Rethinking the evaluation of animal translocations

Translocations are the human-mediated movements of living organisms for conservation and non-conservation purposes. Conservation translocations have become popular and important conservation tools. Nevertheless, they commonly lack a standard definition of success and clear evaluation criteria. We used literature review to investigate if and how translocation success is defined and assessed, and how research and case studies have clarified drivers of success and failure. We reviewed primary scientific literature and the reports of the IUCN Global Reintroduction Perspectives (GRPs) that focused on translocations of raptors, species of high socio-ecological value but often endangered by human activities. We found that neither literature usually reported explicit definitions or standardised assessments of success. The only few definitions were mainly shaped by ecological and biological considerations, with success criteria varying based on translocation types. The GRPs included frequent mismatches across the report sections used to evaluate success. Despite ecological, species-intrinsic factors being commonly set as success indicators, the major difficulties encountered were usually methodological and socio-political, often concerning the conservation community. We call for a rethinking of success evaluation in translocations to better reflect their multidimensionality in research and practice, and further investigation of the challenges between conservationists. To guide future translocations, we propose an evaluation framework that acknowledges the multiple dimensions and subjectivity of success in its socio-ecological and methodological criteria for outcomes, process and learning perspectives at different timescales. We also recommend that the known importance of sociopolitical factors should favour a redefinition of the field from reintroduction biology to translocation science.