Abstracts

Presented by Jerad Henson - Email: jhenson2@cbu.edu

Many bird species exhibit a seasonally variable glucocorticoid response to a standardized capture and handling protocol. Corticosterone (CORT), the primary avian glucocorticoid, is elevated in response to a wide-range of stressors to facilitate the mobilization of energetic resources. It is believed that the seasonal variation in CORT responsiveness aids the individual in coping with changing energetic demands while protecting valuable protein and lipid resources. Although this variation has been observed in many bird species, very few studies have examined this phenomenon in waterfowl. We examined whether mallards alter CORT response during the fall and winter and whether this was related to body condition. We sampled mallards during three periods at two locations: 1) fall, during pre-migration in North Dakota (n = 25), 2) fall and early winter, during migration in Arkansas (n =5), and 3) late winter, during the early spring migration in Arkansas (n = 13). Mallard CORT response and body condition were compared across sample periods. CORT response was reduced during fall migration and increased during the late winter when mallards complete breeding pair formation. However, body condition and CORT response were not correlated. These results are similar to other studies that found a reduced CORT response during migration and molt, and increased responsiveness associated with breeding behaviors.