Meeting Abstract
65.1 Tuesday, Jan. 6 Physiological and demographic effects of roads on an endangered, old-growth specialist and a common generalist BUTLER, L.K.*; RIES, L.; HAYDEN, T.J.; BISSON, I.-A.; WIKELSKI, M.; ROMERO, L.M.; Tufts Univ.; Univ. of Maryland; Engineering Research and Development Center; Princeton Univ.; Max Planck Inst. for Ornithology; Tufts Univ. luke.butler@tufts.edu
The Golden-cheeked Warbler (Dendroica chrysoparia) is an endangered migratory bird that prefers to nest in large tracts of mature forest and suffers increased nest predation as forest edge increases. We tested the hypothesis that forest edge in the form of roads, a threat to habitats and interior-dependent animals around the world, would cause stress in breeding adult warblers. We tested the prediction that baseline and stress-induced corticosterone (CORT) concentrations would differ in males near edge than in males far from edge. Based on the common understanding of glucocorticoid function we might predict higher corticosterone in more stressed males, but growing evidence suggests that chronic stress can result in lower CORT concentrations. In agreement with this new view of chronic stress, baseline CORT appeared to decrease as road density increased in the breeding habitat of Golden-cheeked Warblers. We also tested the predictions that males breeding in areas with more edge would have lower body condition than interior males, and that older, more experienced males would be more common in interior patches and less common near roads. For comparison, we tested the same predictions in the White-eyed Vireo (Vireo griseus), a common and widespread migrant that does not appear to avoid edges and breeds in a variety of habitats including Golden-cheeked Warbler habitat. We also injected White-eyed Vireos with adrenocorticotropic hormone (ACTH) to test the prediction that road density affects adrenal sensitivity to stimulation by the pituitary. Our results illustrate whether an endangered bird is more susceptible to stress due to habitat alteration than a common bird breeding in the same place.
