The U.S. Fish and Wildlife Service has completed a five-year review of the endangered Columbia Basin pygmy rabbit and today announced some sobering results. The agency has been trying to bring Washington’s subpopulation of North America’s smallest rabbit back from the brink of extinction since 2001. But so far, the recovery effort hasn’t helped much.
Not only is the species still endangered, the latest review concluded, but there are also three new threats to the species. The rabbit was so far gone by the time it was listed under the Endangered Species Act that the government implemented a captive breeding program to make sure it would continue producing offspring. In 2008, the last purebred Columbia Basin pygmy died in captivity, so the feds started cross-breeding the species with other subpopulations, which the Service determined earlier this month are not in danger of extinction.
Unfortunately, the captive breeding program for the Columbia Basin pygmy created its own set of threats to the rabbit population, including:
1. Increased risk from disease in captivity
2. Decreased survival capabilities as a result of captive conditions
3. Loss of genetic uniqueness because of interbreeding
From Fish and Wildlife:
“The pygmy rabbit is the smallest rabbit in North America. Adults weigh
about one pound and measure less than a foot in length. In the wild, pygmy
rabbits are typically found in sagebrush habitat, and primarily eat
sagebrush, native bunchgrasses, and other perennial plants. The pygmy
rabbit is one of only two rabbit species in North America that digs its own
burrows and therefore is most often found in areas that include both
suitable foods and relatively deep, loose soils that allow burrowing.
Historically, the Columbia Basin pygmy rabbit was likely found in
appropriate shrub-steppe habitat in portions of Douglas, Grant, Lincoln,
Adams, Franklin, and Benton Counties, Washington.
The last known population of the Columbia Basin pygmy rabbit in the wild
was believed to be extinct by mid-2004, although other wild populations may
still occur in unsurveyed areas of central Washington. In 2007, twenty
captive-bred pygmy rabbits were reintroduced to central Washington habitats
historically occupied by the species. These captive-bred animals
experienced a high level of predation and it is unlikely any survived
through the fall of 2007. Biologists will be able to apply knowledge
gained from that release to help improve survival rates of future releases.
The Service considers the Columbia Basin pygmy rabbit a DPS because the
population is separate from others of its kind and its conservation is
significant to the remainder of the species. The Columbia Basin pygmy
rabbit has been isolated from other pygmy rabbit populations for at least
10,000 years, as suggested by the fossil record and genetic analyses. This
DPS is the only population of the species that occurs in the unusual
ecological setting of the Columbia Basin and it is markedly different
genetically from other pygmy rabbit populations.
“Recovery of the Columbia Basin pygmy rabbit will require creative
efforts,” said Ken Berg, Manager of the Service’s Washington Fish and
Wildlife Office in Lacey, Washington. “Close collaboration with our
partners and stakeholders will be essential to an effective recovery
program for this population.”
The Service, in partnership with the Washington Department of Fish and
Wildlife, has a program to enroll non-federal land owners who are
interested in helping conserve the Columbia Basin pygmy rabbit.
Participation in the voluntary Safe Harbor Agreement provides landowners
and managers with assurances that future land-use restrictions will not be
imposed on them if they voluntarily implement management measures that
would be expected to benefit the Columbia Basin pygmy rabbit.”