Interactions of Corticosterone with Feeding, Activity and Metabolism in Passerine Birds

Abstract

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Coping with a challenging environment: Effects of seasonal variability and reproductive status on glucocorticoid concentrations of female baboons (Papio cynocephalus)

“…Associated with the changes in feeding time, increased ambient temperatures, and increased exposure to sun, we found that female baboons had elevated fGC concentrations from July to October. These data are consistent with those reported in the literature for various animal species subjected to food deprivation (Astheimer et al, 1992;Harper and Austad, 2000;Kitaysky et al, 2001a;Tsuma et al, 1996). Moreover, water sources become progressively more scarce, smaller in size, and poorer in quality in Amboseli as the dry season progresses.…”

“…Although short-term, acute stressors result in several-fold increases in GC levels in some studies (Astheimer et al, 1992;Boonstra et al, 2001;Jessop et al, 2000), the elevations in fGC concentrations found in our study were much less (<20%), and were similar to that reported by Sapolsky (1986) in his comparison of male Anubis baboons in drought vs. non-drought years. The environmental stressors here and in Sapolsky's comparison are long term and chronic, rather than acute, and may therefore have major impacts through smaller, persistent and cumulative effects.…”

“…These effects are in part mediated via increases in glucocorticoid (GC) concentrations (Astheimer et al, 1992;Kitaysky et al, 2001bKitaysky et al, , 2003reviewed by Boonstra, 2004;Landys et al, 2006;Romero, 2002 andKitaysky, 2002). The classic illustration of the ecologically adaptive nature of the GC response (e.g.…”

“…The majority of research has been on single acute stressors, either approached through experimental laboratory studies or, in a few cases, through nonexperimental evaluation of acute natural stressors in the field. In experimental laboratory studies, researchers have usually created such stressors by exposing animals to various single environmental stressors for short period: extreme heat (Larsson et al, 1983;Lowe et al, 2002;Olsson et al, 1995Olsson et al, , 1996; review by Silanikove, 2000); cold temperatures (DeVries et al, 1997;Filipovic, 2007); food or water deprivation (Astheimer et al, 1992;Dunlap, 1995;Li et al, 2000;Lynn et al, 2003;Tsuma et al, 1996; see also review by Harvey et al, 1984). A few experiments have used a combination of two acute stressors simultaneously, e.g.…”

“…Another approach has evaluated acute environmental challenges in natural contexts by examining changes of GC concentrations in free-ranging animals following intense, relatively brief stressors such as severe storms (Astheimer et al, 1992(Astheimer et al, , 1995Wingfield and Kitaysky, 2002;Wingfield and Ramenofsky, 1997). As expected for an acute stressor, in all of these studies researchers observed a rapid and short activation of the hypothalamic-pituitary-axis (HPA), resulting in elevation of GC levels and inhibition of functions not needed for survival in the immediate future.…”