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(1 - 8 of 8)
- 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.
Show less - Date Issued
- 2010
- PURL
- http://purl.flvc.org/FAU/2953207
- Subject Headings
- Wetland ecology, Bird populations, Water birds
- Format
- Document (PDF)
- 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
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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.
Show less - Date Issued
- 2008
- PURL
- http://purl.flvc.org/FAU/77643
- Subject Headings
- Bird populations, Water birds, Wetland ecology
- Format
- Document (PDF)
- 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.
Show less - Date Issued
- 2008
- PURL
- http://purl.flvc.org/FAU/172667
- Subject Headings
- Water birds, Habitat, Habitat selection, Bird populations, Wetland ecology
- 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.
Show less - 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.
Show less - 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
- The effects of water depth and vegetation on wading bird foraging habitat selection and foraging succes in the Everglades.
- Creator
- Lantz, Samantha., Charles E. Schmidt College of Science, Department of Biological Sciences
- Abstract/Description
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Successful foraging by avian predators is influenced largely by prey availability. In a large-scale experiment at the Loxahatchee Impoundment Landscape Assessment project within the Arthur R. Marshall Loxahatchee National Wildlife Refuge, I manipulated two components of prey availability, water depth and vegetation density (submerged aquatic vegetation and emergent vegetation), and quantified the response by wading birds in terms of foraging habitat selection and foraging success. Manly's...
Show moreSuccessful foraging by avian predators is influenced largely by prey availability. In a large-scale experiment at the Loxahatchee Impoundment Landscape Assessment project within the Arthur R. Marshall Loxahatchee National Wildlife Refuge, I manipulated two components of prey availability, water depth and vegetation density (submerged aquatic vegetation and emergent vegetation), and quantified the response by wading birds in terms of foraging habitat selection and foraging success. Manly's standardized selection index showed that birds preferred shallow water and intermediate vegetation densities. However, the treatments had little effect on either individual capture rate or efficiency. This was a consistent pattern seen across multiple experiments. Birds selected for certain habitat features but accrued little benefit in terms of foraging success. I hypothesize that birds selected sites with shallow water and intermediate vegetation densities because they anticipated higher prey densities, but they did not experience it here because I controlled for prey density.
Show less - Date Issued
- 2008
- PURL
- http://purl.flvc.org/FAU/2788592
- Subject Headings
- Water birds, Habitat, Wetland ecology, Habitat selection, Avian ecology, Wildlife management
- Format
- Document (PDF)
- 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.
Show less - 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)
- 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
-
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)
