Meeting Abstract

44.2  Saturday, Jan. 5  Does corticosterone deposited in feathers in autumn predict circulating corticosterone during breeding? HANAUER, RE*; KETTERSON, ED; Indiana University; Indiana University

The adrenal steroid hormone corticosterone (CORT) is involved in the regulation of energy balance, behavior, and stress responses. Individuals differ in the degree to which they elevate CORT in response to acute stress, and in some species this has been shown to be a stable trait over the individual’s lifetime. In birds, CORT is generally measured by taking blood samples immediately after capture and again 30 minutes later. Interest has grown in measuring CORT extracted from feathers because it is not affected by the process of capture, and it provides a longer-term measurement integrated over the time it took the feather to grow. Feather CORT has been found to correlate with an individual’s elevated circulating CORT in response to an acute stressor. However, previous work reported circulating CORT during feather growth. It is unknown if this relationship holds in birds whose feathers grew months earlier. I compared hormone levels from feathers and blood samples to determine whether feather CORT might be a reliable predictor of circulating CORT during the breeding season. Wild male dark-eyed juncos (n=80) were captured during the breeding season at two sites in southern California. Blood samples were collected at 0 and 30 minutes after capture. One tail feather, which had grown the previous autumn during molt, was collected, along with measures of endo- and ecto-parasites. Results will reveal whether circulating CORT correlates with feather CORT deposited several months earlier in a wild passerine and which measure of CORT is a better predictor of the prevalence of parasites. This study will be useful to researchers interested in less-invasive methods, and will inform future research in the fields of animal personalities, eco-endo-immunology, and conservation.