Using stable-hydrogen isotopes to reveal immigration in an Arctic-breeding songbird population

Background: Knowledge of immigration and emigration rates is crucial for understanding of population dynamics, yet little is known about these vital rates, especially for arctic songbirds. We estimated immigration in an Arctic population of northern wheatears on Baffin Island, Canada, by the use of stable hydrogen isotopes in tail feathers (d2HK). We assumed that d2HK values of juvenile (hatch-year) feathers grown at the breeding grounds were representative of the local population, while those of breeding adults were indicative of where they grew their feathers during their postbreeding molt the previous year. The extent to which adul