Department of Wildlife Ecology and Conservation University of … · 2010. 8. 24. · Department of Wildlife Ecology and Conservation University of Florida. CERP Mod Waters Jetport

WADING BIRD NESTING AS A TOOL FOR UNDERSTANDING EVERGLADES

ECOLOGY A KEYSTONE INTEGRATOR AND GENERATOR OF TROPHICECOLOGY: A KEYSTONE INTEGRATOR AND GENERATOR OF TROPHIC

HYPOTHESES

iPeter FrederickDepartment of Wildlife Ecology and Conservation

University of Florida

CERP

Mod Waters

Jetport and“Reccy”

Stork studies

Plume hunting and recovery

1900 20101925 1950 1975

g y

Ho: Wading bird nesting in EVER is primarily limited by food availability.

-Timing of nesting during peak of food availability.

Predation disease and nesting substrate are NOT limiting factors- Predation, disease and nesting substrate are NOT limiting factors.

- Food availability limiting in other parts of the world.

- Food addition experiments support predictions.

- Food limitation (reversals, droughts) linked to poor reproduction.

Everglades T hi

Regional‐scaleenvironment

Local‐scaleenvironment

TrophicHypothesis

Vegetation structureLandscape configuration

Nutrient levelsFrequency of drying

Time since end of last dryingDuration and severity of last drying event

Periphyton standing stock and composition

Large fish population size

Local‐scale environmentMicrotopographyWater depth

Water recession ratePrey population size

Prey availability (dry season prey concentrations )

Wading bird characteristics

(morphology, foraging behavior))

Habitat selection food intake foraging

)

Wading bird responses Habitat selection, food intake, foraging

aggregations, physiological condition

Nesting effort and productivity Mortality

responses

Population size

Predrainage characteristics:

1 High interannual variability in nesting numbers1. High interannual variability in nesting numbers

2. Nesting concentrated in coastal areas

3. Nesting numbers dominated by tactile foragers (ibises, storks).

4. Early nesting by storks (November, December)

5 Nest success high (storks)5. Nest success high (storks)

120,000

60,000

80,000

100,000

0

20,000

40,000

1931

1934

1937

1940

1943

1946

1949

1952

1955

1958

1961

1964

1967

1970

1973

1976

1979

1982

1985

1988

1991

1994

1997

Predrainage characteristics: Why and how?

1 High interannual variability in nesting numbers1. High interannual variability in nesting numbers

Obs: Pulses of ibis nesting following strong droughts

Ho: Droughts restructure opportunities for prey production

Prediction 1. Abnormally high ibis nesting # following droughts

Prediction 2 Higher food availability following droughtsPrediction 2. Higher food availability following droughts

Monitor: “Ibis Supercolonies” A l b f ibi tAnnual numbers of ibis nestsHydropatternsmall fish and crayfish abundanceylarge predatory fish abundance

Everglades T hi



TrophicHypothesis












)




responses

Population size


2. Nesting concentrated in coastal areas.

OBS: Shift to freshwater nesting post drainageOBS: Shift to freshwater nesting post-drainagePrey denser in estuarine conditions

H E i d i i li k d f h iHo: Estuarine prey productivity linked to freshwater input

Prediction 1. Proportion coastal nesting increases with p grestoration of coastal freshwater flows

Prediction 2 Prey animal density and standing stock increasesPrediction 2. Prey animal density and standing stock increases with coastal freshwater flows.

Monitor: “Coastal nesting” performance measure N ti b i t lNesting numbers in coastal zonePrey animal production in coastal zone

Everglades T hi



TrophicHypothesis












)




responses

Population size


3. Nesting numbers dominated by tactile foragers (storks, ibises).

OBS: Storks, ibises give up foraging at high prey densities

Ho: High prey densities favor reproduction by tactile foragersHo: High prey densities favor reproduction by tactile foragers

Prediction 1. Hydrological restoration results in high qualityh (hi h d i i h i d fi h)prey patches (high density, right sized fish)

Prediction 2. Hydrological restoration results in higher ratioof tactile/visual foragers. g

Monitor: Ratio of White Ibis + Wood Stork/Great EgretHydrological restorationHydrological restorationquality of dry season prey patches

Everglades T hi



TrophicHypothesis












)




responses

Population size


4. Early nesting by storks (November, December).

OBS: Storks use short hydroperiod wetlands early in season

Ho: Short hydroperiod wetlands are critical for stork nestHo: Short hydroperiod wetlands are critical for stork nestinitiation because prey are concentrated early.

P di i 1 R i f h d i iPrediction 1. Restoration of hydropattern in entire systemresults in early season availability of prey.

Prediction 2. Stork nesting will shift to November/December

Monitor: Timing of stork nestingMonitor: Timing of stork nestingTiming and quality of prey patches


S S5. Stork, Spoonbill nest success: historical >> postdrainage.

OBS: Nest failures are related to timing of initiation.gEarly season prey availability extremely low at start of wet season.

Ho: Restored hydropattern increases early season preyavailability through altered depths and location.

Prediction 1. Restored hydropattern results in earlier nestingPrediction 2. Stork nesting becomes more successfulgPrediction 3. Stork nesting population will increase

Monitor: Timing and success of stork nestingMonitor: Timing and success of stork nestingStork population sizeRestoration of hydropattern.

Wading bird trophic predictions and monitoring

Annual systematic searches for nesting colonies

Counts of nesting species with historical informationCounts of nesting species with historical informationWood Storks, White Ibises, Snowy Egrets, Great Egrets, Roseate Spoonbills.

Wood Stork timing and nest success

Roseate Spoonbill nest success and foraging locations

H d i d

Salinity Confidence LevelHydroperiod

Disturbance history

Prey community

HighMediumUncertainLittle information

Nutrient availability

Composition Little information

Water depth

Prey density/SS Vegetation density

Drying rate

Prey size distribution

Food Availability

Nesting

Energy intake

Nesting substrateg

Nesting successRecruitment

Assumption: Everglades attributes drive Everglades nesting responses

Hydroperiod

Salinity Everglades attributes

Disturbance history

Prey communityComposition

Water depth

Prey density/SS Vegetation density

Drying rateNutrient availability

Prey size distribution

Energy intake

Food AvailabilityComparison Shoppingfor prey availability

Nesting

Nesting success

Nesting substrate

Recruitment

Department of Wildlife Ecology and Conservation University of … · 2010. 8. 24. · Department of Wildlife Ecology and Conservation University of Florida. CERP Mod Waters Jetport

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