Meeting Abstract
Early life conditions may have large impacts on the ways animals respond to stressors as adults; however, it is difficult to monitor most free-living animals over the course of their lives to assess the effects of these early conditions. Here, we test the prediction that environmental conditions experienced during critical developmental stages impact the hormonal mediators of the response to stressors in adults. To do so, we use a long-term dataset of Tree Swallows (Tachycineta bicolor) with records from both natal development and adult breeding. Specifically, we focus on how adults respond to stressors during incubation and provisioning of nestlings via corticosterone (CORT) responses because, in this population, adult CORT levels during these stages predict reproductive success. We saw no effect of developmental conditions on baseline CORT during incubation, or on baseline CORT or stress-induced CORT response during provisioning. However, we saw a negative relationship between average temperature during the incubation stage of development and stress-induced CORT response during adult incubation, suggesting that conditions during development can influence the way Tree Swallows respond to challenges as adults. We found no relationship between chick CORT phenotype and probability of fledging or recruitment, demonstrating that the relationships seen in adults are unlikely to result from differential survival of chicks with different CORT phenotypes. Fully understanding the mechanisms that link natal conditions to adult CORT phenotypes requires studies of juveniles post-fledging, a poorly understood life stage. Overall, our results suggest that early life conditions can have long-term impacts on individuals and their reproductive success.
