Contrasting mechanisms driving the northward expansion of African raptors in Europe

Abstract The contrasting mechanisms driving the northward expansion of African raptors into Europe provide a unique opportunity to understand how these species overcome substantial geographical barriers and a major biogeographic boundary. To explore these mechanisms, we analysed three species currently expanding across the Afro‐Palaearctic system: the Atlas Long‐legged Buzzard ( Buteo rufinus cirtensis ), Rüppell's Vulture ( Gyps rueppelli ), and White‐backed Vulture ( Gyps africanus ). Using species distribution models based on topo‐climatic predictors, we estimated environmental favourability for breeding across 6203 operational geographic units and compared outputs with breeding records, recent sightings, ecological traits, and evidence of interspecific interactions. Our results reveal contrasting colonization pathways. The Atlas Long‐legged Buzzard shows broad climatic favourability across North Africa and parts of southern Europe, indicating a climate‐driven range expansion facilitated by increasingly favourable environmental conditions. By contrast, African vultures exhibit negligible climatic favourability in Europe, despite multiple field observations, including hybrid breeding attempts with Griffon Vultures ( Gyps fulvus ) in the case of Rüppell's Vultures, while observations of immature White‐backed Vultures remain few and anecdotal per se, yet they have been recorded increasingly and more regularly over the past few years. This mismatch suggests that vulture colonization in Europe is unlikely to be climate‐mediated and may instead be facilitated by socially assisted vagrancy, with immature African vultures following migratory Griffon Vultures and integrating into their social and spatial networks. Our findings thus show that African raptors may be transgressing current biogeographic boundaries through fundamentally different mechanisms, with climate‐driven expansion in buzzards and socially mediated dispersal in vultures, underscoring the importance of integrating behavioural ecology and interspecific interactions into predictions of species redistribution under global change.