Translocations spur population growth but fail to prevent genetic erosion in imperiled Florida Scrub-Jays

Land and natural resource use in addition to climate change can restrict populations to degraded and fragmented habitats, catalyzing extinction through the reinforced interplay of small population size and genetic decay. Translocating individuals is a powerful strategy for overcoming direct threats from human development and reconnecting isolated populations but is not without risks.¹ Habitat Management Plan analyses under section 7 of the U.S. Endangered Species Act determined that multiple subpopulations of Federally Threatened Florida Scrub-Jays (Aphelocoma coerulescens, hereafter FSJ) belonging to a metapopulation on Florida's west coast were declining demographic sinks, occupying areas where agriculture and fire suppression had degraded and fragmented the habitat.² In order to increase the viability of the overall metapopulation, 51 FSJs from five of these small subpopulations in areas to be mined were translocated throughout 2003-2010 into a larger site of more contiguous, recently restored habitat at the core of the metapopulation, which contained a small resident population.³ Prior to translocations and for nearly two decades afterward, this core population, referred to as the M4 core region (CR) population, was extensively monitored, yielding a nearly complete pedigree. We used this pedigree, along with temporal genomic analyses and simulations, to show that translocations coupled with habitat restoration generated rapid population growth, but high reproductive skew increased inbreeding and led to genetic erosion. This mechanistic understanding of mixed conservation outcomes highlights the importance of monitoring and the potential need for genetic rescue to offset consequences of reproductive skew following translocations, regardless of demographic recovery.