department of wildlife ecology and conservation university of...
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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
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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
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: Why and how?
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
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: Why and how?
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
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: Why and how?
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
Predrainage characteristics: Why and how?
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