PULLMAN -- The six pygmy rabbits captured from the wild and brought to Washington State University (WSU) last month have multiplied to 11.
Dr. Lisa Shipley of the WSU Natural Resource Sciences College reports that one of the adult female rabbits gave birth to five "kits" or bunnies earlier this month. Shipley hopes more reproduction occurs in her experimental captive rearing project that was launched to help recover the state endangered species.
Washington Department of Fish and Wildlife (WDFW) biologists captured the pygmy rabbits in northcentral Washington's Sagebrush Flats Wildlife Area, which may be the species' last stand in the state.
Annual pygmy rabbit burrow surveys have shown a steady decline, but intensive monitoring this past spring by WDFW biologists and Shipley's graduate student Nikki Siegel showed numbers dangerously low. That's when WDFW and other scientists decided to initiate the captive rearing part of a state recovery plan, with the hope of releasing more rabbits into the wild in the future.
Habitat loss has been the greatest single factor in the species decline, and recovery strategies have focused on restoration. But now at reduced populations, predation of young may be critical. Captive rearing allows the young to grow in a safe environment and perhaps have a greater chance of survival upon release.
The WSU campus facility for rearing the rabbits is designed to protect them against hawks, coyotes, badgers, and other natural predators. It was patterned after a similar facility at the Oregon Zoo in Portland where Idaho pygmy rabbits are being successfully reared.
The pygmy rabbit (Brachylagus idahoensis) is the smallest rabbit in North America; an adult rabbit can fit in the palm of a hand. It is patchily distributed in sagebrush-dominated areas of Oregon, California, Nevada, Utah, Idaho, Montana, Wyoming, and Washington. It is uniquely dependent on sagebrush for food and shelter, digging burrows in the deep, loose soil in which dense stands of sagebrush thrive.
Washington populations are separate from the core of the species' range and were historically found in sagebrush habitat in Benton, Adams, Grant, Lincoln and Douglas counties. Currently, fewer than 100 pygmy rabbits are known to survive in isolated fragments of suitable habitat in Douglas County. Loss of sagebrush habitat to agricultural conversion has been the primary factor in the decline.
The pygmy rabbit was listed as a state threatened species in 1990, upgraded to state endangered status in 1993. It is listed as a candidate species by the U.S. Fish and Wildlife Service (USFWS), which was recently petitioned to list it as federally endangered.