Disrupted natal habitat imprinting triggers long-distance dispersal in captive-bred eagles

Abstract Dispersal behavior and survival are critical properties of animal populations and are known to determine the success of reintroduction and reinforcement programs. We tracked 53 juvenile Aquila fasciata (Bonelli’s Eagle), including wild-hatched and captive-bred individuals released via two different protocols, to test how early-life experiences shape dispersal and fitness outcomes. Captive-bred eagles were released either on their rearing site near their natal enclosure and foster parents or at a distant site without the parents. Dispersal patterns diverged strongly by group: distant-released individuals dispersed farther, and in markedly more directional, migration-like patterns, reaching as far as East Africa and the Arabian Peninsula. In contrast, on-site and wild-hatched eagles remained closer to their natal areas, showing variable and shorter dispersal trajectories on average. Despite comparable ages at dispersal onset, habitat use differed significantly, with distant-released individuals consistently occupying drier desert habitats. These patterns suggest that post-fledging experience promotes philopatry and shapes movement decisions, likely via natal habitat preference induction. Wild-hatched eagles exhibited significantly higher survival rates and recruitment success than both captive-bred groups, which suffered elevated mortality primarily due to electrocution and other anthropogenic threats. Surprisingly, shorter-range dispersal by on-site releases did not improve survival, likely reflecting high risk from local infrastructure (notably high incidents of electrocution). The high mortality of captive-bred birds raises concerns about the long-term effectiveness of current release strategies and highlights the paramount importance of conserving existing wild breeding pairs and their territories. Our findings demonstrate that both dispersal and fitness outcomes are influenced by the timing and spatial context of the release to the wild, with strong implications for raptor conservation and reintroduction programs. In particular, we highlight the importance of acquiring natal habitat preference during the post-fledging dependence period and recommend that release protocols preserve continuity with natal habitat when possible. Ultimately, this study underscores that fine-scale management of early-life experience can have enduring consequences for the spatial ecology and viability of reintroduced populations.