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- Title
- RESPONSES OF WOOD STORKS TO HUMAN-INDUCED LANDSCAPE CHANGE IN SOUTH FLORIDA.
- Creator
- Evans, Betsy A., Gawlik, Dale E., Florida Atlantic University, Department of Biological Sciences, Charles E. Schmidt College of Science
- Abstract/Description
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There is a strong conservation need to understand traits of native species that adapt to urban environments, but results have been equivocal. Wetland birds have shown a strong phylogenetic signal towards urban tolerance; however, these species have largely been ignored in urban studies. I used Wood Storks (Mycteria americana) to determine how a wetland species of conservation concern responded to human-induced landscape change in South Florida. Specifically, my study investigated 1) resource...
Show moreThere is a strong conservation need to understand traits of native species that adapt to urban environments, but results have been equivocal. Wetland birds have shown a strong phylogenetic signal towards urban tolerance; however, these species have largely been ignored in urban studies. I used Wood Storks (Mycteria americana) to determine how a wetland species of conservation concern responded to human-induced landscape change in South Florida. Specifically, my study investigated 1) resource selection of storks in roadway corridors, 2) factors influencing stork prey biomass in roadside created wetlands, 3) dietary flexibility of storks in response to human-induced landscape change, and 4) the impact of urban food subsidies on natural food limitations and stork productivity. I found that storks preferred canals and roadway corridors within the urban landscape. At a finer scale, storks selected for more natural wetland vegetation even within the urban landscape cover type. These results suggest that roadway corridors even within a highly urbanized area may provide adequate foraging habitat for storks. Factors influencing stork prey biomass in roadside created wetlands varied depending on created wetland type. I found that landscape-level vegetation and the physical properties of a created wetland were more influential in permanently inundated created wetlands whereas local-scale vegetation and hydrologic conditions were most influential in ephemeral created wetlands. Storks also selected prey that were more similar to the larger-bodied fishes in created wetlands than the smaller fishes in natural wetlands. Urban nesting storks selected prey that were more characteristic of created wetlands whereas storks nesting in natural wetlands selected prey that was more characteristic of prey found in natural wetlands. These results suggested that storks may have behavioral plasticity in foraging habitat and prey selection to adapt to some degree of human-induced rapid environmental change. Additionally, storks nesting in both urban and natural wetlands had narrow diet breadths and high productivity during optimal natural wetland conditions; however, during suboptimal natural conditions, urban stork diet expanded to include anthropogenic items, leading to increased productivity. Overall, this research provides a mechanistic understanding of how a wetland species persists, and even thrives, in an urban environment.
Show less - Date Issued
- 2020
- PURL
- http://purl.flvc.org/fau/fd/FA00013554
- Subject Headings
- Wood stork, Mycteria americana, Human influence on nature, Nature conservation--Florida, Urban environment
- Format
- Document (PDF)
- Title
- REPRODUCTIVE RESPONSES OF THREE HERON SPECIES TO VARIABLE FORAGING CONDITIONS AND NESTING ISLAND TYPE IN A MANAGED LAKE ECOSYSTEM.
- Creator
- Evans, Jacquelyn D., Gawlik, Dale E., Florida Atlantic University, Department of Biological Sciences, Charles E. Schmidt College of Science
- Abstract/Description
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The relationship between water-level fluctuations and wading bird nest numbers and nesting location is well documented, yet species-specific reproductive responses of wading birds to environmental drivers and nesting habitat type is poorly understood. Here, I compared the reproductive responses of two ecologically similar species, Snowy Egret and Tricolored Heron, to foraging conditions influenced by water management and examined the effect of nestling island type on the reproductive success...
Show moreThe relationship between water-level fluctuations and wading bird nest numbers and nesting location is well documented, yet species-specific reproductive responses of wading birds to environmental drivers and nesting habitat type is poorly understood. Here, I compared the reproductive responses of two ecologically similar species, Snowy Egret and Tricolored Heron, to foraging conditions influenced by water management and examined the effect of nestling island type on the reproductive success of three wading bird species. Reproductive responses to foraging conditions were broadly similar between Snowy Egrets and Tricolored Herons, however this study revealed specific-specific differences that could lead to different population dynamics in response to management over the long-term. I also found that these two species had lower productivity at spoil islands than marsh colonies, whereas Great Egret productivity did not vary by colony type. This study demonstrates the importance of establishing species-species relationships between productivity and environmental conditions
Show less - Date Issued
- 2020
- PURL
- http://purl.flvc.org/fau/fd/FA00013550
- Subject Headings
- Herons--Ecology, Reproduction, Nesting behavior, Okeechobee, Lake (Fla), Species
- Format
- Document (PDF)
- Title
- Quantifying wading bird resource selection and nesting effort: a tool for the restoration of pulsed ecosystems.
- Creator
- Petersen, Michelle L., Gawlik, Dale E., Florida Atlantic University, Charles E. Schmidt College of Science, Department of Biological Sciences
- Abstract/Description
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Understanding the link between indicator species and their environment is imperative to managing and conserving anthropogenically-altered ecosystems. Seasonally-pulsed wetlands are uniquely complex ecosystem where water-level fluctuations shape trophic interactions. Anthropogenic manipulation of water-level fluctuation threatens the integrity of these systems worldwide. Wading birds, a group of species sensitive to landuse changes and fluctuating habitat conditions, serve as important...
Show moreUnderstanding the link between indicator species and their environment is imperative to managing and conserving anthropogenically-altered ecosystems. Seasonally-pulsed wetlands are uniquely complex ecosystem where water-level fluctuations shape trophic interactions. Anthropogenic manipulation of water-level fluctuation threatens the integrity of these systems worldwide. Wading birds, a group of species sensitive to landuse changes and fluctuating habitat conditions, serve as important indicators for wetland health. I used wading birds in the Everglades, as a model system to address the challenges of environmental restoration within an ecosystem heavily impacted by anthropogenic activities. Specifically, I 1) identified the nesting response of Great Egret (Ardea alba), White Ibis (Eudocimus albus), and Wood Stork (Mycteria americana) to hydrologically-mediated changes in food availability and 2) quantified spatiotemporal foraging-habitat selection of Great Egrets, White Ibis, and Wood Storks to fluctuating hydrologic conditions. Collectively, model selection results suggest food availability, generated through dynamic hydrological conditions, is a strong predictor of the abundance of nesting birds in a given year. Great egret and white ibis produce the highest nests numbers in years when the frequency of days of rising water is low. Wood stork nest numbers are the highest in years with high prey production coupled with continuous prey availability. My study of resource selection indicated wading birds select foraging sites based on similar hydrologic parameters, but the response varies by species. Wood storks are more likely to forage in shallow cells (< 10 cm) drying with high recession rates (0.5-1.5 cm/day), and long time since last drydown (600 days). White ibises selected foraging cells with relatively shallow water depths (0-15 cm), intermediate recession rates (0.5-1.0 cm/day), and long time since drydown (600 days). Great egrets selected foraging cells with a wider range of water depths (0-20 cm) where recession rates were lower (0.5 cm/day). All species are more likely to forage in cells where water has not increased by more than 3 cm in the previous two weeks. These differences in resource selections correspond to morphological and behavioral differences in the species, whereby wood storks were more constrained hydrologically and would be more affected by water-level manipulation.
Show less - Date Issued
- 2017
- PURL
- http://purl.flvc.org/fau/fd/FA00004852
- Subject Headings
- Wetland biodiversity conservation--Florida--Everglades., Wetland conservation., Water birds., Wood stork., White ibis., Egretta alba.
- Format
- Document (PDF)
- Title
- MONITORING WADING BIRD COLONIES USING ACOUSTIC SAMPLING AND REGIONAL SHIFTS IN WADING BIRD NEST ABUNDANCES IN A PULSED WETLAND SYSTEM.
- Creator
- Larson, Rachel C., Gawlik, Dale E., Florida Atlantic University, Department of Biological Sciences, Charles E. Schmidt College of Science
- Abstract/Description
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Wetland loss and degradation have led to the development of restoration programs worldwide, many of which monitor wading bird populations as indicators of wetland quality. Therefore, efficient, standardized monitoring is integral to restoration progress. I tested the use of passive acoustic monitoring to estimate nest abundances and provisioning rates in wading bird colonies and examined regional nesting dynamics in the Florida Everglades, where a long monitoring record enables analysis of...
Show moreWetland loss and degradation have led to the development of restoration programs worldwide, many of which monitor wading bird populations as indicators of wetland quality. Therefore, efficient, standardized monitoring is integral to restoration progress. I tested the use of passive acoustic monitoring to estimate nest abundances and provisioning rates in wading bird colonies and examined regional nesting dynamics in the Florida Everglades, where a long monitoring record enables analysis of nesting patterns relative to hydrologic changes. I found that call rates can serve as indices of colony nest abundances and begging call rate and timing are indicative of provisioning events. Nesting dynamics suggested that resource availability is asynchronous between regions of the Everglades, but the degree of asynchrony varies with species. The conclusions of this study will facilitate the long-term monitoring of wading bird nesting trends, which are important measures of wetland restoration in Florida and worldwide.
Show less - Date Issued
- 2021
- PURL
- http://purl.flvc.org/fau/fd/FA00013771
- Subject Headings
- Wetland restoration, Wading birds, Everglades (Fla.), Acoustics
- Format
- Document (PDF)
- Title
- INFLUENCE OF HYDROLOGICAL VARIATION ON WADING BIRD DIETS AND REPRODUCTION IN A LACUSTRINE WETLAND.
- Creator
- Essian, David A., Gawlik, Dale E., Florida Atlantic University, Department of Biological Sciences, Charles E. Schmidt College of Science
- Abstract/Description
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Wetlandscape topography creates spatial variation in hydroperiod, which in turn creates spatial variation in biotic communities. Such spatiotemporal variation occurs on a large scale in some of the most productive wetlands in the world, including those of south Florida, U.S.A. Wading birds (Pelicaniformes and Ciconiiformes) are iconic, top-level consumers of such ecosystems. Infrequent drying is necessary to maintain the primary nest substrate (Salix caroliniana), and prey availability is...
Show moreWetlandscape topography creates spatial variation in hydroperiod, which in turn creates spatial variation in biotic communities. Such spatiotemporal variation occurs on a large scale in some of the most productive wetlands in the world, including those of south Florida, U.S.A. Wading birds (Pelicaniformes and Ciconiiformes) are iconic, top-level consumers of such ecosystems. Infrequent drying is necessary to maintain the primary nest substrate (Salix caroliniana), and prey availability is regulated by production of prey biomass in the wet season and the subsequent concentration of prey biomass into shallow pools during the dry season. The goal of this dissertation was to explicitly model wading bird nest abundance and survival as functions of water-level fluctuations, which were spatially nested (i.e., the effects of water-level fluctuations that occurred over a large scale were measured separately from the effects of water-level fluctuations that occurred over a small scale). In Chapter 2, I modeled colony-specific effects of wetlandscape water level fluctuations on wading bird nest abundance. Modeling the response at the colony level allowed the inclusion of important parameters that cannot be measured at the wetlandscape scale. For instance, each colony had its own optimal range of lake stage, which depended on local topography. I used the models to predict cumulative nest abundance under six hydrologic scenarios that were based on potential water management actions at Lake Okeechobee. I found that increasing water levels at the lake would marginally benefit the Great Egret but would substantially reduce long-term Snowy Egret and White Ibis populations. In Chapter 3, I modelled spatiotemporal distributions of fish biomass density in Lake Okeechobee’s littoral zone as a function of hierarchically nested hydrological variables. These models were consistent with the dynamic landscape connectivity model previously described in the literature. I modified the models to predict a binomial response which could then be linked to wading bird foraging threshold. The model predictions were used to estimate the number of available patch days during the breeding season, which was highly correlated with the number of nests for the great egret (Ardea alba), the snowy egret (Egretta thula), and the white ibis (Eudocimus albus). In Chapter 4, I used spatial statistics to better understand how interannual variability in resource wave patterns in the littoral zone influenced wading bird nest abundance. I found that more birds nested in years when the drying edge of the marsh moved further across the landscape. Great egret nest survival increased also, but small heron nest survival decreased. This decrease was likely because small herons continued to nest late into the season in years with longer waves, and, as with most bird species, nests that are initiated later in the season. In Chapter 5, I compiled conventional nestling diet data from 5 wading bird species sampled in 4 wetland types from 2010 to 2020 (not every wetland type was sampled in every year). This chapter provides a comprehensive, broad description of wading bird diets in south Florida, and quantifies interspecies, spatial, and interannual variation in nestling diets. By using a model-based approach to quantify the relative biomass of prey species and prey traits in nestling diets, I provide the first diet analysis that is fully reproducible across the large sympatric range of the wading bird species in the study (great egret, snowy egret, tricolored heron [Egretta tricolor], little blue heron [Egretta caerulea], and wood stork [Mycteria americana]).
Show less - Date Issued
- 2022
- PURL
- http://purl.flvc.org/fau/fd/FA00013908
- Subject Headings
- Wading birds, Wetland ecology, Okeechobee, Lake (Fla.), Lacustrine ecology, Lake ecology--Florida.
- Format
- Document (PDF)
- Title
- FORAGING ECOLOGY OF A WADING BIRD IN TIDALLY INFLUENCED HABITATS: A SEQUENTIAL MODELING FRAMEWORK.
- Creator
- Martinez, Marisa Takada, Gawlik, Dale E., Florida Atlantic University, Department of Biological Sciences, Charles E. Schmidt College of Science
- Abstract/Description
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I used empirical data to inform spatially- and temporally-explicit predictions of time-integrated habitat availability (TiHAB), quantify spatiotemporal patterns of resource selection by Little Blue Herons (Egretta caerulea), and evaluate foraging activity as function of resource availability and prey dynamics. Evaluating resource availability over time accounts for the magnitude and duration of resource change. This approach is useful for understanding mechanisms that underlie resource...
Show moreI used empirical data to inform spatially- and temporally-explicit predictions of time-integrated habitat availability (TiHAB), quantify spatiotemporal patterns of resource selection by Little Blue Herons (Egretta caerulea), and evaluate foraging activity as function of resource availability and prey dynamics. Evaluating resource availability over time accounts for the magnitude and duration of resource change. This approach is useful for understanding mechanisms that underlie resource selection in dynamic environments and for guilds that are sensitive to changes in prey availability like wading birds. I found that average TiHAB varied interannually whereby gains and losses in Little Blue Heron foraging habitat at the landscape scale (1-8 km) occurred from slight differences in annual tidal cycles otherwise imperceptible with water depth data alone. Local patterns of resource selection by Little Blue Herons were temporally consistent but spatially variable across tidally influenced environments. TiHAB was the most important habitat attribute over time and space and was superior to other environmental features and prey density as a predictor of Little Blue Heron resource selection. Foraging activity did not show a clear association with probability of resource selection, but foraging metrics were best described by changes in TiHAB consistent with changes in foraging strategy. I conclude that spatiotemporal variation in resource availability reliably predicts patterns of dynamic habitat selection and supports an energy-maximizing foraging strategy for wading birds in tidally influenced habitats. This modeling framework can be applied to quantify the spatiotemporal availability of resources in real-time or under hydrologic restoration regimes and sea level rise scenarios, and track species responses to hydrologic and other environmental fluctuations.
Show less - Date Issued
- 2022
- PURL
- http://purl.flvc.org/fau/fd/FA00013925
- Subject Headings
- Ecology, Herons, Wading birds, Ecological modelling
- Format
- Document (PDF)
- Title
- EVOLVING RESPONSE OF THE WOOD STORK (MYCTERIA AMERICANA) TO URBANIZATION AND HYDROLOGICAL CHANGE IN THE UNITED STATES.
- Creator
- Shlepr, Katherine R., Gawlik, Dale E., Milton, Sarah L., Florida Atlantic University, Department of Biological Sciences, Charles E. Schmidt College of Science
- Abstract/Description
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Urbanization and land development, climate change, pollution, the spread of invasive species, and sea level rise are unprecedented challenges that have led to 25% of avian species worldwide facing an elevated risk of extinction. Under rapidly changing environmental conditions, traditional population models are not ideal because they typically assume that demographic parameters are static in order to estimate the probability of species extinction over a chosen timeframe. This assumption...
Show moreUrbanization and land development, climate change, pollution, the spread of invasive species, and sea level rise are unprecedented challenges that have led to 25% of avian species worldwide facing an elevated risk of extinction. Under rapidly changing environmental conditions, traditional population models are not ideal because they typically assume that demographic parameters are static in order to estimate the probability of species extinction over a chosen timeframe. This assumption disregards species’ potential to adapt to environmental change; adaptations which could alter not only a species’ extinction outlook but also its legal protection status. The goal of my PhD research is to re-evaluate the risk of extinction of one threatened species, the Wood Stork (Mycteria americana), by accounting for potential adaptation in the context of planned and predicted changes in the southeastern United States. Since the 1970s, Wood Storks have shifted the timing of their breeding season, expanded their range northward and into novel habitats in urban areas, and begun consuming non-native fishes. I investigate these observations by comparing the physiology and diet of Wood Storks nesting in the historical core of their U.S. range (tree islands in the flooded Everglades marsh) with storks occupying novel habitats in urban and temperate locations. Faster growth rate, improved body condition, and increased survival by nestlings in urban areas would be evidence that colonies on the leading edge of the species’ range may be capable of sustaining growth of the whole population. In a third and final chapter, I forecast nest abundance and distribution patterns in the entirety of the U.S. range given various hydrological scenarios. Increased Wood Stork population size and stability are recovery criteria which must be met before the species can qualify for removal from the federal Endangered Species List. More broadly, understanding Wood Stork response to human development in the Everglades illuminates general patterns in avian species response to extreme changes in landscape, and could serve as a framework for proactively incorporating evolutionary potential into the framework of Endangered Species Act recovery in other species which have a high adaptive capacity.
Show less - Date Issued
- 2022
- PURL
- http://purl.flvc.org/fau/fd/FA00013916
- Subject Headings
- Wood stork, Urbanization, Adaptation (Biology), Wildlife conservation
- Format
- Document (PDF)
- Title
- The Role of Stress Proteins in the Study of Allostatic Overload in Birds: Use and Applicability to Current Studies in Avian Ecology.
- Creator
- Herring, Garth, Gawlik, Dale E.
- Abstract/Description
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Stress proteins offer a measure of stress in birds at the cellular level that are an alternative to the glucocorticoids. Stress proteins are not biased by handling stress, the increase in stress proteins lasts longer than with other measures (e.g., corticosterone), and, therefore, they may be a more appropriate measure of long-term or chronic stress. However, caution should be practiced when using stress proteins because the level of stress needed to elicit a response may be higher than with...
Show moreStress proteins offer a measure of stress in birds at the cellular level that are an alternative to the glucocorticoids. Stress proteins are not biased by handling stress, the increase in stress proteins lasts longer than with other measures (e.g., corticosterone), and, therefore, they may be a more appropriate measure of long-term or chronic stress. However, caution should be practiced when using stress proteins because the level of stress needed to elicit a response may be higher than with corticosterone. Stress proteins have only recently been used to measure the response to competition, food limitation, growth, and parasitism in birds. In other taxa, the stress proteins have been used to measure genetic stress, temperature, toxins, UV radiation, and physical activity. Stress proteins increase the options available to avian ecologists for understanding how avian species respond to changes in the environment.
Show less - Date Issued
- 2007
- PURL
- http://purl.flvc.org/fau/fd/FAUIR000071
- Format
- Citation
- Title
- Determining habitat quality for species that demonstrate dynamic habitat selection.
- Creator
- Beerens, James M., Frederick, Peter C., Noonburg, Erik G., Gawlik, Dale E.
- Date Issued
- 2015-11-19
- PURL
- http://purl.flvc.org/fau/fd/FAUIR000141
- Format
- Citation