Résumé
This research employed stable isotope analysis to investigate the migratory patterns and geographic origins of Eleonora's falcon (Falco eleonorae) and its associated prey species within the Galite Archipelago of Tunisia. Feathers collected from both juvenile and adult falcons along with their prey were analyzed for deuterium isotopic composition using the IsoriX package in R, which facilitated geographic assignment based on stable isotope ratios. The results demonstrated no significant difference in deuterium values (δ 2 H) between adult and juvenile individuals of Eleonora's falcon, indicating a lack of geographic variation in molting locations among different age groups. However, the isotopic data for adult falcons yielded unexpected results, suggesting origins close to the sampling site, which contradicted the anticipated patterns of migration to distant wintering grounds. Furthermore, this study successfully mapped the origins of various prey species, indicating a broad geographic intake ranging from the Mediterranean to southern Scandinavia. These findings highlight the complexity of migratory behaviors in predatory birds and underscore the efficacy of stable isotope analysis as a tool for ecological research in avian migration studies.