The last male purebred Columbia Basin pygmy rabbit has died, leaving just two females in a captive breeding program created to try to save the endangered species from extinction.

This undated image provided by the Oregon Zoo in Portland shows a Columbia Basin pygmy rabbit in their captive breeding program. According to a report Wednesday May 17, 2006, the last male purebred Columbia Basin pygmy rabbit has died, leaving just two females in a captive breeding program created to try to save the endangered species from extinction.[AP Photo]

The tiny rabbits are only found in Douglas County in north-central Washington. None are believed to exist in the wild, which means the two females - Lolo and Bryn are the only known purebred pygmy rabbits left in existence.

"This is a population that has existed since before the last Ice Age in Eastern Washington. The loss is something we can never calculate," said Jon Marvel, executive director of the Idaho-based Western Watersheds Project, which works to protect pygmy rabbit populations across the West. "Any time we lose a species it diminishes us all."

Biologists captured 16 rabbits in a remote area of Douglas County in 2001 to start the captive breeding program. The last of those rabbits, Ely, died March 30 at the Oregon Zoo in Portland, said Dave Hays, an endangered species biologist who oversees the program for the state Department of Fish and Wildlife.

The last two Columbia Basin rabbits, both offspring of the original captured rabbits, are at the Portland zoo.

The fate of the isolated species now rests entirely in a crossbreeding program with the closely related Idaho pygmy rabbit. The U.S. Fish and Wildlife Service has already determined that the crossbred rabbits will count toward recovery of the Columbia Basin species.

"The whole reason for the inner-crossing was to make sure we kept that genetic line going," said Chris Warren, a biologist overseeing the pygmy rabbit recovery effort for the federal agency. "Right now, we want at least 75 percent Columbia Basin ancestry in those animals."

The breeding program, conducted at the Oregon Zoo, Washington State University and Northwest Trek east of Olympia, now has 88 Idaho and mixed Idaho-Washington rabbits. There are 13 females in the breeding program with genes at least 75 percent Columbia Basin pygmy rabbit, Hays said.

Efforts to impregnate the two purebred Washington rabbits have been unsuccessful so far, he said.

Next month, biologists should know how many females are pregnant and how many crossbred babies will be born this year. Some of the rabbits will be released into Douglas County, perhaps as early as October, Hays said.

Biologists plan to build artificial burrows in shrub-steppe habitat within the next month in preparation for the release, said Beau Patterson, a state biologist in Wenatchee.