Long-distance post-release movements challenge the metapopulation restoration of Bearded Vultures

Abstract

Restoring ecological dynamics is a key objective of conservation translocations. Exemplarily, reconnecting the reintroduced alpine populations with native Pyrenean populations through re-establishing locally extinct populations in between, in the Causses and the Pre-Alps, is a major goal for the long-term conservation of Bearded Vultures in Europe. Understanding Bearded Vultures' post-release movements and foraging behavior is critical to understanding the settlement of newly restored populations and to supporting conservation measures. The telemetric monitoring of 43 translocated and wild-born juveniles allowed us to investigate whether differences exist in post-release movements and foraging behavior during the first year of life between reintroduced and native populations. Medium- and long-distance exploration movements start during the spring following fledging for both translocated and wild-born individuals. However, birds translocated in the most distant release site (Causses) exhibited greater exploration distances with no clear directional movement pattern, had smaller home ranges, and had a stronger preference for supplementary feeding stations than those from other populations. Although some birds translocated in the Pre-Alps displayed similar behaviors, the pattern is not as strong as in the Causses, likely because of the proximity to the breeding populations reintroduced in the Alps or differences in the number and management of supplementary feeding stations. Preference for supplementary feeding stations (SFS) mostly occurred in the Pre-Alps and the native populations, but was lower in the Causses. Seasonal variations in SFS preference were consistent among populations, with a peak in the first spring following fledging. Beyond documenting post-release movements in Bearded Vultures, we suggest better accounting for the demographic consequences of behaviors to track conservation translocation effectiveness, at both local and regional scales.