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Title: Habitat Suitabiility for white ibis, snowy egret and great egret at Lake Okeechobee, Florida.
Creator: Botta, Richard A., Gawlik, Dale E., Graduate College
Date Issued: 2013-04-12
PURL: http://purl.flvc.org/fcla/dt/3361908
Subject Headings: White ibis, Great egret, Egrets, Okeechobee, Lake (Fla.), Habitat suitability index models
Format: Document (PDF)

Title: Characteristics Affecting Prey Vulnerability and Avian Habitat Selection in the Florida Everglades.
Creator: Harris, Rachael L., Gawlik, Dale E., Florida Atlantic University
Abstract/Description: The vulnerability of prey to capture plays a fundamental role in determining overall prey availability for wading birds. Structural complexity can act to decrease prey vulnerability and influence foraging habitat selection. To determine how structural complexity can affect habitat selection I conducted a use vs. availability study throughout the Florida Everglades in 2005 and 2006. Results indicated that wading birds chose foraging sites that had less emergent vegetation and a thicker...
Show moreThe vulnerability of prey to capture plays a fundamental role in determining overall prey availability for wading birds. Structural complexity can act to decrease prey vulnerability and influence foraging habitat selection. To determine how structural complexity can affect habitat selection I conducted a use vs. availability study throughout the Florida Everglades in 2005 and 2006. Results indicated that wading birds chose foraging sites that had less emergent vegetation and a thicker flocculent layer relative to random sites. Submerged vegetation, and the height of emergent vegetation did not affect wading bird site selection. A difference in habitat selection between years was evident due to hydrological conditions. Ideal hydrological conditions are probably the most important parameter to wading bird success. Other factors affecting prey vulnerability became increasingly important in years of poor hydrology, probably because the penalty for choosing low quality foraging habitat would be greater than in years of more optimal conditions.
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Date Issued: 2007
PURL: http://purl.flvc.org/fau/fd/FA00000754
Subject Headings: Everglades (Fla), South Florida Water Management District (Fla ), Wildlife management--Florida--Everglades, Bird populations--Florida--Everglades, Water birds--Florida--Everglades, Wetland ecology--Florida--Everglades
Format: Document (PDF)

Title: Factors Affecting Wading Bird Prey Concentrations in the Everglades During the Dry Season.
Creator: P. Brian Garrett, Gawlik, Dale E., Florida Atlantic University
Abstract/Description: One factor that potentially controls the distribution and density of wading bird prey within open-water marsh habitats during seasonal drying events is the amount of available aquatic habitat, which is partly a function of the amount of microtopographic relief at a given location. To determine how microtopographic relief affects prey concentrations during dry-downs a simulation model was developed and run using empirical microtopographic data collected from the Everglades. The simulation...
Show moreOne factor that potentially controls the distribution and density of wading bird prey within open-water marsh habitats during seasonal drying events is the amount of available aquatic habitat, which is partly a function of the amount of microtopographic relief at a given location. To determine how microtopographic relief affects prey concentrations during dry-downs a simulation model was developed and run using empirical microtopographic data collected from the Everglades. The simulation suggests that those locations within the marsh with higher levels of microtopographic relief concentrate prey earlier during the dry-down period and potentially to greater densities overall. In addition, a model selection analysis was performed on field data to determine which set of factors displayed the greatest effects upon prey concentrations during drydown events. When examining the best selected a priori model it appears that the amount of available aquatic habitat, water depth, and macrophyte density have the strongest affects upon concentrations of prey during a seasonal drying event.
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Date Issued: 2007
PURL: http://purl.flvc.org/fau/fd/FA00000769
Subject Headings: Water birds--Florida--Everglades, Wetland ecology--Florida--Everglades, Bird populations--Climatic factors--Florida--Everglades
Format: Document (PDF)

Title: Foraging Habitat Modeling and Nesting Ecology of Wood Storks in Everglades National Park.
Creator: Herring, Heidi K., Gawlik, Dale E., Florida Atlantic University
Abstract/Description: Understanding the foraging and nesting ecology of Wood Storks will play an important role in Everglades restoration because this species has specific resource requirements during the breeding season which ultimately affect nest success. I conducted a foraging habitat use and selection study, which indicated that Wood Storks from coastal colonies, Paurotis Pond and Rodgers River Bay, require a narrow range of water depths in the mangrove-saltwater marsh ecotone near their colonies as well in...
Show moreUnderstanding the foraging and nesting ecology of Wood Storks will play an important role in Everglades restoration because this species has specific resource requirements during the breeding season which ultimately affect nest success. I conducted a foraging habitat use and selection study, which indicated that Wood Storks from coastal colonies, Paurotis Pond and Rodgers River Bay, require a narrow range of water depths in the mangrove-saltwater marsh ecotone near their colonies as well in the freshwater marsh habitats of the inland Everglades. Wood Storks nesting at the inland colony, Tamiarni West, relied heavily upon nearby freshwater marsh habitat and selected foraging sites associated with shrub swamp habitat as well as optimal water depths. The observational nesting ecology study of Wood Storks showed marked differences in parental nest attendance and food delivery rates between the two years of study, 2005 and 2006, which had different hydrological patterns.
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Date Issued: 2007
PURL: http://purl.flvc.org/fau/fd/FA00000761
Subject Headings: Habitat selection, Animal behavior, Wood stork--Habitat, Bird populations--Florida--Everglades National Park, Everglades National Park (Fla )
Format: Document (PDF)

Title: A tidal inundation model of shallow-water availability (TiMSA).
Creator: Calle, Leonardo, Gawlik, Dale E., Xie, Zhixiao, Johnson, Brian, Graduate College
Date Issued: 2013-04-12
PURL: http://purl.flvc.org/fcla/dt/3361914
Subject Headings: Ecology, Wading birds, Florida Keys (Fla.)
Format: Document (PDF)

Title: Everglades Florida Apple Snail Density.
Creator: Mansoor, Zara, Gawlik, Dale E., Office of Undergraduate Research and Inquiry
Abstract/Description: The Florida apple snail (Pomacea paludosa) is found in tropical/subtropical freshwater ecosystems climate (Cordeiro & Perez, 2011). The Florida apple snail is of special management interest because survival of the endangered Snail Kite (Rostrhamus sociabilis plumbeus) depends on a healthy populations of apple snails. Results of this study show Florida apple snails occur independently of habitat type (slough, prairie etc.), which should indicate abundant foraging habitats available to Snail...
Show moreThe Florida apple snail (Pomacea paludosa) is found in tropical/subtropical freshwater ecosystems climate (Cordeiro & Perez, 2011). The Florida apple snail is of special management interest because survival of the endangered Snail Kite (Rostrhamus sociabilis plumbeus) depends on a healthy populations of apple snails. Results of this study show Florida apple snails occur independently of habitat type (slough, prairie etc.), which should indicate abundant foraging habitats available to Snail Kites. However, Snail Kites show preferences for specific foraging habitats, which suggests that they are more restricted in available habitat than what snail habitat use would suggest.
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Date Issued: 2016
PURL: http://purl.flvc.org/fau/fd/FA00005585
Subject Headings: College students --Research --United States.
Format: Document (PDF)

Title: Linking Dynamic Habitat Selection with Wading Bird Foraging Distributions across Resource Gradients.
Creator: Beerens, James M., Noonburg, Erik G., Gawlik, Dale E., Gao, Chang-Qing
Date Issued: 2015-06-24
PURL: http://purl.flvc.org/fau/fd/FAUIR000142
Format: Citation

Title: Mechanisms That Generate Resource Pulses in a Fluctuating Wetland.
Creator: Botson, Bryan A., Gawlik, Dale E., Trexler, Joel C., Hewitt, Judi
Date Issued: 2016-07-22
PURL: http://purl.flvc.org/fau/fd/FAUIR000092
Format: Citation

Title: Physiological Condition of Juvenile Wading Birds in Relation to Multiple Landscape Stressors in the Florida Everglades: Effects of Hydrology, Prey Availability, and Mercury Bioaccumulation.
Creator: Herring, Garth, Eagles-Smith, Collin A., Gawlik, Dale E., Beerens, James M., Ackerman, Joshua T., Gao, Chang-Qing
Abstract/Description: The physiological condition of juvenile birds can be influenced by multiple ecological stressors, and few studies have concurrently considered the effects of environmental contaminants in combination with ecological attributes that can influence foraging conditions and prey availability. Using three temporally distinct indices of physiological condition, we compared the physiological response of nestling great egrets (Ardea alba) and white ibises (Eudocimus albus) to changing prey...
Show moreThe physiological condition of juvenile birds can be influenced by multiple ecological stressors, and few studies have concurrently considered the effects of environmental contaminants in combination with ecological attributes that can influence foraging conditions and prey availability. Using three temporally distinct indices of physiological condition, we compared the physiological response of nestling great egrets (Ardea alba) and white ibises (Eudocimus albus) to changing prey availability, hydrology (water depth, recession rate), and mercury exposure in the Florida Everglades. We found that the physiological response of chicks varied between species and among environmental variables. Chick body condition (shortterm index) and fecal corticosterone levels (medium-term) were influenced by wetland water depth, prey availability, region, and age, but not by mercury contamination. However, mercury exposure did influence heat shock protein 70 (HSP70) in egret chicks, indicating a longer-term physiological response to contamination. Our results indicate that the physiological condition of egret and ibis chicks were influenced by several environmental stressors, and the time frame of the effect may depend on the specialized foraging behavior of the adults provisioning the chicks.
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Date Issued: 2014-09-03
PURL: http://purl.flvc.org/fau/fd/FAUIR000064
Format: Citation

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)

Title: Wading bird use of geographically isolated wetlands in the southeastern U.S. Coastal Plain.
Creator: Herteux, Camille E., Gawlik, Dale E., Smith, Lora L., Florida Atlantic University, Charles E. Schmidt College of Science, Department of Biological Sciences
Abstract/Description: Geographically isolated wetlands (GIWs) within the southeastern U.S. Coastal Plain have been increasingly recognized for their importance in providing ecosystem services. These wetlands serve as valuable foraging and breeding habitat for wetland-dependent species, including wading birds. I quantified wading bird presence in GIWs in southwestern Georgia and determined the relative importance of factors influencing their use of these wetlands. I also examined the diet of a nesting colony of...
Show moreGeographically isolated wetlands (GIWs) within the southeastern U.S. Coastal Plain have been increasingly recognized for their importance in providing ecosystem services. These wetlands serve as valuable foraging and breeding habitat for wetland-dependent species, including wading birds. I quantified wading bird presence in GIWs in southwestern Georgia and determined the relative importance of factors influencing their use of these wetlands. I also examined the diet of a nesting colony of Little Blue Herons; a species experiencing population declines throughout most of the Southeast. I found that wetland-specific parameters were important factors in predicting wading bird use of GIWs, and wading birds utilized agricultural and natural wetlands differently depending on hydrological seasonality. Little Blue Herons were primarily consuming large anurans and anuran larvae, which are characteristic of agriculturally modified wetlands. The seasonal process of receding water levels in GIWs and subsequent concentration of
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Date Issued: 2018
PURL: http://purl.flvc.org/fau/fd/FA00013012
Subject Headings: Wetlands--Georgia, Wading birds, Herons--Ecology
Format: Document (PDF)

Title: An Analysis of the Demography and Habitat Usage of Roatan's Spiny-tailed Iguana, Ctenosaura oedirhina.
Creator: Campbell, Ashley B., Maple, Terry, Gawlik, Dale E., Florida Atlantic University, Charles E. Schmidt College of Science, Department of Psychology
Abstract/Description: The Roatan Spiny-tailed Iguana (Ctenosaura oedirhina) is endemic to the 146-km2 island of Roatn, Honduras. Harvesting for consumption, fragmentation of habitat, and predation by domestic animals threaten this lizard. It is currently listed as Endangered by the International Union for Conservation of Nature (IUCN), as threatened by the Honduran government, and is on Appendix II of the Convention on International Trade in Endangered Species (CITES). This species has been geographically...
Show moreThe Roatan Spiny-tailed Iguana (Ctenosaura oedirhina) is endemic to the 146-km2 island of Roatn, Honduras. Harvesting for consumption, fragmentation of habitat, and predation by domestic animals threaten this lizard. It is currently listed as Endangered by the International Union for Conservation of Nature (IUCN), as threatened by the Honduran government, and is on Appendix II of the Convention on International Trade in Endangered Species (CITES). This species has been geographically fragmented and genetically isolated into small subpopulations that are declining in density. With data gathered from use/availability surveys, resource selection functions were used to identify habitats and environmental variables associated with their presence. Results indicate that protection from harvesting is the most important factor in determining their distribution. These high-density populations are currently restricted to ~0.6 km2. Organisms living in small, isolated populations with very restricted ranges are at higher risk of extirpation due to various direct and indirect forces. Mark-recapture-resight surveys and distance sampling have been used to monitor the populations since 2010 and 2012 respectively. The data show that the high-density populations are declining. The current population size is estimated to be 4130-4860 individuals in 2015. A population viability analysis (PVA) was conducted to identify the most pressing threats and specific life history traits that are affecting this decline. The analysis estimates that if current trends persist, the species will be extinct in the wild in less than ten years. Adult mortality is a main factor and female mortality specifically characterizes this decline. In order for this species to persist over the next fifty years, adult mortality needs to be reduced by more than 50%. A lack of enforcement of the current laws results in the persistence of the main threat, poaching for consumption, thus altering the species distribution and causing high adult mortality. This is complicated by social customs and a lack of post primary education. Management changes could mitigate this threat and slow the population decline. Recommendations include an education campaign on the island, increased enforcement of the current laws, and breeding of C. oedirhina in situ and ex situ for release into the wild.
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Date Issued: 2015
PURL: http://purl.flvc.org/fau/fd/FA00004486, http://purl.flvc.org/fau/fd/FA00004486
Subject Headings: Adaptation (Biology), Conservation biology -- Honduras -- Roatán Island, Iguanas -- Black spiny tailed -- Honduras -- Roatán Island -- Habitat., Roatán Island (Honduras) -- Ecology
Format: Document (PDF)

Title: A biological mechanism for enhanced wading bird foraging patches in seasonally-pulsed wetlands.
Creator: Faughnan, Thomas J., Gawlik, Dale E., Florida Atlantic University, Charles E. Schmidt College of Science, Center for Environmental Studies
Abstract/Description: In tropical wetlands, breeding wading birds rely on concentrations of aquatic fauna during the dry season to meet increased energetic demands. Wetland microtopography increases aquatic fauna concentration levels. Crocodilians modify the landscape creating deep-water refugia but their role as a mechanism for aquatic fauna concentration is unknown. I sampled alligator (Alligator mississippiensis) abundance and slough microtopography to examine correlation between the two measures. Despite...
Show moreIn tropical wetlands, breeding wading birds rely on concentrations of aquatic fauna during the dry season to meet increased energetic demands. Wetland microtopography increases aquatic fauna concentration levels. Crocodilians modify the landscape creating deep-water refugia but their role as a mechanism for aquatic fauna concentration is unknown. I sampled alligator (Alligator mississippiensis) abundance and slough microtopography to examine correlation between the two measures. Despite increased microtopography in high alligator use sloughs, the differences were not significant. Using an in situ experimental approach, I quantified the magnitude, timing, and spatial extent of aquatic fauna concentrations within simulated alligator depressions and the surrounding marsh. Aquatic fauna density and biomass were greater within simulated depressions, thus enhancing wading bird foraging habitat. Further understanding the mechanisms creating microtopography, thus enhancing wading bird habitat, is critical to facilitate restoration and prevent declines of wading bird populations in seasonally pulsed wetlands worldwide.
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Date Issued: 2018
PURL: http://purl.flvc.org/fau/fd/FA00013060
Subject Headings: Wading birds., Wetland ecology., American alligator.
Format: Document (PDF)

Title: Diet and Nesting Habitat of Wading Birds in a Shallow, Eutrophic Lake.
Creator: May, Jenna C., Gawlik, Dale E., Florida Atlantic University, Charles E. Schmidt College of Science, Department of Biological Sciences
Abstract/Description: Avian reproductive success varies depending on environmental conditions, degree of predation, location, and food availability. I examined food availability and nesting habitat of wading birds in South Florida. Evaluating prey availability and prey used by two small heron species demonstrated the ability for small herons to maintain consistent diets through fluctuating environmental conditions, within and across different wetland types. Small herons may be able to cope with environmental...
Show moreAvian reproductive success varies depending on environmental conditions, degree of predation, location, and food availability. I examined food availability and nesting habitat of wading birds in South Florida. Evaluating prey availability and prey used by two small heron species demonstrated the ability for small herons to maintain consistent diets through fluctuating environmental conditions, within and across different wetland types. Small herons may be able to cope with environmental changes by altering foraging locations and strategies. Regarding nesting habitat, man-made sites may provide habitat comparable to natural sites, at least in the short-term. The nest’s position can influence its susceptibility to increased temperatures and predators, particularly for. Climatic conditions such as rainfall can also impact nesting success by altering foraging conditions and fish behavior. Understanding the effects of hydrologic regimes on biota can have practical applications since ecosystems around the world share similar problems with competing demands for resources, and there is a concern for how use can affect the quality of the resource.
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Date Issued: 2018
PURL: http://purl.flvc.org/fau/fd/FA00013087
Subject Headings: Wading birds., Herons--Ecology., Okeechobee, Lake (Fla.)
Format: Document (PDF)

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)

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)

Title: Effect of diet differences and non-native prey consumption on the productivity of small herons.
Creator: Jackson, Ashley Elizabeth, Gawlik, Dale E., Florida Atlantic University, Charles E. Schmidt College of Science, Center for Environmental Studies
Abstract/Description: Little Blue Herons, Snowy Egrets, and Tricolored Herons that nest in the Everglades have declined sharply over the past decade, due in part to food resource limitations. Here, I examined the diet of small herons to determine how prey characteristics affected the fitness of small herons in the highly modified Florida Everglades. Analysis of these diet differences showed birds nesting in 2017, a hydrologically dryer-than average year, and a more taxonomically varied diet were associated with...
Show moreLittle Blue Herons, Snowy Egrets, and Tricolored Herons that nest in the Everglades have declined sharply over the past decade, due in part to food resource limitations. Here, I examined the diet of small herons to determine how prey characteristics affected the fitness of small herons in the highly modified Florida Everglades. Analysis of these diet differences showed birds nesting in 2017, a hydrologically dryer-than average year, and a more taxonomically varied diet were associated with nest success and improved body condition of nestlings. Over half (51%) of the fish biomass Little Blue Herons consumed were non-native species, compared to 14% and 19% non-native fish biomass consumed by Snowy Egrets and Tricolored Herons, respectively. Surprisingly, <7% of fish biomass available in the Everglades were comprised of non-native fish species, suggesting that small herons, and Little Blue Herons in particular, may be using alternative foraging habitats, to supplement their dietary needs.
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Date Issued: 2018
PURL: http://purl.flvc.org/fau/fd/FA00013072
Subject Headings: Herons, Florida--Everglades., Herons--Ecology.
Format: Document (PDF)

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)

Title: Wading bird prey production and prey selection in a dynamic wetland.
Creator: Klassen, Jessica A., Gawlik, Dale E., Florida Atlantic University, Charles E. Schmidt College of Science, Department of Biological Sciences
Abstract/Description: Anthropogenic impacts, such as habitat destruction and spread of exotic species, are contributing to the sixth major extinction event in Earth’s history. To develop effective management and conservation plans, it is important to understand the ecological drivers of at-risk populations, assess the ability of a population to adapt to environmental change, and develop research methods for long-term ecosystem monitoring. I used wading birds nesting in the Florida Everglades, USA as a model system...
Show moreAnthropogenic impacts, such as habitat destruction and spread of exotic species, are contributing to the sixth major extinction event in Earth’s history. To develop effective management and conservation plans, it is important to understand the ecological drivers of at-risk populations, assess the ability of a population to adapt to environmental change, and develop research methods for long-term ecosystem monitoring. I used wading birds nesting in the Florida Everglades, USA as a model system to address the challenges of managing and monitoring populations within an ecosystem greatly impacted by anthropogenic activities. Specifically, my project investigated 1) the prey selection of wading bird species, and the role of prey and foraging habitat availability on annual nesting numbers, 2) the ability of using diet change to predict species adaptability to a rapidly changing environment, and 3) the use of sensory data to provide low-cost, long-term monitoring of dynamic wetlands. I found that tricolored herons, snowy egrets, and little blue herons consumed marsh fish larger than those generally available across the landscape. Additionally, number of nests initiated by tricolored herons, snowy egrets, and little blue herons was strongly correlated with the annual densities of large fish available within the Everglades landscape. Conversely, number of nests initiated by wood storks, great egrets, and white ibises was more correlated with the amount of foraging habitat availability across the nesting season. Wood stork diets changed considerably since the 1960’s, consisting of mainly sunfish and exotic fish as opposed to marsh fishes dominant in historical diet studies. Storks also consumed more exotic fish species than they did historically. This diet plasticity and the species’ ability to exploit anthropogenic habitats may be conducive to maintaining population viability as storks experience widespread human-induced changes to their habitat. Sensory-only data models generated complementary results to models that used site-specific field data. Additionally, sensory-only models were able to detect different responses between size classes of fish to the processes that increase their concentrations in drying pools. However, the degree to which sensory variables were able to fit species data was dependent upon the ability of sensors to measure species-specific population drivers and the scale at which sensors can measure environmental change.
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Date Issued: 2016
PURL: http://purl.flvc.org/fau/fd/FA00004716
Subject Headings: Charadriiformes -- Habitat -- Florida -- Everglades, Ciconiiformes -- Habitat -- Florida -- Everglades, Everglades National Park (Fla.) -- Environmental conditions, Predation (Biology), Wetland ecology, Wildlife conservation
Format: Document (PDF)

Title: The Associations of Little Blue Heron Prey and Vegetation Communities in Two Subtropical Coastal Ecosystems.
Creator: Kohler, Emilie R., Gawlik, Dale E., Florida Atlantic University, Charles E. Schmidt College of Science, Department of Biological Sciences
Abstract/Description: Shallow water availability coupled with anthropogenic degradation of seagrass beds limits wading bird food resources in dynamic coastal ecosystems. Identifying prey species critical to wading bird reproductive success and the environmental drivers of key prey species abundance is important for understanding how environmental stressors influence prey and change the quality of foraging patches. Little Blue Herons (Egretta caerulea) are reportedly generalists eating insects, crustaceans, and...
Show moreShallow water availability coupled with anthropogenic degradation of seagrass beds limits wading bird food resources in dynamic coastal ecosystems. Identifying prey species critical to wading bird reproductive success and the environmental drivers of key prey species abundance is important for understanding how environmental stressors influence prey and change the quality of foraging patches. Little Blue Herons (Egretta caerulea) are reportedly generalists eating insects, crustaceans, and fish; however, the proportions of prey items in the diet may shift spatially and temporally from freshwater to marine systems during breeding and non-breeding periods. I investigated prey selection by Little Blue Herons in Florida at the Great White Heron National Wildlife Refuge and the western Florida Bay, during 2016 and 2017 breeding seasons by investigating prey availability at low-tide locations along mudflats compared to stomach regurgitate samples collected from Little Blue Heron chicks 1 to 4 weeks old. Little Blue Herons selected Gulf toadfish (Opsanus beta) and prawns (Farfantepenaeus spp.) from the estuarine environment, but also consumed terrestrial prey (e.g. tree crabs) suggesting Little Blue Heron foraging habitat is not restricted to tidal flats. Additionally, these results support the characterization of Little Blue Herons as a generalist. After identifying important prey species, I modeled the associations of selected prey species with submerged aquatic vegetation density and abiotic variables to better understand habitat preferences and important habitat characteristics that drive prey density. Models support total seagrass density and algal density as having the greatest effect on prey selected by Little Blue Herons. Prawn density has a strong positive association with seagrass density. Gulf toadfish (Opsanus beta) and prawns (Farfantepenaeus spp.) had strong positive association with algae while pipefish (Syngnathidae) had a strong negative association with algae suggesting algae density in seagrass meadows should be considered when assessing the quality of seagrass meadows for Little Blue Heron prey and habitat suitability. My results varied from previous studies where prawns and gulf toadfish were associated with specific seagrass species. Therefore, some Little Blue Heron prey species in south Florida may not be affected by changes in submerged aquatic vegetation community composition if submerged aquatic vegetation densities remain constant. Studies are needed that clarify the complex interactions between prey and specific habitat metrics to validate the strength of landscape scale drivers of wading bird prey densities in dynamic coastal ecosystems and to determine how these communities will respond to anthropogenic environmental change.
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Date Issued: 2018
PURL: http://purl.flvc.org/fau/fd/FA00013156
Subject Headings: Herons--Ecology, Egretta, Great White Heron National Wildlife Refuge (Fla), Florida Bay (Fla), Coastal ecology--Florida
Format: Document (PDF)

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Gawlik, Dale E. (29)	+ -
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