Bunny project breeds success
Cameras were clicking in central Washington March 13, when state Fish and Wildlife officials released 20 endangered Columbia Basin pygmy rabbits. Onlookers, enamored with the creatures’ fuzzy ears and dark eyes, were “just like paparazzi,” says Madonna Luers, department spokeswoman, “bunny paparazzi.”
The reintroduction was the culmination of a captive breeding program designed to save the rare rabbit, which is small enough to fit on a human hand (see a photo in an earlier HCN story). It’s the only rabbit in North America to dig its own burrows.
The state granted the Columbia Basin pygmy rabbit protection as an endangered species in 1993, after a decline attributed to loss of shrub-steppe habitat, fire, inbreeding and disease. In 2002, state biologists collected 16 of the remaining rabbits to begin a breeding program. The next year, the U.S. Fish and Wildlife Service declared the Columbia Basin pygmy rabbit an endangered distinct population segment. It’s the only federally protected pygmy rabbit; a petition to list the entire species failed because the agency said it provided insufficient information.
Rabbits being rabbits, officials initially thought that it wouldn’t take long for the captives to produce hundreds of offspring, says Luers. But reproduction wasn’t as successful as anticipated. In fact, numbers declined. The rabbits lacked genetic diversity, says Ken Warheit, geneticist for the state’s Department of Fish and Wildlife. Scientists concluded that inbreeding was leading to shorter breeding seasons, longer mating rituals, and increased susceptibility to disease; in essence, ineffective bunny sex.
So the scientists introduced three Idaho pygmy rabbits into the Columbia Basin captive breeding project in hopes of diversifying the genetic makeup. The rabbits released on March 13 are 75 percent Columbia Basin and 25 percent Idaho pygmy rabbits. To retain federal protection, all animals released in the wild must be at least 75 percent Columbia Basin pedigree.
The state Department of Fish and Wildlife and Washington State University are using radio transmitters to monitor the 20 rabbits. So far, raptors have picked off five rabbits. But three males have set out to find mates, traveling up to five miles off the Sagebrush Flat Wildlife Area release site, and two of the females appear to be preparing for kits by digging natal burrows.
Seventy pygmy rabbits remain in the captive breeding program, and the next batch could be released as early as this fall. Luers emphasizes, though, that the program has a lot of work ahead: “Putting a couple dozen rabbits out,” she says, “that’s a drop in the bucket.”