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Dietary niche relationships of white ibis, tricolored heron and snowy egret nestlings in the northern Everglades
Title
Dietary niche relationships of white ibis, tricolored heron and snowy egret nestlings in the northern Everglades.
Creator
Boyle, Robin A., Charles E. Schmidt College of Science, Department of Biological Sciences
Abstract/Description
Food availability is the primary factor affecting the reproductive success in many species of birds. Diet composition can indicate diet quality, habitat use and niche requirements for breeding birds and may be variable across short and long-term time scales. Identifying primary prey types of nesting wading birds is important for the hydrologic restoration of wetlands. I collected nestling boluses during the 2008 and 2009 nesting seasons from three species of wading birds that nest in the...
Show moreFood availability is the primary factor affecting the reproductive success in many species of birds. Diet composition can indicate diet quality, habitat use and niche requirements for breeding birds and may be variable across short and long-term time scales. Identifying primary prey types of nesting wading birds is important for the hydrologic restoration of wetlands. I collected nestling boluses during the 2008 and 2009 nesting seasons from three species of wading birds that nest in the northern Everglades: White Ibis, Tricolored Herons and Snowy Egrets. White Ibis bolus composition was dominated by crayfish in both years, but exhibited some variation with landscape water depth in 2009; fish use was greatest when the wetland landscape was relatively dry. In contrast, the prey of Tricolored Herons and Snowy Egrets were primarily fish and their respective diets did not differ from one another in either fish species composition or size structure.
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Date Issued
2010
PURL
http://purl.flvc.org/FAU/2953207
Subject Headings
Wetland ecology, Bird populations, Water birds
Format
Document (PDF)
Constraints of landscape level prey availability on physiological condition and productivity of great egrets and white ibises in the Florida Everglades
Title
Constraints of landscape level prey availability on physiological condition and productivity of great egrets and white ibises in the Florida Everglades.
Creator
Herring, Garth, Florida Atlantic University, Charles E. Schmidt College of Science, Department of Biological Sciences
Abstract/Description
Life history strategy suggests long lived bird species will adjust their nesting effort according to current conditions, balancing the costs of reproduction with their long-term needs for survival and future reproduction. The habitat conditions that produce these responses may differ between species, even within the same ecosystem, producing different nesting and population trends. I traced the pathway by which food availability influences the physiological condition of pre-breeding great...
Show moreLife history strategy suggests long lived bird species will adjust their nesting effort according to current conditions, balancing the costs of reproduction with their long-term needs for survival and future reproduction. The habitat conditions that produce these responses may differ between species, even within the same ecosystem, producing different nesting and population trends. I traced the pathway by which food availability influences the physiological condition of pre-breeding great egrets and white ibises through to reproductive measures, and the physiological condition of chicks. I focused on these two species with contrasting foraging strategies, in relation to foraging and habitat conditions to maximize the likelihood of application of these results to other wading bird species. Experimental food supplementation and physiology research on white ibis chicks demonstrated that in years with low prey availability white ibis were food limited, with increased levels of stress protein 60 and fecal corticosterone. This is the first study to demonstrate experimentally the response of stress protein 60 to changing levels of food availability. During a year with low prey availability (2007) white ibis adults and chick physiological condition was lower than that of great egrets. During the same year, fledging success was lower for both species (20% for white ibis versus 27% for great egret) but the magnitude of the decrease was particularly severe for the white ibis (76% decline versus 66% decline for the great egret). Results suggest white ibises modify their clutch size during years with poor habitat in accordance with life history traits of a long-lived species, whereas great egrets maintained their clutch size during years with poor habitat., Increasing recession rates, hydrological reversals, and prey densities influenced white ibis, whereas great egrets were most influenced by prey densities and recession rates, with no effect of hydrological reversal. During the same year, fledging success was lower for both species (20% for white ibis versus 27% for great egret) but the magnitude of the decrease was particularly severe for the white ibis (76% decline versus 66% decline for the great egret). Results suggest white ibises modify their clutch size during years with poor habitat in accordance with life history traits of a long-lived species, whereas great egrets maintained their clutch size during years with poor habitat. Increasing recession rates, hydrological reversals, and prey densities influenced white ibis, whereas great egrets were most influenced by prey densities and recession rates, with no effect of hydrological reversals. This study is the first to make the link between landscape hydrology patterns, prey availability, and responses in wading bird nesting. These linkages provide critical insight into how species' nesting patterns could differ given the same time and spatial constraints and how that may be related to long-term nesting trends. This knowledge could ultimately lead to novel predictions about population and community patterns of wetland birds.
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Date Issued
2008
PURL
http://purl.flvc.org/FAU/77643
Subject Headings
Bird populations, Water birds, Wetland ecology
Format
Document (PDF)
Hierarchical resource selection and movement of two wading bird species with divergent foraging strategies in the Everglades
Title
Hierarchical resource selection and movement of two wading bird species with divergent foraging strategies in the Everglades.
Creator
Beerens, James M., Charles E. Schmidt College of Science, Department of Biological Sciences
Abstract/Description
Seasonal variation in food availability is one of the primary limitations to avian populations, particularly during the breeding season. However, the behavioral responses between species may differ based on foraging strategies. I examined the influence of food availability on landscape-level habitat selection, patch-level habitat selection, and movements of two wading bird species with divergent foraging strategies, the Great Egret and White Ibis. On a landscape scale, there appeared to be a...
Show moreSeasonal variation in food availability is one of the primary limitations to avian populations, particularly during the breeding season. However, the behavioral responses between species may differ based on foraging strategies. I examined the influence of food availability on landscape-level habitat selection, patch-level habitat selection, and movements of two wading bird species with divergent foraging strategies, the Great Egret and White Ibis. On a landscape scale, there appeared to be a relationship among resource availability, the temporal scale of the independent variable, and whether the response was similar or different between species. At the patch level, results demonstrated a relationship between resource availability and the spatial scale of the independent variables selected by birds. Species movements were consistent with the differing strategies. This study is the first to make the link between landscape hydrology patterns, prey availability, and responses in wading bird habitat selection at multiple spatial scales.
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Date Issued
2008
PURL
http://purl.flvc.org/FAU/172667
Subject Headings
Water birds, Habitat, Habitat selection, Bird populations, Wetland ecology
Format
Document (PDF)
Factors Affecting Wading Bird Prey Concentrations in the Everglades During the Dry Season
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)
Characteristics Affecting Prey Vulnerability and Avian Habitat Selection in the Florida Everglades
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)
Foraging Habitat Modeling and Nesting Ecology of Wood Storks in Everglades National Park
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)
Modeling Long-Term Changes, 1958-2011, In The Reproduction And Territory Dynamics Of Bald Eagles Of Florida Bay, Southern Coastal Everglades
Title
Modeling Long-Term Changes, 1958-2011, In The Reproduction And Territory Dynamics Of Bald Eagles Of Florida Bay, Southern Coastal Everglades.
Creator
Bosley, Jason W., Noonburg, Erik G., Florida Atlantic University, Charles E. Schmidt College of Science, Department of Biological Sciences
Abstract/Description
As top-level piscivores, Bald Eagles are a compelling subject for the study of territory dynamics and are highly representative of the distinctive suite of avian species that occupy Florida Bay. Despite successful recovery of Bald Eagles (Haliaeetus leuocephalus) throughout the species range, the population breeding within Florida Bay has not mirrored this trend. Beginning in the late 1980s, Florida Bay has suffered in its capacity to support species diversity and abundance as a result of...
Show moreAs top-level piscivores, Bald Eagles are a compelling subject for the study of territory dynamics and are highly representative of the distinctive suite of avian species that occupy Florida Bay. Despite successful recovery of Bald Eagles (Haliaeetus leuocephalus) throughout the species range, the population breeding within Florida Bay has not mirrored this trend. Beginning in the late 1980s, Florida Bay has suffered in its capacity to support species diversity and abundance as a result of extreme changes in hydrology related to altered flows of incoming freshwater. In fact, Bald Eagle territory use in Florida Bay has declined by as much as 43% as year to year variation and sensitivity to transitions between territory states have increased. Florida Bay’s populations of other large, conspicuous fish-eating birds, including Ospreys, Great White Herons, Roseate Spoonbills, and Reddish Egrets each exhibit a similar pattern of decline. The effects of environmental degradation throughout Florida Bay are magnified at higher trophic levels. The negative trend in territory occupancy is most pronounced in southeast Florida Bay whereas effects on territory occupancy in the northwest are minimal. The presence of spatial patterns in territory occupancy, despite regionally available breeding birds, suggests that individuals are evaluating differences in habitat quality for which certain territories are no longer considered viable. Building on our current understanding of the health of this population of Bald Eagles, we have successfully implemented modeling approaches that identify key territory breeding decisions. Loss of early breeding season activity (occupied and active territories) despite maintaining high breeding success indicates that changes in territory dynamics are the result of a failure to breed and not a reproductive failure. As such, future conservation actions should promote early breeding season activity (decisions by breeding pairs to initiate nesting) in areas of Florida Bay that were historically occupied but are now abandoned.
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Date Issued
2017
PURL
http://purl.flvc.org/fau/fd/FA00004859, http://purl.flvc.org/fau/fd/FA00004859
Subject Headings
Bald eagle--Everglades National Park--Florida Bay--Geographical distribution., Bald eagle--Breeding--Everglades National Park--Florida Bay., Bald eagle--Habitat--Everglades National Park--Florida Bay., Bird populations--Conservation--Florida.
Format
Document (PDF)