Scientific Name: Mustela nigripes
Status: Federally Endangered, State Endangered
These are large weasels, about the size of a mink, 18 – 22 inches long with a 4- to 6- inch tail. In color, they are yellowish brown above, with a blackish wash on the back, black feet and face mask, and a black-tipped tail. They are difficult to distinguish from domestic ferrets, but they are larger and heavier than the long-tailed weasel (which in Colorado seldom has a face mask).
Black-footed ferrets seem never to have been abundant in Colorado. They ranged statewide. Their habitat included the eastern plains, the mountain parks and the western valleys – grasslands or shrublands that supported some species of prairie dog, the ferret’s primary prey.
Little is known about the natural history of this rare mammal. Females do not exhibit the delayed implantation of embryos typical of the weasel family. Instead they mate in early spring and give birth to a litter of three or four mouse-sized pups after a seven-week gestation period.
Black-footed ferrets are reportedly killed by owls and coyotes. They are susceptible to distemper, and vehicles have killed them. However, it is reasonable to assume that plowing the prairie for agriculture and programs to eradicate prairie dogs drove the black-footed ferret to the verge of extinction.
Black-footed ferrets are considered an endangered species by both federal and state authorities.
Widely considered the most endangered mammal in North America, the black-footed ferret is making a comeback in Colorado and other parts of the West after being rescued from the brink of extinction in the mid-1980s.
Colorado Parks and Wildlife (CPW) has joined forces with the Utah Division of Wildlife Resources, the Bureau of Land Management (BLM), and the U.S. Fish and Wildlife Service (USFWS) to restore black-footed ferrets to their native range, which includes remote scrubland in Rio Blanco and Moffat counties in northwest Colorado.
Since 2001, state and federal wildlife biologists have established two major black-footed ferret colonies: one at Coyote Basin, which straddles the Colorado-Utah border west of Rangely, and another at the BLM's Wolf Creek Management Area southeast of Dinosaur National Monument.
So far, 126 black-footed ferrets have been released into the Colorado wilderness, with most of them raised in captivity at special breeding facilities. In 2003, however, the first interstate transfer of wild-born black-footed ferrets occurred and biologists successfully released them at Wolf Creek. The wild-born ferrets came from South Dakota's Conata Basin, the largest self-sustaining black-footed ferret colony in the United States.
In late-summer 2004, state and federal wildlife biologists for the first time confirmed that the ferrets appear to be persisting in their new Wolf Creek habitat, a chalky scrubland ecosystem of deep arroyos and steep ridges that is pocked with white-tailed prairie dog holes. During a 10-day spotlighting operation, researchers spotted at least five healthy black-footed ferrets and even captured and examined one of them. Sightings of black-footed ferrets had already been confirmed on the Colorado side of Coyote Basin. Before the restoration of black-footed ferrets in Colorado in 2001, the last record of a black-footed ferret in Colorado was in the 1940s.
The Wolf Creek region boasts a large, isolated white-tailed prairie dog town on land closed to off-road vehicle travel. During hot summer days, black-billed magpies hop across sun-baked highways to pick at road kill. At night, darkness muffles all sights and sounds, revealing only an inky, star-strewn sky. Black-footed ferrets prey on prairie dogs, their main source of food, and dwell in their burrows, making Wolf Creek and Coyote Basin ideal reintroduction sites.
However, because of the region's remoteness, locating black-footed ferrets can be difficult. Researchers say it can be like looking for a spider in a vast rain forest. Black-footed ferrets are by nature solitary, elusive hunters. The only way biologists can confirm their presence is by stalking them at night with large spotlights. When they shine the lights into the dark, they pick up "eye shine" from the mammals' large, bright eyes.
Wildlife researchers say black-footed ferrets have an unmistakable, brilliant emerald green eye shine. Each fall and winter, researchers conduct nocturnal spotlighting and daytime snow-tracking operations to confirm the well-being of the mammals. To undertake nighttime operations, biologists and volunteers don heavy backpacks that hold large batteries to charge their spotlights. Then they walk across miles of scrubland, through dusk and pitch-black darkness, as they track the elusive species.
The restoration of any threatened or endangered wildlife species is most successful when animals begin reproducing on their own in the wild. State and federal wildlife biologists plan to release more black-footed ferrets into the Colorado wild over the next few years, and expect to gather sufficient evidence to indicate whether the ferrets are reproducing. Black-footed ferrets mate in early spring and give birth to a litter of three or four mouse-sized kits after a seven-week gestation period.
With their elongated bodies, wide-spaced eyes, and long claws perfect for excavating dirt, black-footed ferrets closely resemble weasels. Unlike their weasel relatives, however, their fur does not change color in winter. Black-footed ferrets measure between 18-22 inches and are yellowish-brown in color, with a blackish wash on their feet and a characteristic dark mask around their eyes. Black-footed ferrets belong to the mustelid family, which means they produce a strong, musky body odor. They chatter and hiss when they feel threatened by predators, including owls and coyotes.
Since 1967, black-footed ferrets have been listed as endangered under the federal Endangered Species Act. Colorado researchers say there are records indicating unconfirmed sightings of the species in Moffat and Rio Blanco counties between 1976 and 1991. However, many of the sightings were by individuals who were unfamiliar with prairie dogs and black-footed ferrets.
The last official record of a black-footed ferret in Colorado was near Buena Vista in 1943. Experts say the widespread practice of poisoning prairie dogs during colonial-era expansion across the West has been a major factor in the mammal's demise. Continued population growth and urbanization in the region continue to affect the natural habitats of black-footed ferrets and other Great Plains and Rocky Mountain species.