In 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.”
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