Predictors of past avian translocation outcomes inform feasibility of future efforts under climate change

Conservation translocations – the intentional movement of individuals from one area to another for conservation purposes – provide a potential response to climate change, but can be costly and risky. To help improve translocation outcomes and assess their feasibility as a climate adaptation tool, we analyzed past conservation translocations (176 bird species at 680 sites globally) as a proxy for future efforts. To determine predictors of annual survival of released birds, we used generalized linear mixed models. Species with larger bodies and relative brain size had higher survival. Survival was also higher in protected areas, with subsequent releases at a site, for more recent years, and where the initial cause of decline was removed (n = 435 releases). Of particular relevance to climate-motivated translocations, longer distance translocations decreased survival; there was no evidence that greater climate differences between source and release sites (n = 117 releases), or releases beyond the indigenous range (“managed relocation”, n = 435 releases), reduced survival. We also assessed how reproduction varied with release rates (birds/year) and species' generation lengths. Species with long generation lengths released at high rates had similar reproductive success to species with short generation lengths released at low rates. These findings can improve conservation translocation decisions by informing expected outcomes for target species, and identifying site features and management practices that maximize the likelihood of success. We also provide an empirical assessment of potential challenges of using conservation translocations in response to climate change, including evidence that longer distance translocations may be less feasible than shorter distance translocations.