Circulating carotenoid concentrations are positively correlated with later clutch initiation in Florida Scrub-Jays (Aphelocoma coerulescens)

Circulating carotenoid levels are negatively associated with previous reproductive success in Florida Scrub-Jays (Aphelocoma coerulescens)

The relationship between individual fitness and antioxidants and oxidative stress has come under increasing scrutiny of late. In particular, associations between oxidative balance indicators and reproductive success in the wild have been inconsistent in the limited prior work on this topic. Studies spanning multiple seasons and antioxidant types are particularly lacking. Here, we examined associations between reproductive success over two breeding seasons and several metrics of circulating antioxidants (antioxidant capacity, uric acid, carotenoids, and vitamin E, measured in the intervening nonbreeding season) in Florida Scrub-Jays (Aphelocoma coerulescens (Bosc, 1795)). We found that carotenoid levels in the nonbreeding season were negatively associated with reproductive success in the preceding breeding season but unassociated with that in the subsequent breeding season. This correlation may be driven by the cost of reproduction (i.e., carotenoid depletion while breeding) or some other unmeasured and intercorrelated variable such as diet. Antioxidant capacity, uric acid, and vitamin E were not associated with reproductive success. These data are consistent with an emerging theme in physiological ecology: that antioxidants and oxidative stress are but one part of a suite of integrative physiological systems that interact and trade-off in complex ways, making full understanding of their ecological roles challenging.