - October 2001) 75
4.6 Comparison of diet conq)08ition among packs (n = 4) found in free-ranging Mexican wolf scats (n = 251) collected from AJptii 1998 to October 2001 in Arizona and New Mexico 76
4.7 Food items (n = 33) found in free-ranging Mexican gray wolf scats (n = 26) collected from April 1998 to October 2001 in Arizona and New Mexico 77
4.8 Comparison of diet c<Hiq)Osition of Mexican wolf scats (n = 277) collected from April 1998 to Oct(A>er 2001 in Arizona and New Mexico and identified u«ng 2 methods: DNA analysis (n = 26) and refined traditional (/t = 251; i.e., ^ 28 mm diameter, 2 den sites, and tracks) 78
4.9 Coiiq>ari8(ni of diet composition found in free-ranging Mexican wolf scats (/f = 26) and sympatric coyote scats (/i = 21) collected from hipdX 1998 to October 2001 in Arizona and New Mexico 79
viu
4.10 Food items found in free-ranging Mexican gray wolf scats (n = 26) and sympatric coyote scats (n = 21) coUected from April 1998 to October 2001 in Arizona and New Mexico 80
4. U ConqpariscHi of diet composition found in free-ranging Mexican wolf scats (n = 277) and diet oompositi(» reported in other North American gray wolf diet studies (n = 7) 81
IX
LIST OF FIGURES
2.1 The Bhie Range Wolf Recovery Area (BRWRA) in Arizona and New Mexico where Mexican gray wolves were released beginning April 1998 9
3 1 Agarose gd showing a portion of the mtDN A control region (D-loop) amplified via Pilgrim et al. (1998) canid-specific primers (Mexican wolf and dog, 164 bp; coyote 160 bp) 40
3 2 Agarose gel showing restriction fragment digestion with BstN I of mtDNA control r^on (D-loop) purified polym«-ase chain reaction (PPCR) isolated from Mexican wolf and coyote scats 41
3.3 Comparison of diameters of coyote scats (n = 21, range 17.4 to 27.8 m; X = 22.8 nun) and Mexican wolf scats (n = 26; range 16.3 to 35.8 nun, x = 26.0 nun) identified with fecal DNA analysis 42
CHAPTER I
INTRODUCTION
The following chapters constitute partial fulfillment of the requirements for the
degree of Master of Science in Wildlife Science for the Graduate School at Texas Tech
University These chapters are the resuh of research conducted on Mexican gray wolves
(Cojus lupus baileyi) m Arizona and New Mexico from April 1998 through October
2001 Chapter II is an historical overview of the Mexican gray wolf and its recovery
Chapters ID and I\' are 2 manuscripts intended for submission to peer-reviewed journals.
Chapter III discusses differentiating Mexican wolf and coyote scats using fecal DNA
analysis (molecular scatology) Chapter IV reports the diets of free-ranging Mexican
wolves in .\rizona and New Mexico from April 1998 through October 2001, and
compares the diets of Mexican wolves to sympatric coyotes and to other North American
gray wolves Chapter V is a summary of all chapters ,\11 chapters represent my ideas,
analyses, and writing ability Each chapter has several coauthors, which were determined
using guidelines provided by Dickson and Conner (1978) and the CBE Style Manual
Committee (1994) .Authorships for chapters are as follows
Chapter III Janet E Reed, Robert J Baker, Warren B Ballard, and Brian T Kelly
Chapter IV; Janet E Reed, Warren B Ballard, Philip S Gipson, Brian T Kelly, Paul
R Krausman, Mark C Wallace, and David B Wester
LiteraUire Cited
CBE Style Manual Committee 1994 Scientific style and format: the CBE manual for authors, editors, and publishers Sixth Edition Council of Biology Editors, Cambridge University Press, New York, New York, USA.
Dickson, J. G., and R N Conner 1978 Guidelines for authorship of scientific articles. Wildlife Society Bulletin 6: 260-261
CHAPTER II
HISTORICAL OVERVIEW
OF THE MEXICAN GRAY WOLF AND ITS RECOVERY
Historically, the Mexican gray wolf (Ca7>/5 lupus baileyi), or lobo, lived the
farthest south of all gray wolves (C lupus) on North America and in the most arid
environment at elevations from 1,200 to 3,300 m ranging throughout central and
southeastern Arizona, western Texas, southern New Mexico, and most of Old Mexico
(Young and Goldman 1944, Brown 1983, Parsons 1996) h is believed that the Mexican
wolf comributed to the overall historical biological diversity and ecological functioning
of both the southwestern ecosystems and the continued evolution of species the Mexican
wolf preyed upon (Parsons 1998)
It is uncertain if the Mexican wolf was sympatric with the coyote {Canis latrans)
in the Southwest before humans altered its natural habitat (Brown 1983) Gier (1975)
and Bekoff and Wells (1986) reported that historical coyote distnbutions were confined
primarily to plains and deserts until the spread of civilization and the reduction of gray
wolf ranges
By the early 1880s, humans and associated livestock had moved into the
Southwest in large numbers (Brown 1983, Shumway 1998) Due to overgrazing and
unregulated subsistence and market hunting, native prey species were in decline and
some predators turned to the more abundant and easily caught livestock (United States
Fish and Wildlife Service 1987) Government and private predator comrol programs
designed to protect livestock in the United States and Mexico accelerated the extirpation
of the Mexican wolf from the Southwest by the late 1960s (Gipson and Ballard 1998).
In 1975, the Arizona-Sonora Desert Museum proposed to capture Mexican
wolves from the remaining population in Mexico and to place them in a captive-breeding
program for future re-estabhshment of the subspecies in its historic range (Siminski
1997) The United States government listed the Mexican wolf as endangered in 1976 and
Mexico began protecting this subspecies, as well (United States Fish and Wildlife Service
1996) The last 4 Mexican wolves known to exist were captured in Durango and
Chihuahua, Mexico from 1977 to 1980 (McBride 1978) and 3 of them founded an official
captive-breeding program (Garcia-Moreno et al 1996, Hedrick et al 1997) To increase
genetic diversity in the official Certified (renamed McBride) lineage, 2 other captive
Mexican wolf populations, Arag6n and Ghost Ranch lineages, were certified genetically
pure in July 1995 (Hedrick et al 1997) and incorporated into the official captive-breeding
program The first offspring from cross-lineage pairings were produced in 1997 (Parsons
1998) .\s of October 2001, the global population of Mexican wolves consisted of 227
individuals, the majority of which were held in 40 zoos and wildlife sanctuaries
throughout the United Stales and Mexico (P Suninski, Arizona-Sonora Desert Museum,
personal communication)
Recovery efforts for the Mexican wolf were outlined in the Mexican Wolf
Recovery Plan (United States Fish and Wildlife Service 1982) and research flinded by the
Lmted States Fish and Wildlife Service (USFWS) supported experimental releases of
Mexican wolves imo isolated Southwest habitat where close monitoring could be
conducted (Bednarz 1988) The Final Envu-onmental Impact Statement (FEIS) for the
Mexican wolf proposed reintroduction of the subspecies into a portion of its historical
range in Arizona, New Mexico, and Texas (United States Fish and Wildlife Service
1996) Three areas were considered the Blue Range Wolf Recovery Area (BRWRA) in
.\rizona and New Mexico, White Sands Missile Range Wolf Recovery Area in New
Mexico, and Big Bend National Park in Texas This proposal was formally approved by
Secretar, of the Interior Bmce Babbitt's March 1997 Record of Decision (United States
Fish and Wildlife Service 1997). In April 1998, the first 11 captive-reared Mexican
wol\ es-5 generations removed from the wild-were released within the primary recovery
zone of the BRWRA on the Apache National Forest in east-central Arizona (Figure 2 1).
In the spring 2000, Mexican wolves previously released in Arizona were translocated to
the secondary recovery zone on the Gila National Forest and Wilderness in New Mexico
As of October 2001, at least 37 Mexican wolves were resident within the BRWTIA and
31 of those were radiocollared (United States Fish and Wildlife Service, unpublished
data)
In June 2000, we began a study to determine the diets of free-ranging Mexican
gray wolves in Arizona and New Mexico We collected 1,682 carnivore scats from April
1998 through October 2001 and identified them to species using traditional identification
methods and odor We verified scat identification accuracy with fecal DNA analysis
(molecular scatology) and refined our identification of Mexican wolf scats We then
analyzed Mexican wolf scats identified with DNA analysis and our refined traditional
identification method to determine the diet composition of free-ranging Mexican wolves
in Arizona and New Mexico
Literature Cited
Bednarz,! C 1988 The Mexican wolf biology, history, and prospects for reestabhshment in New Mexico Endangered species report No. 18 United States Fish and Wildlife Service, Albuquerque, New Mexico, USA.
Bekoff, M . and M C Wells 1986 Social ecology and behavior of coyotes Advances in tiie Stiidy of Behavior 16: 251-338
Brown, D E 1983 The wolf in the Southwest: the making of an endangered species. The University of .\rizona Press, Tucson, Arizona, USA
Garcia-Moreno, J , M D Matocq, M S Roy, E Geffen, and R K Wayne 1996 Relationships and genetic purity of the endangered Mexican wolf based on analysis of microsatellite loci Conservation Biology 10 376-389
Gier. H T 1975 Ecology and behavior of the coyotes (Co^iw/a/rans), pages 247-262/>/ M W Fox, editor The Wild Canids their systematics, behavioral ecology and evolution Van Nostrand Reinhold, New York, USA
Gipson, P S , and W B Ballard 1998 Accountsof famous North American wolves Canadian Field-Naturalist 112 724-739
Hednck, P W , P S Miller, E Geffen, and R K Wayne 1997 Genetic evaluation of the three captive Mexican wolf lineages Zoo Biology 16 47-69
McBride, R T 1978 Statusof the gray wolf (ran/5/M^.vZ)a//ev/) in Mexico United States Fish and Wildlife Service Report, Albuquerque, New Mexico, USA.
Parsons, D R 1996 Case Smdy the Mexican wolf Pages 101-123 inE A. Herrera and L F Huenneke, editors New Mexico's natural heritage biological diversity in the Land of Enchantment New Mexico Journal of Science 36 101-123
Parsons, D R. 1998 "Green fire" returns to the Southwest reintroduaion of the Mexican wolf Wildlife Society Bulletin 26: 799-807
Shumway, E W 1998 Alpine, Arizona a stroll through history, Americopy, Mesa, Arizona, USA
Simmski, D P 1997 A history of cooperation in Mexican wolf conservation Proceedings American Zoo and Aquarium Association Regional Conference 1997 384-385
United States Fish and Wildlife Service. 1982. Mexicanwolf recovery plan. United States Fish and Wildlife Service, Albuquerque, New Mexico, USA
United States Fish and Wildlife Service 1987. Restoring America's wildlife 1937-1987: the first 50 years of the Federal Aid in Wildlife Restoration (Pitman-Robertson .\ct) Unhed States Department of the Interior, United States Fish and Wildlife Service, Washington, D C , USA.
United States Fish and Wildlife Service 1996 Reintroduction of the Mexican wolf within its historic range in the southwestern United States Final Environmental Impact Statement. United States Fish and Wildlife Service, Albuquerque, New Mexico, US.\
United States Fish and Wildlife Service 1997. Record of decision and statement of fmdings on the environmental impact statement on reintroduction of the Mexican gray wolf to rts historic range in the southwestern United States United States Fish and Wildlife Service, Albuquerque, New Mexico, USA
Young, S P . andE A Goldman 1944 The wolves of North America The American Wildlife Institute, Washington, D C , USA
CHAPTER III
DIFFERENT1.\TING MEXICAN GRAY WOLF AND
COYOTE SCATS USING DNA ANALYSIS
Abstract
We used fecal DNA analysis (molecular scatology) to test a subsample of scats
(// = 203) identified as deposited by Mexican gray wolves (Ca j/5 lupus baileyi) or
coyotes {Cams latrans) and compared the resuhs to the identification of scats using
traditional methods (i e , diameter, location, and sign) and odor We then used the scats
identified with DN.A. analysis to evaluate discriminant analysis for classifying scats using
3 measurements (i e , diameter, mass, and length) Forty-nine (24° o) of the field-
accuratdy identified 81% of coyote scats, but only 50% of Mexican wolf scats Scat
diameter and mass (Classification 2) accurately identified 86% of coyote scats and 65%
of Mexican wolf scats Scat diameter and length (Classification 3) accurately identified
68% of coyote scats and 59% of Mexican wolf scats Lastly, a combination of scat
diameter, mass, and length (Classification 4) accurately identified 79% of coyote scats
and 55% of Mexican wolf scats
Discussion
Fecal material is often the most common sign and easily collected source of
information for rare, secretive carnivores (Putman 1984), and scat analysis appears to
provide the best noninvasive sampling method for determining diets of free-ranging
carnivore species However, which species actually deposited a scat must be accurately
determined for the method to be vahd Traditional scat identification criteria have been
based primarily on morphology (Halfpenny 1986, Foran et al 1997), which can be
subjective and confounded by sympatric species that are comparably sized and share
similar diets (Weaver and Fritts 1979, Green and Flinders 1981, Danner and Dodd 1982,
24
Foran et al 1997). Halfpenny (1986) reported that visual identification of scat to species
by experienced naturaUsts had error rates approaching 50 to 66%. Scott (1941, 1943)
reported tiiat fecal passage sizes varied approximately in proportion to the amount of
food consumed Weaver and Fritts (1979) reported tiiat scat diameter might be
influenced by diet composition and suggested that canid scats could not be identified to
species based on diameter alone Previous dietary analysis based on scat identification
using diameter alone may have biased results in favor of prey items that produce larger
scat diameters (Danner and Dodd 1982)
Halfjpenny (1986) reported that scat diameter and length values do not provide
positive identification of a species, because both values are too variable to be used as
adequate diagnostic criteria Green and Flinders (1981) reported that the dry mass of
scats \aried considerably for coyotes and red foxes and suggested that diameter used in
conjunction with mass could be used for identifying scats of the 2 species Discriminant
analysis of diameter and mass values of scats (Classification 2) provided the most
accurate identification for both species (coyote, 86%, Mexican wolf, 65%) However,
14°'o of the scats deposited by coyotes were classified incorrectly as Mexican wolf scats
and 35° 0 of the Mexican wolf scats were classified incorrectly as coyote scats Although
diameter and mass values provided a relatively high percentage of accuracy for
identifying coyote scats, we considered the resuhs unsatisfactory for identifying Mexican
wolf scats
Uncollectible scats, as defined by Floyd et al (1978), have traditionally been
discarded because it is difficult to identify them to species and uncollectibles usually
25
contain little identifiable prey material We were able to isolate DNA and identify the
species of 2 uncollectibles subsampled When using the appropriate primers, it is also
possible to amplify any prey DNA found in uncollectibles so that they can now be
included in cami\ore diet studies, if desired
Location of where scats have been deposited has also been used to identify wolf
scats for diet analysis smdies Scats collected from wolf den and rendezvous sites
undoubtedK have provided accurate diet information because coyotes rarely attend these
areas (Ballard et al 2003) However, the information only provides wolf diet data for
late spring through summer (Murie 1944, Mech 1966, Ballard et al 1987, Fuller 1989,
Spaulding et al 1997) Identification of scats collected from kill and carcass sites
(Thompson 1952, .Arjo et al 2(X)2) may be more problematic in areas where wolves and
coyotes are svmpatric because coyotes often scavenge from wolf kills (Paquet 1992,
Phillips and Smith 1996) The scats (n = 47, Table 3 2) from which we were able to
isolate DN.A were collected from forest trails (21 scats), forest highways, roads, and
2-tracks (16 scats), an elk carcass (1 scat), a wolf den (1 scat), an opened release pen
(2 scats), and other locations (i e , stream bed, cabin area, crater, canyon, mesa, and ridge,
6 scats)
Odor has also been reported as a scat identification technique, but it is subjective
(Stokes and Stokes 1986, Bang 2001) and currently cannot be quantified The only
mention of odor in the literature as an identification technique was for fox (Scott 1943,
Murie 1954, Wilcomb 1956, Korschgen 1980, Turkowski 1980), not for wolves or
coyotes Halfpenny (1986) suggested that odor resuhed from the camivore's diet
26
However, some wolf biologists have reported through personal communications that they
can identify wolf scats by odor, but tiiis claim has not been scientifically substantiated
and our resuhs suggest that odor was not a reliable method for this stiidy
Another attempt to identify carnivore scats has employed bile acids (Eneroth and
Sjovall 1969, .Alfred 1980, Major et al 1980, Clinite 1981, Johnson et al 1984, Quinn
and Jackman 1994) or pH (Green and Fhnders 1981) with httle or no success According
to Halfpenny (1986), these methods have proven more successful for herbivores than
carnivores
Recent noninvasive sampling studies of free-ranging mammals (Foran et al 1997,
Kohn and W ayne 1997, Reed et al 1997, Ernest et al 2000, Lucchini et al 2002) have
confirmed that fecal DNA analysis provides a more accurate assignment of the species
that deposited a scat rather than morphology of scats With noninvasive sampling and
fecal DN.A analysis, biologists can collect individual fecal samples at any time, from any
location, to study free-ranging species without having to disturb them (Hoss et al 1992,
Taberlet and Bouvet 1992. Morin et al 1993, Kohn and Wayne 1997, Taberlet et al
1999) We were able to collect scats from the field and isolate DNA for species
identification without ever seeing or dismpting the individuals
DNA from sloughed intestinal epithelial cells found on fecal material provides an
objective marker for species identification, and potentially for individuals, that remains
invariable during the life of an animal (Foran et al 1997) Mitochondrial DNA is
inherited maternally and is non-recombining (Brown 1985), making it well suited for
species identification of fecal samples (Moritz 1994, Kohn and Wayne 1997) and
27
mammalian population genetic stiidies (Randi et al. 1994, Slade et al. 1994, Taberlet et
al 1995) Mitochondrial DNA's extia-nuclear genome provides several hundred copies
per cell (Kohn et al 1995) and is more amenable to genetic manipulation than single-
copy nuclear genes (Kohn and Wayne 1997, Frantten et al 1998). The control region
(D-loop) is usually more polymorphic and informative for differentiating species (Pilgrim
et al 1998) because it evolves faster in mammals than either the rest of the mtDNA
molecule or most single-copy nuclear DNA (Avise 1994) Beginning with small
quantities of relatively short target sequences of DNA (Walsh et al. 1991. Mullis et al
1994. Reed et al 1997), the PCR is an enzymatic process that can experimentally
synthesize a large number of copies of specific DNA sequences from degraded or impure
samples (Saiki et al 1985, Mullis and Faloona 1987, Saiki et al 1988, Amheim et al
1990, Walsh et al 1991) When applied to mtDNA sequences useful for estimating
genetic differences between closely related species can be amplified (Kocher et al 1989,
.A\ise 1994) Species identification of scats using DN.A-based assays provides an
accurate method that is rapid (3-4 days), repeatable, and relatively inexpensive (The cost
is approximately $5 00 [USJ/sample for the disposable items, enzymes, and chemicals
required for sequencing Other costs include the sequencer, non-disposable lab
equipmem [e g , pipetors, cameras, and computers] and salaries of students and
technicians ) Furthermore, the resuhs are definitive and not subject to confidence
intervals or probabilistic estimation (Foran et al 1997) However, our low DNA isolation
success (24%) may be cause for concem
28
DNA isolated from fecal material is often of low quantity and quality (Taberlet et
al 1996) In addition, epitiielial cells usually are distributed unevenly (Kohn et al 1995)
and our fecal subsamples may not have included tiie cells required for DNA isolation.
Fecal material may also contain Taq DNA polymerase or PCR inhibitors, however, tiiis
problem can be reduced by using tiie silica-based extraction method (Boom et al 1990,
H6SS and Paabo 1993, Kohn et al 1995) Our modest DNA isolation success was
attnbuted to low-quality and low-quamity DNA found on scats Furthermore, the scats
we tested were dry-stored for up to 5 years at the time we conducted DNA analysis.
Reed et al (1997) and Lucchini et al (2002) reported that fecal sample age affected DNA
isolation success and suggested that fresh scats would be more suitable for DNA analysis
-Although our DNA isolation success (24%) was low, we found, as did Foran et al
(1997), that a scat's physical appearance was not a definitive guide to the DNA quality
a\ailable Another possibility influencing our low DNA isolation success could have
been that some of the scats were deposited by non-target species whose DNA could not
be amplified with the canid-specific primers designed for wolf and coyote that we used
We found, however, that the targeted species could be identified if a PCR product could
be obtained, since DNA too degraded to amplify produced no results as opposed to
incorrect results (Foran et al 1997) Our results were consistent with the findings of
Pilgrim et al (1998) that wolf and coyote mtDNAs were distinct and could be
differentiated by a single restriction site and length polymorphism We recognize that
there is a possibility that a low percentage of the scats identified as wolf could have been
deposited by feral dogs or wolf-dog hybrids if they existed within the BRWRA.
29
Therefore, we recommend that ftiture wolf DNA research utilize primers (Foran et al.
1997) that differentiate between wolf and dog DNA,
With a sample size of 47 scats identified to species using DNA analysis, we
suggest that our results be interpreted with caution Our resuhs demonstrated, however,
that identification of Mexican wolf and coyote scats using DNA analysis was more
accurate than identification methods previously available Molecular scatology can
facilrtate the identification of species, individuals, their gender, food habhs, and
pathology This would require an experimental design with extended systematic transects
from which fresh fecal samples are obtained, coupled with an appropriate preservation of
fecal material and DN.A isolation method (Reed et al 1997, Wasser et al 1997, Frantzen
et al 1998, Taberlet et al 1999, Lucchini et al 2(X)2), and using appropriate species-
sp>ecific primers (Foran et al 1997). These data could then be used further to estimate
home range (Adams et al 2(K)3), reproductive patterns, kinship stmcture and population
size (Kohn and W ayne 1997) Molecular scatology also has potential to detect
hybndization (Lehman et al 1991, Wayne et al 1992, Gondii et al 1994, Pilgrim et al
1998. Vila and Wayne 1999, Adams et al 2003) Finally, these data could be used for
validating the presence of wolves in livestock depredation incidences
Our resuhs suggest that previous diet studies using traditional scat identification
methods may have misrepresented the diets of both the North American gray wolf and
coyote where the 2 species were sympatric Fecal DNA analysis provides an accurate
method for assessing the visual identification of scat samples collected from the field and
improves diet analysis (Reed et al 1997) Molecular scatology appears to have
30
significant potential as a noninvasive sampling technique to momtor and manage free-
ranging Mexican wolves where the subspecies is sympatric with other carnivore species
Acknowledgements
The United States Fish and Wildlife Service funded this research and provided
scats from captive Mexican wolves The University of New Mexico and Arizona
Veterinary Diagnostic Lab provided blood samples from free-ranging Mexican wolves
The Museum of Texas Tech University provided coyote and rodent tissue samples.
Kaiser von Stockwerk generously provided domestic dog scats A Brown, C C.
Perchellet, and Drs F Hoffinan and J Wickliffe contributed invaluable assistance and
dedication in the DN.A lab Dr D B Wester facilitated the statistical analysis This is a
Texas Tech University. College of Agriculmral Sciences and Natural Resources technical
fwjblication T-X-.\XX
31
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39
FIELD SCATS TISSUE Wl _Ci W2 C2
KNOWN SCATS Wl DJ £ 1
250 bp ^
150 b p ^
Figure 3 1 Agarose gel showing a pxDrtion of the mtDNA control region (D-loop) amplified via Pilgrim et al (1998) canid-specific primers (Mexican wolf and dog, 164 bp; coyote 160 bp) Lanes 1 and 2 are field-collected scats Mexican wolf (WI) and coyote (CI) Lanes 3 and 4 are tissues Mexican wolf blood (W2) and coyote hver (C2) Lane 5 (S) is a 50 bp DNA size standard Lanes 6 through 8 are known scats: Mexican wolf (W I), domestic dog (Dl), and coyote (CI)
40
DIGESTED Wl W2
UNDIGESTED CI C2 C3
250 bp ^
150bp->
100bp->
Figure 3 2 Agarose gel showing restriction fragment digestion with BstN I of mtDNA control region (D-loop) purified polymerase chain reaction (PPCR) isolated from Mexican wolf and coyote scats The first lane is a 50 bp DN.A size standard Lanes 2 and 3 show digested Mexican wolf mtDNA (W1-W2, 113 bp), and the last 3 lanes show undigested coyote (C1-C3, 160 bp)
41
V5
« -
35 -
X -
25 -
2D -
35 S mm
27 8 ^u^_r-
r =22 8mm
174 mm
x = 26.0 mm
16.3 nun
Coyote Species
Mexican wolf
Figure 3 3 Comparison of diameters of coyote scats ((// = 21. range 17 4 to 27 8 m, X = 22 8 mm) and Mexican wolf scats {n = 26, range 16 3 to 35 8 mm, x = 26 0 mm) idemified with fecal DN.A analysis
42
Table 3 1 Comparison of accuracy of predicting which species (Mexican wolf or coyote) deposited a scat using discriminant analysis based on combination of 3 measurements taken from scats identified to species with DNA analysis Scats were collected in southeastern Arizona and southwestem New Mexico from April 1998 to October 2001
I 2 3 4
Classification Diameter (mm) Diameter and mass (g) Diameter and length Diameter, mass and length (cm)
Coyote (%) 81 86 68 79
Mexican wolf (%) 50 65 59 55
43
Table 3.2. Locations of scats (n = 47) identified as Mexican wolf or coyote with DNA analysis Scats were collected in southeastern Arizona and southwestem New Mexico from April 1998 to October 2001
Location Forest trails Forest roads and highways
Forest roads Forest 2-tracks Highway
Elk carcass Mexican wolf den Opened release pen Otiier Total
Mexican wolf 10 10
1 1 0 4 26
6 3 1
11 6
0 0 2 2
21
Coyote
4 2 0
Total 21 16
1 1 2 6 47
44
CHAPTER IV
DIETS OF FREE-RANGING MEXICAN GRAY WOLVES
IN ARIZONA AND NEW MEXICO
Abstract
There were no systematic diet smdies of Mexican gray wolves (Canis lupus
baileyi) before their extupation by the late 1960s from the southwestem United States.
We collected carnivore scats (n = 1,682) from the Apache and Gila National Forests of
Arizona and New Mexico from April 1998 through October 2001 and identified the scats
to species using traditional field methods (i e , diameter, location, and sign) and odor
We verified the accuracy of scat identification with fecal DNA analysis (molecular
scatology, n = 26, Reed 2004) to determine the diets of free-ranging Mexican wolves in
Arizona and New Mexico We analyzed scats > 28 mm diameter (n = 55) collected from
areas where Mexican wolf packs (n = 6) were fed supplemental food items and
determined if the packs consumed non-supplemental food items to detect a shift in diet as
they acclimated to a wild existence We foimd a difference (Go, = 12 995, P = 0 023) m
diet composition among packs, with the Cienega and Hawks Nest packs consuming more
non-supplememal food hems than the Lupine, Campbell Blue, Mule and Pipestem packs.
We analyzed Mexican wolf scats (w = 251) identified with our refined traditional field
methods established with DNA analysis (Reed 2004) and found the diet composition of
tiiose scats consisted of large-sized food items (92 8% percent frequency of occurrence
or mule deer (males < 102 3 kg, females ^ 56 8 kg, AGFD, unpublished dau). When
compared to previous diet studies for North American gray wolves, our resuhs suggest
that Mexican gray wolves consumed a higher proportion of large-sized native ungulates
than their northern counterparts This may have been the result of our conservative
identification of Mexican wolf scats using diameters ^ 28 mm, which may have biased
our diet analysis results towards the larger prey commonly found in large diameter scats
(Daimer and Dodd 1982) Additionally, previous gray wolf diet smdies included scats
collected from den and rendezvous sites and kill or carcass shes, while our Mexican wolf
scats were collected from all locations frequented by the subspecies, during all seasons,
and 2 den srtes
Our results indicate that elk aduhs and calves were the primary food source for
Nfexican wolves in Arizona and New Mexico from April 1998 through October 2001
Gray wolves in differem areas rely on different prey, and usually the wolfs diet is
compnsed of 1 or 2 species (Mech 1970) Elk were the most abundant and largest prey
available whhin the BRWRA (AGFD, unpublished data, USFS, unpubhshed data)
Although we did not study prey selection, we were curious why Mexican wolves
61
consumed mostiy elk aduhs and calves We can only hypothesize based on previous
lueramre of prey selection studies of gray wolves First, the density of elk within
Arizona and New Mexico was unknown, however, elk densrty was reported to be high
(Ballard et al 1998. AGFD, unpublished data) Therefore, h is unknown if the elk herd
within the BRWRA had neared or reached ecological carrying capacity. Furthermore, we
did not know if elk were subjected to winter severity (Mech et al 2001), malnutrition,
disease, or injunes or death from human activity ( e g , hunting and vehicles) that possibly
played a role in the Mexican wolfs consumption of elk One reason that a large
proportion of elk remains were found in Mexican wolf scats may have been because of
the low-densrty, early colonizing stage of wolves (Fritts and Mech 1981. Boyd et al
1994) These authors, as did Carbyn (1974. 1983) and Huggard (1992), found that
wolves primarily preyed upon the most vulnerable ungulates juvenile, old, or post-mt
males These data and ours suggest low-density, colonizing Mexican wolves may have
preyed upon vulnerable elk at a higher rate than other wolves in established northern
populations
Another reason why Mexican wolves consumed primarily elk may be because of
wolf-naive elk Although the resident elk population had been exposed to other predators
(i e , mountain lions, black bears, and coyotes), the elk had not been exposed to wolves.
This may have increased the vulnerability of resident elk that had never seen wolves until
confronted with them in 1998 Naive prey confronted with new predators have been less
wary than prey previously exposed to such danger (Byers 1998, Berger 1999, 2001)
62
To answer why Mexican wolves consumed primarily elk, ftuther study would be
required Mexican wolves are 1 of the 4 major predator species in Arizona and New
Mexico, and little research has been conducted on the other wild carnivores (i.e.,
mountain lion, black bear, and coyote) that now share the same prey base A muhi-
carmvore prey selection study would provide the information necessary for optimal
management of predators and then prey within Arizona and New Mexico
Our estimates of the diets of free-ranging Mexican gray wolves in Arizona and
New Mexico were based on a small sample of scats This is a result of our conservative
approach to identif>ing Mexican wolf scats based on DNA analysis and refined
traditional identification methods (i e , > 28 mm diameter, den site locations, and tracks)
Our results suggest that our refined traditional scat identification methods may have
biased estimates of the diets of Mexican wolves toward large ungulate food items WTien
researching the diets of colonizing and established wolf populations, h is important to
provide wildlife managers and the public whh accurate information We recommend that
future gray wolf diet studies incorporate DNA analysis of scats to ensure that only gray
wolf scats are included in diet analyses for the species This approach could prove
beneficial in resolving human-wolf conflicts in areas where gray wolves are reintroduced
or recovering
63
Acknowledgements
The Unhed States Fish and Wildlife Service funded this research The Mexican
wolf Interagency Field Team (IFT, i e , US. Fish and Wildlife Service, Arizona Game
and Fish Department, New Mexico Department of Game and Fish, USDA APHIS
Wildlife Services, and U S Forest Service) p)ersonnel assisted with the collection of scats
and provided Mexican wolf location data The United States Forest Service Alpine and
Clifton Ranger District personnel assisted whh logistics This is a Texas Tech
University, College of Agricultural Sciences and Natural Resources technical publication
T-X-XXX
64
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70
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Table 4 2 Comparison of diet composhion found in scats (n = 55) ^ 28 mm diameter from areas where Mexican gray wolf packs (n = 6) were fed supplemental food hems (i e , carnivore logs and road-killed elk, deer, and jackrabbrt) to determine presence of non-supplemental food items ( eg , elk adults and calves, deer adults and fawns, domestic bovine, and insects) Scats were collected from April 1998 to October 2001 in Arizona and New Mexico and compared to Mexican wolf Interagency Field Team dated supplemental food records Comparison values are express as percent frequency of occurrence (PFO)
Pack Lupine Campbell Blue Mule Pack Pipestem Cienega Hawks Nest
Total
No food rtems 3
- I T
8 5 5 12 55
SF' 3 16 5 2 1 2 29
Food hems NSF^
1 6 3 3 4 10 27
NSF PFO (%)' 25 0 a 27.3 a 37.5 a 60 0ab 80 0ab 833 b 49 1
'SF = supplemental food items * NSF = non-supplemental food hems *PFO (%) = percent frequency of occurrence Percentages followed by the same lower
case letter were not significantly different (P>0 05, G-test. adjusted for continuity)
72
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73
Table 4 4 Comparison among years (n = 4, 1998-2001) of diet composhion found in scats (n = 251) of free-ranging Mexican gray wolves collected from April 1998 to October 2001 in Arizona and New Mexico Scats were identified to species by refined tiaditional field methods (i e, diameter, location, and sign; Reed 2004). Food rtems were combined as large-sized (i e . aduh and young ungulates) food items and medium- and small-sized food items (i e . medium- and small-sized mammals, birds, insects, and vegetation). Non-food rtems were not included. Comparison values are expressed as percent frequency of occurrence (PFO)
Year 1998 1999 20OO 2001 Total
Large-sized food hems
135 19 53 39
246
Medium - and small-sized food rtems
14 1 2 2 19
Large-sized food hems PFO (%)'
90.6 95.0 964 95 1
'PFO ("*/o) = percent frequency of occurrence, none differed significantly (P>0 05, G-test, adjusted for cominuity)
74
Table 4 5 Comparison between seasons (;i = 2, fall-winter versus spring-summer) of diet composhion friund in scats (/i = 251) of free-ranging Mexican gray wolves in Arizona and New Mexico (April 1998 - October 2001) Scats were identified to species by refined traditional field methods (i e , diameter, location, and sign. Reed 2004) Food items were combined as large-sized (aduh and young ungulates) food hems and medium-and small-sized food rtems (i e , medium- and small-sized mammals, birds, msects, and vegetation) Non-food rtems were not included Comparison values are expressed as percent frequency of occurrence (PFO)
Season fall-winter spring-summer Total
Large-sized food items
36 210 246
Medium- and small-sized food hems
4 15 19
Large-sized food rtems PFO (%)'
900 933
'PFO (%) = percent frequency of occurrence, none differed significantly (P > 0 05, G-test. adjusted for continuity)
75
Table 4 6 Comparison of diet composhion among packs (n = 4) found in free-ranging Mexican wolf scats (n = 251) collected from April 1998 to October 2001 in Arizona and New Mexico Scats were identified by refined traditional field methods (i.e., diameter, location, and sign. Reed 2004) Food items were combined as large-sized (i.e., adult and young ungulates) food rtems and medium- and small-sized food hems (i e., medium- and small-sized mammals, bhds, insects, and vegetation) Non-food items were not included. Comparison values are expressed as percent frequency of occurrence (PFO).
Pack Hawks Nest Campbell Blue Francisco Cienega Total
Large-sized food rtems
66 98 20 26
210
Medium- and small-sized food rtems
8 9 0 0 17
Large-sized food hems PFO (%)'
892 91 6
100 0 1000
'PFO ("o) = percent frequency of occurrence, none differed significantly (P > 0 05, G-test, adjusted for continuity)
76
Table 4.7. Food items (n = 33) found in free-ranging Mexican gray wolf scats (n = 26) collected from April 1998 to October 2001 in Arizona and New Mexico. Scats were identified by DNA analysis (Reed 2004). Non-food items were not included. Comparison values are expressed as percent frequency of occurrence (PFO).
Medium- and Small-sized food rtems Javelina (Dicotyles tajacu) Red squirrel (Tamiasciurus hudsonicus) Mouse (Peromyscus spp.) Unknown rodent Birds Insects
Total number of food items Total number of scats Number food items per scat
No.
5 14 2 I 2
1 I 2 2 2 1
33 26
I 27
PFO (%)'
15.2 42.4 6.1 3.0 6.1
3.0 3.0 6 1 6.1 6 1 30
'PFO (%) = percent frequency of occurrence
77
Table 4 8 Comparison of diet composhion of Mexican wolf scats (n = 277) collected from .April 1998 to October 2001 in Arizona and New Mexico and identified using 2 methods DN.A analysis (n = 2b) and refined traditional (n = 251, i e , > 28 mm diameter, 2 den srtes, and ttacks) Food items were combmed as large-sized (i e , aduh and young ungulates) food items and medium- and small-sized food hems (i e., medium- and small-sized mammals, bhds, insects, and vegetation) Non-food hems were not mcluded. Comparison \^ues are expressed as percent frequency of occurrence (PFO)
Method DN.A analysis Refined traditional
identification Total
Large-sized food hems
24 246
270
Medium- and small-sized food hems
9 19
28
Large-sized food hems PFO (%)'
72.7 a 92 8 b
'PFO (°'o) = percent frequency of occurrence Percentages followed by the same lower case letter are not significantly different (P > 0 05, G-te^, adjusted for continuity)
78
Table 4 9, Comparison of diet composhion found in free-ranging Mexican wolf scats (n = 26) and sympatric coyote scats (/»= 21) collected from April 1998 to October 2001 in Arizona and New Mexico Scats were identified by DNA analysis (Reed 2004). Food hems were combmed as large-sized (i e . aduh and young ungulates) food hems and medium- and small-sized food hems (i e , medium- and small-sized mammals, birds, insects, and vegetation) Non-food hems were not included Comparison values are expressed as percent frequency of occurrence (PFO)
Species Mexican gray wolf Coyote Total
Large-sized food hems
24 15 39
Medium- and small-sized food hems
9 26 35
Large-sized food rtems PFO (%)'
72.7 a 36 6 b
'PFO l" o) = percem frequency of occurrence Percertages followed by the same lower case letter are not significantly different (P > 0 05, G-test. adjusted for continuity)
79
Table 4.10. Food items found in free-rangmg Mexican gray wolf scats (n = 26) and sympatric coyote scats (n = 21) collected from April 1998 to October 2001 in Arizona and New Mexico. Scats were identified by DNA analysis (Reed 2004). Non-food hems were not mcluded. Comparison values are expressed as percent frequency of occiurence (PFO).
Total nomter of food items Total mmter of scats Noraber food items per scat
Mexicanwolf No. PFO(%)'
5 15.2 14 42.4
2 6.1 — — 1 3.0 2 61
1 30 — — 1 30 — — — — 2 61 2 6 1 — — 2 6 1
1 3.0 _ _ 33 26
1.27
No.
2 7
1 2 -3
1 4 1 4 1 1 — 1 — 1 7 5
41 21
1.95
Coyote HfO(%)
4.9 17.1
2.4 4.9 — 7.3
2.4 9.8 2.4 9.8 2.4 2.4 — 2.4 — 2.4
17.1 12.2
'PFO (•/•) = percem frequency of occurrence
80
Table 4 11 Comparison of diet composhion found in free-ranging Mexican wolf scats (n = 277) and diet composition reported in other North American gray wolf diet studies (n = 7) Mexican wolf scats (/; = 270) were identified by refined traditional field methods (" = 251) and DNA analysis (n = 26. Reed 2004) Scats were collected from April 1998 to October 2001 in Arizona and New Mexico Food items were combined as large-sized (i e , adult and young ungulates) food items and medium- and small-sized food hems. Non-food items were not included Comparison values are expressed as percent frequency of occurrence (PFO)
Source Ballard etal (1987) Thompson (1952) Spaulding et al (1997) Murie (1944) Mech (1966) Cowan (1947) .Arjo etal (2002) This study
Large-sized food items
3,263 421
2,402 935 392 353 753 270
Medium- and small-sized food hems
2,316' 292'
1,082 406 124 94
155 28
Large-sized food hems PFO (%)'
58 5 a 59 0 a 68 9 b 697 b 76 0 c 79 0 cd 829 d 90 6 e
'PFO (" o) = percent frequency of occurrence Percentages followed by the same lower case letter are not significantly different (P > 0 05. G-test, adjusted for continuity)
^Data included unidentified ungulates and undefined "unidentified" food hems 'Data mcluded unidentified non-food items
81
CHAPTER V
SUMMARY
This was the first systematic stiidy to determine the diets of free-ranging Mexican
gray wolves (Carus hipus baileyi) in tiie soutiiwestem United States. We collected
carnivore scats (n = 1,682) from tiie Bhie Range Wolf Recovery Area (BRWRA) in
Arizona and New Mexico from April 1998 tiirough October 2001. We identified tiie
scats to species using ti^dhional field methods (i.e., diameter, location, and sign) and
odor. We then used fecal DNA analysis (molecular scatology) to verify the accuracy of
identifying Mexican wolf scats with tradhional methods and odor. DNA analysis of
Mexican wolf (n = 26) and sympatric coyote (» = 21) scats showed a 79% overlap in
diameto- size (Mexican wolf; 16 3 to 35 8 mm, coyote, 17 4 to 27 8 mm) and scats ^ 28
mm diameter were deposhed by Mexican wolves We found a difference (/ = -2.428,
P = 0 019) between diameter means for the 2 species (Mexican wolf F= 26 0 mm, coyote
X = 22.8 mm). From our DNA analysis resuhs, we refined the traditional methods for
identifying Mexican wolf scats as diameters ^ 28 mm, den site locations, and tracks, as
well as scats identified whh DNA analysis Diet analysis of Mexican wolf scats (n = 55)
with diameters > 28 mm collected from areas where 6 packs received supplemental
carnivore logs and road-killed elk, deer, and jackrabbit showed that non-supplemental
food items were consumed by Hawks Nest and Cienega packs (G«^ = 12.995, P = 0.023),
but not by Lupine, Campbell Blue, Mule or Pipestem packs. Diet analysis of Mexican
wolf scats (n = 251) identified according to > 28 mm diameter, den she location, and
82
tracks revealed a diet composhion consisting mainly of large-sized food hems (92.8%
PFO). primarily elk aduhs (36 6% PFO) and calves (36,2% PFO). There was no
difference in diets among years (n = 4. Gad/ = 2 588, P = 0.460), between seasons (n = 2,
Gad, = 0 490. P = 0 484), or among packs (n = 4, Gad, = 7 719, P = 0.052). We found a
difference (G^^ = 9 761, P = 0 002) in diet composhion of Mexican wolf scats identified
with our refined ttaditional methods (n = 251) when compared to that of DNA analysis
identified scats (n = 26) There were more large-sized food items in the scats identified
with our refined ttaditional method than found in scats identified with DNA analysis.
There was no difference (/ = -1 95, P = 0 001) between diameter means (refined
traditional method x = 29 3 mm, DNA method x = 26 0 mm) There was also no
difference (t = \ 50, P = 0 005) in number of food items per scat when comparing the 2
methods (refined tradhional method x 1 06 food items per scat, DNA method x = 1 27
food hems per scat) We found a difference ((}ad, = 9 647, Z' = 0 002) in diet composhion
of Mexican wolves and sympatnc coyotes, with Mexican wolf diets consisting primarily
of large-sized food hems (72 7°o PFO) and sympatnc coyote diets consisting primarily of
medium- and small-sized food items (63 4% PFO) There found a difference between the
2 species' scat diameter means {t = -2 428. P = 0 019, Mexican wolf x = 26 0 mm,
coyote X = 22 8 mm) There was also a difference (/ = 2 849, P = 0 007) between number
of food items per scat for the 2 species (Mexican wolf F = 1 27 food items per scat,
coyote x = 1 95 food items per scat) Finally, we found a difference (Gad, = 462 492,
/> = < 0 0001) in diet composhion of Mexican wolves when compared to diets reported
previously for other North American gray wolves Mexican wolf diet analysis revealed
83
more large-sized food hems (90 6% PFO) than that reported in 7 northern gray wolf diet
smdies (range 58 5% to 82 90/0 PFO) Our results imply that free-ranging Mexican gray
wolves in .\nzona and New Mexico consumed more large-sized food hems, primarily elk
aduhs and calves, than sympatric coyotes and the larger, northern gray wolves. This
information could prove useftil in managing both Mexican wolf and prey populations, as
well as determining the presence of Mexican wolves in depredation incidences in Arizona
and New Mexico
84
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