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Physiological Condition of Juvenile Wading Birds in Relation to Multiple Landscape Stressors in the Florida Everglades: Effects of Hydrology, Prey Availability, and Mercury Bioaccumulation
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
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)
The Role of Stress Proteins in the Study of Allostatic Overload in Birds: Use and Applicability to Current Studies in Avian Ecology
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
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.
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Date Issued
2007
PURL
http://purl.flvc.org/fau/fd/FAUIR000071
Format
Citation