Meeting Abstract

38.7  Tuesday, Jan. 5  Environmental and life-history correlates of glucocorticoid physiology in an arid-country bird BUTLER, L.K.*; HAYDEN, T.J; ROMERO, L.M.; The College of New Jersey; Engineering Research and Development Center; Tufts University lbutler@tcnj.edu

We investigated hypothalamic-pituitary-adrenal axis activity in a free-living migratory songbird that exhibits an uncommon suite of environmental and life-history traits. Painted Buntings at our study site in Texas breed in areas altered heavily by human activity, and in areas relatively undisturbed by people. Male Painted Buntings show striking delayed plumage maturation, with males in their first breeding season appearing drab green and nearly identical to females, and older males exhibiting an unmistakable bright red and blue plumage. Accordingly, males usually do not breed in their first season on the breeding grounds. Finally, unlike most temperate migratory songbirds, Painted Buntings at our study site in Texas do not molt on the breeding grounds after breeding, but molt only after migrating to special molting grounds in the Mexican monsoon region. We compared baseline and stress-induced corticosterone concentrations between disturbed and relatively undisturbed habitats; between first year and older males; and between the start and end of the breeding season in Texas. We used these intra- and interspecific contrasts to address how glucocorticoids help animals cope with predictable and unpredictable challenges from the environment.