Columbia Basin Pygmy Rabbit (Brachylagus idahoensis) Reintroduction and Genetic Management Plan: Addendum to Washington State Recovery Plan for the Pygmy Rabbit (1995)

This plan addresses the recovery strategy for the federal and state endangered Columbia Basin pygmy rabbit (Brachylagus idahoensis) in shrub-steppe habitat of central Washington. It is a consolidated update of the 2010 genetic management plan and the 2007 reintroduction plan for the pygmy rabbit. Technical background for the plan, covering the history, biology, and ecology of pygmy rabbits, has been reviewed extensively in a 5-Year Status Review (USFWS 2010) and an amendment to the federal Draft Recovery Plan (USFWS 2011) for the Columbia Basin distinct population segment of the pygmy rabbit.

Currently, there are no wild pygmy rabbit populations known to occur in Washington's Columbia Basin. As a result, the recovery strategy relies on the reintroduction of captive-bred pygmy rabbits originating from the joint captive population maintained since 2001 at Northwest Trek, Oregon Zoo, and Washington State University, in conjunction with the release of wild pygmy rabbits captured from other populations within the species' historic distribution. The reintroduction plan was formulated with information gleaned from studies of pygmy rabbits in the wild, results of the 2002-04 pilot-scale reintroductions in southeastern Idaho, results of a trial 2007 release of animals into Washington, and comparable reintroduction efforts for other endangered species.

Beginning in the spring of 2011, pygmy rabbits were reintroduced at Washington Department of Fish and Wildlife's Sagebrush Flat Wildlife Area. Released rabbits included captive Columbia Basin lineage rabbits and wild rabbits from other range states to obtain the numbers and genetic diversity needed for the likely establishment of the population. A combination of small soft release enclosures and large enclosures were used for the releases with different enclosures and holding times tailored to the needs of wild, captive-bred, adult, young, male or female pygmy rabbits. Reintroduced adult individuals were fitted with radio collars and will be tracked to document habitat use, dispersal, mortality factors, reproductive success, seasonal and annual survival rates, and changes in population genetics. After the release of most captive-bred pygmy rabbits in 2011 and 2012, the breeding program will be de-emphasized.

Wild animals from other range states will be used for subsequent translocations in the years after the majority of the captive population has been reintroduced. Numbers, timing, and sites selected will be dependent upon the success of the initial releases, as well as the availability of rabbits from other states. If the reintroduced population at Sagebrush Flat achieves a desirable growth trajectory and population size, and assuming rabbits remain available from other states for continued release efforts, reintroductions will proceed sequentially to previously identified and prioritized recovery areas. Baseline stochastic population models suggest that a single reintroduced subpopulation of pygmy rabbits could grow rapidly so that multiple sub-populations could be created in a managed metapopulation in approximately 10 years.