Re-introduction of the Columbia Basin pygmy rabbit in central Washington, USA

Summary

The Columbia Basin population of the pygmy rabbit (Brachylagus idahoensis), a genetically distinct, federally endangered population confined to Washington's sagebrush steppe, went extinct in the wild after its last 16 individuals were captured for captive breeding in 2001, following decades of habitat loss to agriculture. A decade of ex-situ captive breeding across three facilities produced too few healthy rabbits, hampered by inbreeding depression, disease and poor juvenile survival, even after Idaho rabbits were added for genetic rescue; in 2011, the Washington Department of Fish and Wildlife shifted strategy entirely, phasing out captive breeding for large predator-resistant outdoor enclosures in native sagebrush habitat, where captive-origin rabbits interbred freely with 110 wild rabbits translocated from Oregon, Nevada, Utah and Wyoming between 2011 and 2013. Releases scaled up rapidly from 64 captive-reared adults and juveniles in 2011 to 830 rabbits, including 113 adults, released from four enclosures in 2014, focusing on juveniles since enclosure-born kits, less habituated to humans and more exposed to natural risk, fared better in the wild than captivity-raised adults; over 90% of eligible surrounding land was enrolled in Safe Harbor Agreements protecting cooperating landowners. Post-release monitoring combined short-lived VHF glue-on transmitters with non-invasive winter burrow surveys and fecal DNA genotyping, detecting 39%, 13% and 11% of released rabbits surviving to the following winter across 2012-2014 and confirming some wild reproduction, though overall recruitment has remained low. The project rates itself only partially successful given how young the program remains, crediting the pivotal shift from captive to naturalized enclosure breeding, strong landowner participation, and volunteers providing about 75% of fieldwork.