Evaluating the efficacy of translocation: maintaining habitat key to long-term success for an imperiled population of an at-risk species

The conservation of species at-risk has involved a wide range of recovery methods including population augmentation. Yet, there has been little formal evaluation of the efficacy of this potentially high risk and expensive approach. In the late 1990s, 32 mountain caribou (Rangifer tarandus caribou) were translocated to the Telkwa caribou herd in an effort to recover this declining population. We used Andersen-Gill survival models to explore the influence of forestry, linear features, and recreation on the survival of translocated and native caribou in the Telkwa herd as well as two control herds that had relatively little habitat disturbance and no translocation. We used location data from radio/GPS collars to monitor the mortality of individual caribou from the three populations over a 21-year period (1991-2012). Results suggested that forest harvest more negatively affected the survival of Telkwa caribou when compared to neighbouring herds and that translocated caribou were not predisposed to higher mortality relative to native caribou. Although the translocation effort stabilised the decline of the Telkwa caribou for a 10-year period, this herd has now declined to 22 individuals. Our research suggests that well managed translocation programs can result in the short-term stabilization or increase of small and declining populations of species at-risk. To achieve long-term recovery objectives, however, conservation strategies must address the underlying causes of decline. For woodland caribou in the mountains of western Canada, this requires managing anthropogenic disturbance to minimize densities of primary prey and their predators that act in concert to decrease the survival of adult caribou.