A Rare Species Gets a Second Chance
Twenty-five years after the black-footed ferret was rediscovered in the wild, a successful captive-breeding program is giving the endangered animal a new lease on life
IF NOT FOR the unlikely duo of Shep and Scarface, the black-footed ferret might be just a distant memory, gone forever from the prairie lands of North America. Indeed, three decades ago scientists could not find any of the creatures surviving in the Great Plains region, where as many as half a million once played a key role in the ecosystem by keeping prairie dog populations in check. Some experts believed the continent's only native ferret was extinct. Then Shep, a ranch dog in Meeteetse, Wyoming, changed their minds.
On a brisk September morning in 1981, Shep brought home tangible evidence that the endangered species still existed in the wild when he caught a black-footed ferret near the ranch. Biologists rushed to the area and eventually discovered more than 120 of the bandit-masked creatures.
For a time, these ferrets seemed to hold their own. But in 1985, after dozens of the animals succumbed to disease, researchers began capturing the remaining animals and putting them in a safe holding facility. By 1987, only 18 survivors--possibly the rarest mammals on Earth at the time--became the focus of a last-ditch captive-breeding program.
At first, however, things did not go well. No young were born the first year. But subsequently a male ferret dubbed Scarface saved the day--and possibly his species--by siring litter after litter of robust kits, buying time for the scientists to learn the intricacies of raising a mysterious, little-studied animal.
Today, 25 years after the species' rediscovery, about 500 black-footed ferrets are now living in the wild in six U.S. states and one state in Mexico. Another 350 or so survive in captivity. "Ferret recovery has been a huge success story," says Mike Lockhart, the U.S. Fish and Wildlife Service (FWS) biologist who coordinates the recovery program at the National Black-footed Ferret Conservation Center near Fort Collins, Colorado. "Ferrets do well when released in good habitat and we can see the potential for someday downlisting the species." The overall downlisting goal: to have 1,500 ferrets in 10 locations, with at least 30 breeding adults in each population.
Before that goal is achieved, however, several obstacles remain, including program funding. "We don't even have enough people to run the FWS breeding facility properly, which is needed to keep recovery going," says Tom Dougherty, a senior advisor for the National Wildlife Federation and member of the black-footed ferret recovery implementation team.
Another major problem is a shortage of suitable habitat for reintroduction. Members of the weasel family, black-footed ferrets feed almost exclusively on prairie dogs. They also eat, sleep and raise their young in prairie dog burrows. "They are one of the most specialized carnivores in the world," says Dougherty. "To thrive, they need large prairie dog towns. You can't have ferrets without prairie dogs."
Prairie dogs once numbered in the billions throughout the western plains, but after suffering through decades of government eradication programs and habitat loss, the rodents today occupy just a small fraction of their former range. Eight years ago, NWF petitioned unsuccessfully to have the black-tailed prairie dog, the most widespread species, listed as "threatened" by FWS. "The prairie dog is a keystone species," say Dougherty, "Not only ferrets but dozens of other animals and plants depend on its habitat for survival."
Today, without protections, black-tailed prairie dogs are not even safe on federal land. Last year, for example, bowing to a rancher's complaints and political pressure, the U.S. Forest Service poisoned the animals on 3,000 acres in the Conata Basin in South Dakota's Buffalo Gap National Grassland. The Conata Basin supports 250 wild ferrets--the most successful recovery site to date--and it provides habitat that is free from sylvatic plague, an introduced disease spread by fleas.
Prairie dogs and ferrets have no immunity to the disease; it can sweep through a dog town like wildfire. On Montana's Fort Belknap Indian Reservation, another release site for ferrets, plague struck quickly in 1999, decimating the area's prairie dogs. Without their prey, the number of ferrets plummeted on the reservation to only five documented animals. Despite such difficulties, Lockhart is optimistic. "There's a vaccine for plague that is showing promise," he says, pointing out that if an oral method of delivery could be developed for prairie dogs, core habitats supporting ferrets might be preserved. "This is a watershed year," he adds. At this writing, authorities had plans to release ferrets in three new sites.
At the breeding center in Colorado, Lockhart leads a visitor past dozens of large outdoor pens where captive-bred ferrets go through 60 to 90 days of "survival school," learning how to capture prey. One ferret sticks its head out of its burrow, then quickly disappears when it spots humans. "A tremendous amount of energy and money has gone into this recovery effort by federal and state governments, Native American tribes and private organizations," says Lockhart. "Twenty-five years ago, we were given a second chance and we have made tremendous headway toward recovery. It would be such a waste if we fail now."
South Carolina journalist Doreen Cubie visited the ferret breeding center in Colorado for this article. Her feature on another endangered species, the snail kite, also appears in this issue.
The Trick to Finding Ferrets
Black-footed ferrets are nocturnal and secretive. Once released into the wild, they can disappear down a prairie dog hole, never to be seen again during daylight. To keep tabs on them, scientists use spotlights to look for the creatures' distinctive emerald green eyeshine at night. All captive-born ferrets released into the wild also have two transponder chips implanted under their skin. Researchers place circular transponder readers around an entrance to a burrow, and when an occupant goes in or out, they can determine whether the animal was born in the wild or in captivity.