Window on Nature
By Lowell & Kaye Christie, F47246
The word ferret is often used as a verb, but in this column we’re interested in the furry little critters you seldom see in the wild. The black-footed ferret was once common in the prairies and grasslands of North America, from central Canada to Texas and farther south. Now an endangered species, they’re rarely seen outside of zoos. And the black-footed ferret is definitely not the same species as those that people keep as pets, which have European bloodlines.
Nocturnal by nature, wild black-footed ferrets spend their days sleeping in prairie dog burrows (typically, that’s after they’ve eaten the original builder/resident). They are carnivores, after all, with a diet that historically centered on prairie dogs, along with the occasional rodent or small animal. Thus, when the vast prairies were plowed and planted, and masses of prairie dogs were trapped and poisoned, ferret populations also tumbled.
The black-footed ferret measures 18 to 24 inches long, and comes equipped with a 5- to 6-inch tail. Adult ferrets weigh in at 1½ to 2½ pounds, with males slightly larger than females. Ferrets are well-designed and adapted to their prairie environment. Their color and markings blend so well with grassland soils and plants that it’s tough to see one until it moves.
Ferrets are slender, wiry animals with a black face mask, black legs, and a black-tipped tail. The rest of their fur is a yellow-buff color, lighter on the belly and nearly white on the forehead, muzzle, and throat. The animal has short legs but large front paws and strong claws necessary for heavy-duty digging. A ferret’s large ears and eyes suggest it has acute hearing and sight, but its sense of smell is probably more important. As a nocturnal animal, it makes its living hunting prairie dogs underground at night.
You won’t see ferrets gathering for a family reunion. Loners for most of the year, males and females get together only for breeding in early spring. Then the male takes off for other pursuits, leaving the female to produce and care for the young. Approximately six weeks later she’ll bear three or four mouse-sized kits. Ferret kits are born blind and helpless, weighing a scant 5 to 9 grams.
You could hardly call such newborns cute, with only sparse white hair covering their bodies. After approximately three weeks, dark markings on the face, legs, and tail begin to appear, so when the kits’ eyes open at five weeks, and they see one another for the first time, they’re cute.
Black-footed ferret kits are three-quarters grown before they venture out of the burrow and see the sky, at which time the mother is still the provider. Long after they stop nursing, the kits rely on her to bring enough meat to sate their growing appetites.
By late summer, the mother begins parking her kits in separate burrows during the day, and getting them together after dark to teach them to hunt. Why? Maybe adolescent ferrets just can’t get along. By September school is over and the kits are on their own.
Now for the bad news. The black-footed ferret is the most endangered mammal in North America. Consider the statistics along this timeline.
In 1851 a book by John James Audubon and Rev. John Bachmann was the first to report and describe this mammal. No additional sightings were reported for the next 26 years. Thereafter, only occasional sightings arose.
In 1964 a small ferret colony was discovered in western South Dakota, causing some wildlife experts to assume these might be the last live black-footed ferrets in existence. They were wrong, but not by much. In 1969 the black-footed ferret was added to the endangered species list.
Years passed with fewer and fewer sightings of wild ferrets, so in 1979, when the last known captive ferret died, the black-footed ferret was declared extinct. But somebody forgot to tell a group of wild ferrets hanging out in Wyoming where, in 1981, a ranch dog killed a black-footed ferret. At least one had been alive.
Conservationists and researchers began an intensive search for wild ferrets. During the next three years they counted 129 black-footed ferrets, enough to start a captive breeding program in several different states. But when outbreaks of sylvatic (flea-borne) plague and canine distemper nearly wiped out the live ferrets, they recognized that there wasn’t much time.
Step one was to remove all known black-footed ferrets from the wild in an effort to save the species. Eighteen ferrets were captured between 1985 and 1987. It wasn’t much, but biologists worked with the animals they had, placing small family groupings into several different tried-and-true captive breeding locations.
Spirits soared when news came of two litters of ferret kits born at Sybille Wildlife Research and Conservation Education Center in Wyoming, bringing the ferret population all the way up to 25. In 1988, eight captive ferrets were taken from that group and sent to the National Zoological Park’s Conservation and Research Center in Front Royal, Virginia. The purpose of this was to start a new breeding colony, and to protect against another catastrophic loss of ferrets.
The ferret population stood at 120 after the 1989 breeding season. Several other facilities had become part of the captive breeding program, so optimistic ferret “experts” began planning for a release program.
Two years later, Shirley Basin in central Wyoming became the first black-footed ferret reintroduction site with the release of 49 juvenile ferrets. The Species Survival Plan developed to “manage the genetic and demographic needs of the captive ferret population” began building upon their success. By 1992, two litters of wild-born kits were reported at the Shirley Basin site, the first since the gathering of ferrets in the wild. Four wild-born litters were discovered at the site in 1993. Then the plague returned.
Such good news/bad news cycles made it clear that more breeding and more release sites were essential. But on the whole, ferret wins outnumbered the losses. Wild ferrets are now living (and prospering) in Wyoming, South Dakota, and Arizona, with more to come. We hope. At least a lot of good people are doing their utmost to ensure that the black-footed ferret will survive for a long time to come.