Meeting Abstract
Reproduction is an energetically demanding life history stage in which individuals must carefully manage energetic resources. Species reliant on capital stores for reproduction are under a unique set of constraints because they must accumulate substantial fat stores prior to reproducing; however, the underlying mechanisms influencing the accumulation of resources are currently poorly understood. Corticosterone (CORT) is an energetic hormone that influences resource acquisition and management, making it a strong candidate mechanism linking foraging behaviour, resource acquisition, and reproductive decisions. We implanted wild-living females with either a control or a dose of CORT to elevate plasma levels within a baseline range and deployed GPS units in Arctic-nesting common eiders, a mixed capital-income breeding strategy species. We quantified foraging behaviour and followed our hens through to reproduction to determine the effects of baseline CORT elevations on reproductive phenology. Our results suggest that elevated baseline CORT prior to investment in reproduction has a direct positive impact on resource acquisition and play a strong mechanistic role in driving variation in key life history decisions via influences on foraging. Additionally, testing these mechanistic relationships will provide researchers with the predictive capacity to understand how physiology may affect adaptability of Arctic-breeding species, particularly those facing increasing climatic variability.
