Meeting Abstract

62.5  Sunday, Jan. 5 14:30  Carotenoid coloration and the breeding molt trade-off in Cardueline finches BRAZEAL, K.R.*; HAHN, T.P.; Univ. of California, Davis; Univ. of California, Davis krbrazeal@ucdavis.edu

Carotenoid coloration in birds has long been studied for its role in sexual selection because it signals male quality and correlates with mating success. However its relationship with molt timing is less well understood. This link is important because carotenoids are deposited into feathers during molt. Testosterone may be an important mediator of the relationship between carotenoids and molt since it has been shown to play a role in carotenoid signaling as well as in timing of the breeding-molt transition. We examined the relationship between carotenoid coloration and molt timing in T-treated and non-T-treated captive male house finches and pine siskins. More brightly colored individuals (i.e. redder house finches and larger yellow wing patches in pine siskins) tended to molt later in non-T-treated groups of both species. Further, in house finches, redder birds had greater molt delay and less breeding-molt overlap in response to T-treatment. Therefore, enhanced carotenoid coloration seems to have a negative association with molt. From a sexual selection perspective, this may be because birds with greater carotenoid coloration are more likely to attract mates late in the breeding season and would therefore benefit more from delaying molt and investing in current reproduction. The proximate relationship between carotenoids and molt timing is unclear. Carotenoids in the blood could directly influence molt, or alternatively, factors related to male quality (e.g. body condition) could affect both coloration and molt timing. Either way, testosterone is likely to be a mediating factor since individuals differ in their responses to T-treatment.