Meeting Abstract
Studies using wild animals in laboratory-based research require bringing wild-captured organisms into a novel setting, which can have long-lasting impacts on physiology and behavior. In several species, captivity stimulates stress hormone production and can alter immune function. Despite this, little is known about how captivity influences stress hormone regulation, or if captivity-induced changes in stress hormone production and regulation mediate changes in immune function. In this study, we investigate the influence of captivity on the physiology of a wild bird commonly-used in laboratory-based research, the house sparrow (Passer domesticus). We tested how captivity influences stress endocrinology, immune responses, and organ mass, and also investigated if the production or regulation of corticosterone, the main stress hormone in birds, mediated changes in immunity or organ size. We found that baseline and ACTH-induced corticosterone levels increase following captivity and remain elevated after 9 weeks of captivity. Wound healing also was influenced by time spent in captivity, with birds taking 2 days longer to heal if they were wounded after 3-6 weeks in captivity when compared with birds that were wounded immediately upon capture. Additionally, captivity caused notable reductions in spleen, liver, and brain mass within 24 days of captivity, and this reduction persisted for at least 9 weeks. Together, these results imply that captivity can have long-lasting effects on house sparrow corticosterone release and immune function, and suggest that, even after 9 weeks, house sparrows do not acclimate physiologically to life in captivity.
