Meeting Abstract
Researchers have long been interested in relationships between the corticosterone (CORT) stress response and fitness. The CORT-fitness hypothesis predicts that increased environmental challenge leads to elevated baseline CORT and therefore decreased fitness. In contrast, the CORT-trade-off hypothesis predicts that CORT mediates the trade-off between survival and reproduction, and is therefore positively associated with survival and negatively associated with reproductive success. Finally, the CORT-adaptation hypothesis predicts that CORT increases reproductive success through higher energy expenditure towards reproductive behaviors such as foraging or incubation. All three of these hypotheses rely on varying levels of association between resource availability, CORT levels, individual behavior, and fitness. Previous studies have examined individual links, such as between resource availability and CORT, or CORT and behavior, but we lack complete datasets that examine all possible components to support or refute each hypothesis. Here, we present three years of data on a wild population of mountain bluebirds. We will explore associations between territory quality, body condition, CORT levels, and reproductive success to determine the relationship between CORT and fitness. We hope that by measuring all components necessary to evaluate the predictions of the various CORT-fitness hypotheses, we can shed light on complex associations between CORT and fitness.
