Meeting Abstract

68.5  Saturday, Jan. 5  Seasonal modulation of testosterone and stress response in a highly stable environment GONZALEZ-GOMEZ, PL*; MERRILL, L; VENEGAS, C; PANTOJA, J; VASQUEZ, RA; WINGFIELD, JC; Univ. of California Davis; Oklahoma State University; Universidad de Chile; Universidad de Chile; Universidad de Chile; Univ. of California Davis

Birds inhabiting seasonal environments typically have well defined breeding seasons, adjusting the production of sex hormones such as testosterone accordingly. Glucocorticoid hormones, meanwhile, mediate physiological and behavioral responses to changing environmental conditions, allowing animals to respond by improving the chances to survive. We examined the relationship of these hormones to breeding and molting condition in a wild bird in a highly stable environment with no environmental cues limiting the breeding or molting seasons. We collected baseline testosterone (T) and baseline and stress-induced corticosterone (CORT) in blood samples from Zonotrichia capensis during one year in the Atacama Desert, Chile. We expected low levels of T and CORT year-round. We did not find seasonality in breeding stages, and consequently T levels were affected by breeding condition, but not season. Molt did not follow any pattern or seasonality and it was negatively correlated with stress-induced levels of CORT. Molt and breeding stages overlapped at population and individual levels. Our results suggest that in absence of environmental challenges and cues, the adrenocortical stress response is regulated by physiological constraints such as feather production. Further research is needed to assess the role of social cues on T in breeding stage.