The only surviving pair of endangered pygmy rabbits released as part of a program to increase their numbers in the wild have dodged coyotes, badgers, hawks and owls and found time for love.

Proud scientists announced Thursday that the rabbits have successfully bred.

"We were worried. It took them a little while, but they did what rabbits do best," Rod Sayler, a Washington State University conservation biologist, said from Pullman.

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The rabbits, slightly larger than a man's hand, eat sagebrush and are the only rabbits in the United States that dig their own burrows.

No Columbia Basin pygmy rabbits are known to be left in the wild. Predators nearly wiped out the population of 20 captive-reared Columbia Basin pygmy rabbits released in March in central Washington.

Two males that wandered outside the study area were captured and taken back to the captive breeding program, leaving only an adult male and female in the wild as of June 1.

But spirits were buoyed last week when doctoral student Len Zeoli found the female digging a burrow and lining it with grass, an indication she was preparing to give birth.

Later, Zeoli spotted a juvenile rabbit near another burrow from what is believed to be a second litter of babies, called kits , Sayler said.

The male, which WSU students nicknamed Utapau after a planet in the "Star Wars" movies, and Impala , the female, could breed again this year, Sayler said, noting that rabbit pairs can mate two to three times a season.

Each litter produces from four to six kits.

It is not known whether the two litters came from the same female, or if one was the offspring of another female that was later killed by predators, he said.

But it's encouraging that there is more than one litter, Sayler said.

"We considered that our first goal; to have that breeding success," he said. "Our next goal is to have animals survive longer and have more kits."

The Sagebrush Flat Wildlife Area where the captive rabbits were released is considered the last native home of the Columbia Basin pygmy rabbit. The rabbit was listed as a state endangered species in 1993 and protected under the federal Endangered Species Act in 2003.

The reasons the Columbia Basin rabbits declined are not precisely known, although scientists suspect inbreeding among such a small population was a major factor. Range fires, farming, disease and predators also are thought to have taken their toll.

No more rabbits are known to exist in the wild.

Descendants of the last 16 wild rabbits captured at the site have been crossbred with pygmy rabbits from Idaho, and some of those animals were released at Sagebrush Flat.

Because the offspring have at least half of the Columbia Basin pygmy rabbit's genes, they are considered the real thing.

WSU's Department of Natural Sciences, the Oregon Zoo and Northwest Trek near Tacoma, working with the Washington Department of Fish and Wildlife and the U.S. Fish and Wildlife Service, are raising between 75-100 pygmy rabbits for eventual release.

Another release could come as early as this fall, Sayler said. Additional steps will be taken to protect the females, such as erecting fences or cages around burrows to keep predators out, Sayler said.

"We're going to do everything we can to really increase the survival of the females," Sayler said. "It will take years, maybe three to four years, of releases to get a population large enough to be sustaining. This is the first really tiny step."