Studyingbird flyways by ringing and δ2H: a contribution for the conservation of European birds

During post-breeding migration, for many European intra-Palearctic and trans-Saharan migratory species, Alps may represent an important flight-corridor, followed at different altitude, crossing mountain passes or flying over uplands and valleys. Moreover, the alpine chain has been demonstrated to be set along a migratory divide that separates eastern and western populations of the central and northern population of the Western Palearctic during post-breeding migration. In order to better understand geographic origin and direction of migrators, and to underline the importance of Alps for the conservation of European birds during migration, we analyzed a recovery data set including observations until 2008, referred to 15 species, of which individuals were ringed or recaptured within the alpine region; the aim was to identify their hypothetical breeding origin and wintering destination belts. Then, we analyzed deuterium (d2H) stable isotope ratios in feathers of individuals of the same species, sampled during post-breeding migration in the years 2010-2013 on an alpine pass in central Italian Alps. We used the presumed areal of provenance obtained by recoveries of each species and calibrated deuterium isotopic maps (isoscapes) as suggested by several authors. The aim was to model probability surfaces to determine geographic origin of the sampled individuals.