High long-term survival and asymmetric movements in a reintroduced metapopulation of Cinereous vultures

Post-release mortality and movements are critical factors of translocation failure. Yet, survival and movement reflect different demographic and behavioral processes and may therefore have contrasted responses to management, although they are often very difficult to disentangle in animal populations. To provide guidance in animal translocations, we discriminated the respective roles of survival and movement in the long-term dynamic of a translocated metapopulation of Cinereous vultures (Aegypius monachus) in France using multievent capture-recapture analyses of reintroduced (n = 119) and wild-born individual (n = 163) observations. Annual apparent survival rates were high and structured in age (>0.8 for young and >0.9 for adults) and did not differ between individual origin (wild-born or released), release methods (aviary or hacking) nor between regions (Alps and Causses), except for those released in the Alps experiencing a reduced survival for one year after release. In contrast, age structure movements differed between populations and origin status. Wild-born young from the Causses were more erratic than those from the Alps and older individuals, whereas vultures reintroduced in the Causses demonstrated restricted movements during their first year after release. Despite such asymmetric movements, we overall highlight a strong tropism of individuals whatever the region and their origin. Since movement and survival were respectively higher and lower in young compared with adults, we recommend to first release adults in the primary stage of metapopulation translocations for increasing the establishment success at the release site. Further releasing young and securing successful breeding into the wild would increase demographic growth and between-population connections.

Automated summary

This study investigated the effects of age and origin on survival and movement of translocated vultures. The results showed that age and origin were important factors influencing the survival and movement of vultures. The study recommended releasing adult vultures first to increase the success of establishment at the release site.