The effects of West Nile virus on the reproductive success and overwinter survival of eastern bluebirds in Alabama.

We tested for negative effects of West Nile virus (WNV) on a breeding population of eastern bluebirds in Alabama by comparing fecundity and reproductive success in years before and after the arrival of WNV and by comparing fecundity, reproductive success, and overwinter survival of seropositive and seronegative individuals within the same population in the same years. We found that female bluebirds were more likely to be seropositive than male bluebirds. Age and individual condition did not affect likelihood of being seropositive. Being seropositive for WNV was not associated with any negative effects on reproduction or survival. However, female fecundity was higher in years after WNV compared to years before the arrival of WNV. The reproductive success of males who tested positive for WNV exposure was higher than that of males that were seronegative. Overall, we found no negative effects on reproduction or survival after exposure to WNV.