Zoo helps restore nearly extinct ferrets in US West

WASHINGTON — Animal keepers at the National Zoo's conservation center in Virginia sent 26 black-footed ferrets to "boot camp" Wednesday to prepare the critters for life in the wild as part of an ongoing effort that has fueled the recovery of a species once declared extinct.

Black-footed ferrets, the only ferret species native to North America, disappeared in the late 1970s. Then in 1981, a ranch dog in Wyoming killed a small animal, and the dog's owners showed the creature to a taxidermist. That led biologists to discover a colony of wild black-footed ferrets. By 1985, though, there were just 24 left.

Over time, scientists decided to collect those last ferrets to try to save them. Only 18 survived. Many scientists were skeptical and worried it was too late to save the species, said David Wildt, now the head of the Center for Species Survival at the Smithsonian Conservation Biology Institute, a branch of the National Zoo.

"Can you go down to as few as 18 animals and be able to bring those animals back?" Wildt recalled wondering at the time. "There aren't a lot of examples of successful reintroduction programs."

The ferret's struggle may surprise those who keep ferrets from Europe as pets. American ferrets used to be common across the Great Plains. Tens of thousands once lived across 12 states.

Prairie dogs are their main food source, but disease and extermination of prairie dogs, considered a nuisance on land for cows, starved the ferrets.

Thirty years later, the ferret population is on the rise.

Zoos in Louisville, Ky., Toronto, Phoenix, Colorado Springs, Colo., and the Smithsonian's National Zoo joined with the U.S. Fish and Wildlife Service to breed the endangered animals.

The Smithsonian developed the first artificial insemination technique for ferrets, which has produced 139 kits, and scientists are building a ferret sperm bank to maintain the population's genetic diversity. So far, five kits have been produced using frozen sperm.

"That has never been done before with respect to endangered species," Wildt said. "Here you have a model, not just in terms of producing animals for reintroduction, but the science."