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Wading Bird Reproductive and Physiological Responses to Environmental Disturbance in a Managed Lake Ecosystem
Title
Wading Bird Reproductive and Physiological Responses to Environmental Disturbance in a Managed Lake Ecosystem.
Creator
Chastant, Jennifer E., Gawlik, Dale E., Florida Atlantic University, Charles E. Schmidt College of Science, Department of Biological Sciences
Abstract/Description
Wetlands are some of the most diverse and productive ecosystems on earth. Water-level fluctuations determine the ecological function of shallow lakes and wetlands. Currently, anthropogenic modification to water-level fluctuations is the leading source of ecological degradation in lake and wetland ecosystems worldwide. I used wading birds nesting in Lake Okeechobee, as a model system to address the challenges of environmental restoration within an ecosystem greatly impacted by anthropogenic...
Show moreWetlands are some of the most diverse and productive ecosystems on earth. Water-level fluctuations determine the ecological function of shallow lakes and wetlands. Currently, anthropogenic modification to water-level fluctuations is the leading source of ecological degradation in lake and wetland ecosystems worldwide. I used wading birds nesting in Lake Okeechobee, as a model system to address the challenges of environmental restoration within an ecosystem greatly impacted by anthropogenic activities. Specifically, I 1) identified environmental factors most important for predicting the number of wading bird nests, 2) tested the assumptions of both the match-mismatch and the threshold hypothesis by modeling the relationship between nesting success and prey density with foraging habitat availability, and 3) measured the stress response of Great (Ardea alba) and Snowy Egrets (Egretta thula) to hydrologically-mediated changes in food availability. Collectively, the results suggest that the number of nests was greatest when area of nesting substrate was high and water-levels were moderate (3.9 - 4.4 m). Nest numbers dropped when either nesting substrate or foraging habitat was limited. My investigation into the predictions of the match-mismatch and threshold hypotheses found that indeed, prey density can reduce or intensify the effects of a mismatch event. The interaction of prey density and foraging habitat availability was significant and positive in both models. Saturation thresholds existed for both fledging success (147 prey (m^2)^-1) and total productivity (189 prey (m^2)^-1), above which high concentrations of prey could sustain nesting when foraging habitat availability was low. Finally, my studies of the stress response support the hypothesis that hydrologic factors associated with prey availability play an important role in regulating nesting patterns, although the level of food limitation the birds experience at the lake was not as severe as expected. Model selection identified foraging habitat availability as most influential to the nestling Great Egret stress response, whereas foraging habitat availability and prey density both influenced nestling Snowy Egret stress response. Moreover, the Snowy Egret stress response was more sensitive to changes in prey availability than was the Great Egret stress response. Temperature and foraging conditions influenced yolk corticosterone concentrations for both egret species.
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Date Issued
2016
PURL
http://purl.flvc.org/fau/fd/FA00004779
Subject Headings
Wetland ecology., Estuarine ecology., Water birds--Habitat., Predation (Biology)
Format
Document (PDF)
Foraging ecology of wading birds in a sub-tropical intertidal zone
Title
Foraging ecology of wading birds in a sub-tropical intertidal zone.
Creator
Calle, Leonardo, Gawlik, Dale E., Florida Atlantic University, Charles E. Schmidt College of Science, Department of Biological Sciences
Abstract/Description
The first of five chapters describe the study area and study species, including a short description about the impetus for this research. The second chapter describes a unique hydrologic model for application in tidal ecosystems. The second chapter represents new information on the effects of various abiotic and biotic factors on foraging wading birds in this highly dynamic environment. The third chapter identifies important factors affecting the abundance of foraging wading birds in...
Show moreThe first of five chapters describe the study area and study species, including a short description about the impetus for this research. The second chapter describes a unique hydrologic model for application in tidal ecosystems. The second chapter represents new information on the effects of various abiotic and biotic factors on foraging wading birds in this highly dynamic environment. The third chapter identifies important factors affecting the abundance of foraging wading birds in intertidal environments. The fourth chapter presents a study of the foraging habitat preferences of two wading bird species in intertidal environments. The fifth chapter describes a conceptual model of wading bird foraging ecology and a predictive model of foraging habitat in intertidal zones. The conceptual model captures the major drivers and linkages between the abiotic and biotic variables thought to affect wading bird foraging abundance in intertidal habitats. The conceptual model also identifies major knowledge gaps in our understanding of foraging ecology of wading birds in coastal intertidal areas. The predictive model of foraging habitat is meant to be used by resource managers, but its framework may be useful for ecological studies in general. The final and sixth chapter provides a summary of all the major findings. Each chapter has been written so as to be independent of the other chapters. As such, a full background, along with a discussion of the relevance of the chapter's findings is provided for each chapter.
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Date Issued
2014
PURL
http://purl.flvc.org/fau/fd/FA00004087
Subject Headings
Habitat selection, Population biology, Predation (Biology), Water birds -- Geographical distribution, Water birds -- Habitat
Format
Document (PDF)
Diet of the Purple Swamphen in south Florida and invasion pathways of nonnative avian species in Florida
Title
Diet of the Purple Swamphen in south Florida and invasion pathways of nonnative avian species in Florida.
Creator
Callaghan, Corey, Gawlik, Dale E., Florida Atlantic University, Charles E. Schmidt College of Science, Center for Environmental Studies
Abstract/Description
The spread of nonnative invasive species has become the second greatest threat to global biodiversity, making management of invasive species a critical component of the conservation of biodiversity worldwide. Managers and conservation biologists often lack basic life history data, as well as quantitative and theoretical models to predict risk of invasion or other negative effects. I contribute information to both categories by providing life history information (diet and morphology) of the...
Show moreThe spread of nonnative invasive species has become the second greatest threat to global biodiversity, making management of invasive species a critical component of the conservation of biodiversity worldwide. Managers and conservation biologists often lack basic life history data, as well as quantitative and theoretical models to predict risk of invasion or other negative effects. I contribute information to both categories by providing life history information (diet and morphology) of the Purple Swamphen (Porphyrio porphyrio) and by characterizing the invasion pathways that nonnative avian species in Florida follow. I found Purple Swamphens are predominantly eating and selecting for Eleocharis cellulosa. Additionally, there is a large amount of variation in nonnative avian species’ propensity to colonize natural habitat and the time it takes to do so. Nine out of 15 species investigated colonized natural habitat and the time it took them to do so ranged from 8 to 41 years. It is through a combination of various techniques that ecologists will begin to fully understand the importance of studying nonnative species as well as reducing the impact that nonnatives have on native ecosystems.
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Date Issued
2015
PURL
http://purl.flvc.org/fau/fd/FA00004433, http://purl.flvc.org/fau/fd/FA00004433
Subject Headings
Birds--Behavior., Birds--Habitat., Adaptation (Biology), Biological invasions., Introduced organisms., Ecological risk assessment--Florida.
Format
Document (PDF)
A habitat suitability model for wading birds in a large subtropical lake: linking hydrologic fluctuations and nesting
Title
A habitat suitability model for wading birds in a large subtropical lake: linking hydrologic fluctuations and nesting.
Creator
Botta, Richard A., Gawlik, Dale E., Florida Atlantic University, Charles E. Schmidt College of Science, Department of Biological Sciences
Abstract/Description
Anthropogenic hydrologic alterations can affect the quality of lake littoral zone habitats for wading birds, such as the great egret (Ardea alba), snowy egret (Egretta thula), and white ibis (Eudocimus albus). One such lake in Florida, Lake Okeechobee, has experienced a marked decline in wading bird nesting since the 1970’s, concomitant with changes in lake level management. It’s hypothesized that a reduction in foraging habitat has led to the nesting decline; however, there is little...
Show moreAnthropogenic hydrologic alterations can affect the quality of lake littoral zone habitats for wading birds, such as the great egret (Ardea alba), snowy egret (Egretta thula), and white ibis (Eudocimus albus). One such lake in Florida, Lake Okeechobee, has experienced a marked decline in wading bird nesting since the 1970’s, concomitant with changes in lake level management. It’s hypothesized that a reduction in foraging habitat has led to the nesting decline; however, there is little quantitative evidence of this link. A habitat suitability model was developed for Lake Okeechobee wading birds that incorporate the spatial and temporal dynamics of environmental factors that affect wading bird foraging and tests whether foraging habitat is linked to numbers of nests.
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Date Issued
2014
PURL
http://purl.flvc.org/fau/fd/FA00004082
Subject Headings
Birds -- Florida -- Lake Okeechobee -- Geographical distribution, Estuarine ecology -- Florida -- Lake Okeechobee, Restoration ecology -- Florida -- Lake Okeechobee, Water birds -- Habitat
Format
Document (PDF)
Development, evaluation, and application of spatio-temporal wading bird foraging models to guide everglades restoration
Title
Development, evaluation, and application of spatio-temporal wading bird foraging models to guide everglades restoration.
Creator
Beerens, James M., Noonburg, Erik G., Florida Atlantic University, Charles E. Schmidt College of Science, Department of Biological Sciences
Abstract/Description
In south Florida, the Greater Everglades ecosystem supports sixteen species of wading birds. Wading birds serve as important indicator species because they are highly mobile, demonstrate flexible habitat selection, and respond quickly to changes in habitat quality. Models that establish habitat relationships from distribution patterns of wading birds can be used to predict changes in habitat quality that may result from restoration and climate change. I developed spatio-temporal species...
Show moreIn south Florida, the Greater Everglades ecosystem supports sixteen species of wading birds. Wading birds serve as important indicator species because they are highly mobile, demonstrate flexible habitat selection, and respond quickly to changes in habitat quality. Models that establish habitat relationships from distribution patterns of wading birds can be used to predict changes in habitat quality that may result from restoration and climate change. I developed spatio-temporal species distribution models for the Great Egret, White Ibis, and Wood Stork over a decadal gradient of environmental conditions to identify factors that link habitat availability to habitat use (i.e., habitat selection), habitat use to species abundance, and species abundance (over multiple scales) to nesting effort and success. Hydrological variables (depth, recession rate, days since drydown, reversal, and hydroperiod) over multiple temporal scales and with existing links to wading bird responses were used as proxies for landscape processes that influence prey availability (i.e., resources). In temporal foraging conditions (TFC) models, species demonstrated conditional preferences for resources based on resource levels at differing temporal scales. Wading bird abundance was highest when prey production from optimal periods of wetland inundation was concentrated in shallow depths. Similar responses were observed in spatial foraging conditions (SFC) models predicting spatial occurrence over time, accounting for spatial autocorrelation. The TFC index represents conditions within suitable depths that change daily and reflects patch quality, whereas the SFC index spatially represents suitability of all cells and reflects daily landscape patch abundance. I linked these indices to responses at the nest initiation and nest provisioning breeding phases from 1993-2013. The timing of increases and overall magnitude of resource pulses predicted by the TFC in March and April were strongly linked to breeding responses by all species. Great Egret nesting effort and success were higher with increases in conspecific attraction (i.e., clustering). Wood Stork nesting effort was closely related to timing of concurrently high levels of patch quality (regional scale) and abundance (400-m scale), indicating the importance of a multi-scaled approach. The models helped identify positive and negative changes to multi-annual resource pulses from hydrological restoration and climate change scenarios, respectively.
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Date Issued
2014
PURL
http://purl.flvc.org/fau/fd/FA00004078, http://purl.flvc.org/fau/fd/FA00004078
Subject Headings
Everglades National Park (Fla.) -- Environmental conditions, Restoration ecology -- Florida -- Everglades National Park, Water birds -- Florida -- Geographical distribution, Water birds -- Habitat -- Florida -- Everglades National Park, Wetland restoration -- Florida -- Everglades National Park
Format
Document (PDF)