Stable isotopes (δ2H) in feathers identify non-breeding origins of the endangered Jankowski’s Bunting

There is sparse and contradictory information concerning the migratory status and non-breeding range of the endangered Jankowski’s Bunting Emberiza jankowskii, precluding the possible development of conservation measures dedicated to protecting habitats occupied across the full-annual cycle. To unravel the migratory strategy and identify the non-breeding grounds of Jankowski’s Bunting, we collected feathers on breeding birds in Inner Mongolia, analysed their deuterium concentrations (δ2Hf) and produced probabilistic geographic assignments to origin to assess where these feathers were likely grown. We compared results from this exercise to current knowledge of the breeding and non-breeding range to evaluate likely moult origins thereby informing migratory connectivity in this species. Winter moulted feathers were not grown in the same isotopic environment than summer-grown feathers, attesting some non-breeding dispersive movements, and geographic assignments favour the hypothesis of a short-distance dispersion during the non-breeding season.