Three litters of endangered Columbia Basin pygmy rabbits have been born in the past week at the Oregon Zoo in Portland and at Washington State University (WSU) in Pullman– the result of an on-going joint effort to recover the animals from near-extinction.
The litters were born May 1 to 5 to rabbits that were brought from the wild last year in an attempt to save the genetically unique population. Additional litters are expected in June.
The adult rabbits were collected from eastern Washington in a joint project coordinated by the Washington Department of Fish and Wildlife (WDFW) in cooperation with the U.S. Fish and Wildlife Service. The project seeks to boost the vanishing pygmy rabbit population by breeding and rearing the animals in captivity and then releasing them back into the wild.
Fewer than 30 Columbia Basin pygmy rabbits are believed to remain in their native eastern Washington shrub-steppe habitat. Although the causes are not fully known, scientists believe the rabbits' precipitous decline is chiefly due to loss of native sagebrush habitat. The Columbia Basin population was listed for protection under the federal Endangered Species Act last November.
As they do in the wild, the rabbits at the Oregon Zoo and WSU gave birth outside the entrances to the burrows they have created in their captive quarters. Following the births, the mothers carry their off-spring down into their nests. After the babies are stowed in the burrow, the mothers close off the entrances, re-plugging the openings each time they leave the nest.
The number of new rabbits will be determined once the juveniles re-emerge from the nest, typically about two weeks after they are born.
The new-born rabbits, which nurse in the evening, initially measure only two-and-a-half inches long.
"These captive births are a crucial step in recovery of this unique population," said David Hays, WDFW endangered species specialist. "Our goal is to increase the wild population while maintaining the rabbits' genetic fitness. We hope to test the first release of Washington pygmy rabbits next year."
In addition to the rabbits at the Oregon Zoo and Washington State University, Northwest Trek Wildlife Park in Pierce County is breeding pygmy rabbits from Idaho. The more plentiful Idaho rabbits will be used to test release techniques in Idaho that will be used later in this state with the endangered Washington rabbits.
For more information and photographs of the joint pygmy rabbit recovery effort visit the WDFW Science Magazine on the Internet.