Further Evidence for Site Fidelity to Wing Molt Locations by King Eiders: Integrating Stable Isotope Analyses and Satellite Telemetry

Abstract

Abstract Studies using stable-isotope analyses of feathers to determine molt locations in marine birds are increasingly common but generally lack verification through ground-truthing. In this study, we examined the stable isotope compositions of wing feathers from King Eiders (Somateria spectabilis) implanted with satellite-transmitters. We compared stable carbon, nitrogen, and hydrogen isotope compositions (δ13C, δ15N, and δD, respectively) of primary feathers with the geographic location of wing molt in the subsequent year. Longitude of molt locations of eiders was highly correlated with δ13C (r2 = 0.69, N = 12) and δD (r2 = 0.90, N = 12) isotope values from their primary feathers grown in the previous year. There was no relationship between δ15N and location of wing molt (r2 = 0.007, N = 12). The results of this study provide further evidence for site fidelity during wing molt by King Eiders.