57.4 Thursday, Jan. 5 Do state-mediated hormones predict reproductive decisions in Arctic-nesting common eiders? HENNIN, H.L.*; BÊTY, J.; GILCHRIST, H.G.; LOVE, O.P.; University of Windsor, ON; Université du Québec à Rimouski; National Wildlife Research Centre, Environment Canada, Ottawa, ON; University of Windsor, ON email@example.com
Individual state and the abiotic environment are predicted to influence the reproductive decisions and therefore reproductive success of migratory species. Previous studies have shown that body mass and arrival date on the breeding grounds explain some of the variation seen in the reproductive success of Arctic-nesting, migratory species; however a substantial amount of variation is still unexplained. Using a state-dependent approach, our goal is to use physiological traits to enhance our ability to explain the variation seen in reproductive decisions and hence, reproductive success of individuals. We are studying a colony of Arctic-nesting common eiders (Somateria molissima) at East Bay Island, Nunavut, Canada. From 2006-2009, we collected blood samples from approximately 1000 pre-breeding females and assayed them for plasma baseline hormones (corticosterone and leptin), energetic metabolites (triglycerides), and oxidative stress levels, and recorded both the reproductive decisions (e.g. whether to reproduce, when to reproduce) and reproductive success (e.g. ability to hatch ducklings) of these individuals. We aim to determine the influence of these physiological traits in explaining the variation in reproductive decisions and reproductive success via correlative analyses and experimental manipulations in the field to test the causal relationships between individual state (physiology) and reproductive success. These results will provide insight into the evolution of mechanisms linking individual state and fitness in long-lived, migratory organisms.