Meeting Abstract
Ornaments are thought to honestly signal individual quality to potential mates. Individual quality may include the ability to cope with stress through the production of glucocorticoids (GCs), which help to redirect resources from growth to survival. However, increases in GCs can also have negative physiological consequences, such as inducing oxidative stress due to the stimulatory effects GCs have on cellular respiration. Thus, an important question is whether high quality individuals, with more elaborate ornaments, can mitigate some of the negative effects of a strong stress response (i.e., a high increase in GCs) if they are more resistant to oxidative stress. We studied this question in the common yellowthroat (Geothlypis trichas). Male common yellowthroats have two sexually selected plumage ornaments, a melanin-based black mask and a carotenoid-based yellow bib. We measured the acute stress response as the increase in corticosterone (CORT), the main GC in birds, in response to the stress of handling. As predicted, we found that males with more elaborate ornaments (larger masks and bibs with more carotenoid chroma) had a greater increase in CORT during an acute stress response, and the increase was relatively greater if males also had stronger resistance to oxidative stress. These results suggest that individuals with the most attractive ornaments may be able to mitigate the physiological costs of an acute stress response by mounting a stronger response to oxidative stress.
