Meeting Abstract
Reproduction is energetically demanding. For birds investing in energy rich eggs, adequate resource acquisition during the spring pre-breeding period is vital for the formation of eggs and the development of energy stores to last through incubation. In species with female-based mono-parental care, male reproductive investment can occur in the form of mate or territorial defense. The energetic costs associated with mate guarding in the pre-breeding period and the mechanisms linking male condition to female reproductive success are poorly understood. Common eiders nesting at East Bay Island, NU are a model species to explore the relationship between male and female state because both members of each pair are captured and sampled simultaneously during the pre-breeding period. We expected if males expend significant amounts of energy defending their mate from extra-pair copulations or defending her foraging territory then male eider condition would decline and its female mate’s condition would increase. Further, we examined whether variation in male energetic physiology (corticosterone, triglycerides, beta-hyroxybutyrate, and immunoglobulin Y) was able to predict the subsequent condition of their paired female, and by extension her subsequent breeding decisions. We hypothesized that males in lower relative condition, with higher CORT and BOH, and lower TRIG and IgY, ultimately benefited via their females laying earlier. These results help explain indirect drivers of reproductive timing and success in common eiders, and identify mechanisms underlying sex-specific reproductive trade-offs.
