Black-footed ferrets are saved from extinction, but where will they live?
by Marty DurlinIn late October, biologists in Arizona’s Aubrey Valley spent five nights in a row trapping and tagging black-footed ferrets, considered “the most endangered mammals in the United States.” They found 29, which means that there are probably about 70 ferrets altogether in this reintroduction area south of the Grand Canyon.
According to Jeff Pebworth, wildlife program manager with the Arizona Game and Fish Department, the Aubrey Valley site is “coming on strong” because “now we’re at the stage where the ferrets are reproducing in the wild.”
An estimated 1,000 black-footed ferrets live in the wild, all descendants of 18 animals captured in Wyoming in the late 1980s. The 20-year, $30 million project to bring the animal back from extinction is a success, but ironically, the recovered species may now have no place to live, says Mike Lockhart, national black-footed ferret recovery coordinator with the U.S. Fish and Wildlife Service.
Described by John Audubon and James Bachman in 1851, black-footed ferrets may once have been plentiful on the Great Plains, but their numbers have always been hard to estimate because of their nocturnal habits. Distinct from their European-bred counterparts in pet stores, black-footed ferrets are indigenous to North America. In the same family as mink, weasels, skunks and badgers, the ferrets are 18 to 24 inches long, including a 5 or 6 inch tail, and weigh about two and a half pounds. They are a yellow-buff color, nearly white on the face with a black face mask and black feet.
The ferrets depend completely on prairie dogs for both food and shelter. One ferret can eat about 110 prairie dogs in a year. They hunt at night, moving in a series of galloping jumps from one prairie dog burrow to the next, killing their sleeping prey with a bite to the back of the neck or throat. The ferrets then adopt the burrows as their own, spending about 90 percent of their time underground.
First listed as endangered in 1967 by the U.S. Fish and Wildlife Service under a precursor to the Endangered Species Act of 1973, black-footed ferrets nearly died out because prairie dogs were dying. Poisoned by ranchers and the federal government, their habitat squeezed by human activity and their numbers decimated by plague, prairie dogs are now relegated to about 2 percent of their original habitat.
By 1972, biologists believed black-footed ferrets to be extinct. But in 1981, a dog killed a ferret on a ranch in Wyoming. This led to the discovery of a small population near Meeteetse.
In October 1985, the Wyoming Game and Fish Department, in cooperation with the Fish and Wildlife Service, captured six black-footed ferrets to start a captive breeding program near Wheatland, Wyo. During the fall of 1986 and spring of 1987, the last known wild black-footed ferrets were placed in breeding facilities there.
The recovery effort led by the U.S. Fish and Wildlife Service is a collaborative project among state agencies, nonprofit organizations and several Native American tribes, including the Lakotas at Cheyenne River, Rosebud and Lower Brule in South Dakota, and the Assiniboine and Gros Ventre at Fort Belknap, Mont.
Currently, 14 programs in 10 areas receive ferrets from the National Black-footed Ferret Conservation Center in northeastern Colorado, the primary breeding facility, and release them into their native habitats. There are reintroduction programs in Montana, South Dakota, Wyoming, Colorado, Utah, Arizona, New Mexico and Chihuahua, Mexico.
The goal of the breeding program is to establish 240 adults in captivity while continuing to return ferrets to the wild. To forestall a single catastrophic event that could eliminate the entire population, the captive ferrets were divided into groups. Five zoos also have breeding programs – Toronto, Ontario; the National Zoo in Virginia; Louisville, Ky.; Phoenix, Ariz.; and Colorado Springs, Colo.
At the northeastern Colorado breeding facility, ferrets live in indoor environments, where black plastic tubing masquerades as tunnels and raw hamburger as prairie dogs. Before the ferrets are released, they’re put outside in pens with real prairie dog burrows, acclimating for 30 days to the temperatures, sights, sounds and smells of the earth and sky.
The animals are tagged before they’re released and again after they’re trapped during an annual “spotlighting” event, when ferrets living in the wild are counted, as in Arizona’s recent five-night effort.
But even as ferrets recover, food and habitat for the animals are becoming scarce. Prairie dog populations are at about 5 percent of their historic levels and the ferret’s favored prairie habitat is also the target of energy companies.
The Bureau of Land Management was forced to suspend gas and oil drilling leases on more than 29,000 acres of public land in the Uinta Basin of Utah last year, after an internal review board found that leases were issued illegally and could put the black-footed ferret recovery at risk.
And so as one arm of the federal government saves the ferret, another arm threatens its livelihood. The BLM “needlessly risks even our most endangered wildlife,” said Erin Robertson, staff biologist for the Center for Native Ecosystems, a nonprofit based in Denver. “The oil and gas industry already controlled over 80 percent of the potential ferret habitat in the Uinta Basin. The internal review board did the right thing by saying that the BLM needs to consider all of our resources before granting more drilling rights.”
Fish and Wildlife’s Lockhart says there has been “incredible progress” with black-footed ferrets, which he attributes to collaboration and partnerships. That said, he is not hopeful about the species’ chances for flourishing in the wild. Finding and maintaining suitable habitat continues to be a challenge, he says, adding, “It would be a horrible thing if we can’t carry this species to recovery.” © High Country News