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.
abstract: 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 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 (short-term 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.
authors.affiliation: United States Geological Survey, Forest and Rangeland Ecosystem Science Center, Corvallis, Oregon, United States of America.
authors.forename: Garth
authors.initials: G
authors.lastname: Herring
authors.affiliation: United States Geological Survey, Forest and Rangeland Ecosystem Science Center, Corvallis, Oregon, United States of America.
authors.forename: Collin A
authors.initials: CA
authors.lastname: Eagles-Smith
authors.affiliation: Department of Biological Sciences, Florida Atlantic University, Boca Raton, Florida, United States of America.
authors.forename: Dale E
authors.initials: DE
authors.lastname: Gawlik
authors.affiliation: Department of Biological Sciences, Florida Atlantic University, Boca Raton, Florida, United States of America.
authors.forename: James M
authors.initials: JM
authors.lastname: Beerens
authors.affiliation: United States Geological Survey, Western Ecological Research Center, Dixon Field Station, Dixon, California, United States of America.
authors.forename: Joshua T
authors.initials: JT
authors.lastname: Ackerman
mesh_terms: D000818:Animals; D001717:Birds / Q000502:physiology*; D004784:Environmental Monitoring; D005241:Feathers / Q000187:drug effects; D005431:Florida; D018840:HSP70 Heat-Shock Proteins / Q000096:biosynthesis; D006801:Humans; D062070:Hydrology; D008628:Mercury / Q000633:toxicity*; D014874:Water Pollutants, Chemical / Q000633:toxicity*; D053833:Wetlands
chemical_list: D018840:HSP70 Heat-Shock Proteins; D014874:Water Pollutants, Chemical; D008628:Mercury