62.5 Friday, Jan. 6 Plasma corticosterone and feather quality in the threatened Florida Scrub-Jay ELDERBROCK, E.K.*; SMALL, T.W.; SCHOECH, S.J.; University of Memphis; University of Memphis; University of Memphis firstname.lastname@example.org
Possessing feathers of high quality is important for survival and breeding success. However, because feather growth is energetically expensive, quality may vary with an individual’s condition. Most birds undergo a period of molt during which energy expenditure is directed primarily to feather growth. Concurrently, the stress response is suppressed resulting in lower levels of corticosterone (CORT), a hormone known to negatively affect feather quality. Thus, we expected that during the breeding season with energetic expenditures directed toward reproduction, feathers grown would be of lesser quality. Our study species, the Florida Scrub-Jay (Aphelocoma coerulescens) is a cooperative breeder in which offspring remain in their home territory from 1-3 years. Because non-breeder helpers are reproductively inactive, we anticipated that they would have more energy to allocate to feather growth and would, thereby, regrow feathers of higher quality than breeding birds. To investigate this we captured jays in the pre-breeding season (Feb-March), followed a standard capture and restraint protocol for a stress series to measure CORT, and removed two tail feathers. At the end of May, following fledging of young, we re-captured all birds and collected the two re-grown feathers. We assessed feather quality by measuring growth and fault bars, total length, and brightness based on spectrometric reflectance. Contrary to the above prediction, feathers of non-breeders had significantly more fault bars than those of breeders. Further, there was an overall trend of baseline CORT being positively correlated with the number of fault bars. These data suggest that endogenous CORT levels may impact feather quality but it remains unclear to what extent competing energetic demands influence feather growth in this species.