Feather deuterium as an indicator of age‐class in the Pectoral Sandpiper Calidris melanotos

Abstract

We measured deuterium isotope ratios (δDf) in primary feathers to distinguish first‐year from older Pectoral Sandpipers Calidris melanotos captured in Barrow, Alaska, during the breeding season. δDf showed a distinct bimodal distribution, and model‐based clustering placed the δDf values into two non‐overlapping groups. More negative δDf corresponded to Arctic areas, probably identifying first‐year birds with Arctic‐grown juvenile feathers retained from the previous year. The more positive values corresponded to lower latitudes, possibly identifying older birds that grew their feathers at non‐Arctic latitudes.