Translocations contribute to population rescue in an imperiled woodpecker

Abstract

Anthropogenic destruction and fragmentation of habitat restrict many species to small, isolated populations, which often experience high extirpation risk. Restoring connectivity through translocations is one approach for mitigating the demographic and genetic perils faced by small populations. However, translocation interventions often lack substantial postrelease monitoring, and thus important information including the performance of translocated individuals, the long-term impacts on the recipient population, and the extent to which management objectives are fulfilled over time are often poorly known. Here, we examined the establishment dynamics and long-term outcomes of translocations from multiple donor populations into an intensively monitored population of the federally threatened red-cockaded woodpecker. We found evidence that translocations contributed to population growth and led to genetic admixture within the population. The translocated birds provided direct demographic benefits through high rates of establishment, breeding, and survival. We found that the survival and lifetime reproductive success of individuals were positively related to their amount of translocation ancestry, indicating that demographic benefits extended beyond the direct performances of the translocated birds. The translocations diversified the population’s genetic composition with the ancestry of most individuals in the latter years of the study deriving from multiple translocation donor populations. We found marked heterogeneity in the genetic contributions of translocated individuals and cohorts, leading to disproportionate representation of certain lineages. Encouragingly, despite some accumulation of inbreeding during the study, the translocations thus far have not substantially contributed to inbreeding. Our findings illustrate in precise detail how translocations can be an effective approach for managing imperiled taxa.