Spatial patterns in hydrogen isotope ratios in feathers of Burrowing Owls from western North America

Abstract

ABSTRACT Deuterium (2H) has been used to track movements of land birds, under the assumption that δ2H in precipitation (δ2Hp) and δ2H in bird feathers (δ2Hf) are correlated across broad geographic gradients. The nature of this correlation has been evaluated only in a small percentage of the birds that breed in North America. We sampled Western Burrowing Owl (Athene cunicularia hypugaea) feathers of known origin (nestling feathers) at 36 locations throughout North America (from southern Canada to central Mexico). We used a modification of the “comparative equilibrium” technique of Wassenaar and Hobson (2003) to measure the δ2H of nonexchangeable hydrogen in feather samples. We characterized the strength of the relationship between δ2Hf and amount-weighted mean annual δ2Hp in a raptor that breeds in arid grasslands and deserts throughout western North America. We used a Bayesian hierarchical approach to model the δ2Hf–δ2Hp relationship, accounting for levels of intrinsic and extrinsic variation in δ2Hf. We ...