By Eileen Dowd Stukel

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Nothing ever seems to be easy for the black-footed ferret. First listed as a federal endangered species three decades ago, this mustelid is often called one of the rarest mammals in the world.

Those who have followed the plight of this elusive creature can recite the pertinent events. Biologists studied a small population in southcentral South Dakota during the late 1960’s, capturing some of the animals for a first, unsuccessful try at captive breeding. Some of the captive ferrets died after being inoculated to protect them against canine distemper. All that remain of South Dakota’s ferrets are haunting photos of what were feared to be the last members of the species. In 1981, discovery of a black-footed ferret population near Meeteetse, Wyoming renewed hope that the species hadn’t gone the way of the passenger pigeon and Audubon’s bighorn sheep.

The conservation community breathed a collective sigh of relief, and biologists again studied the members of this population to try to understand reasons for its rarity. Then a double disease disaster hit. Sylvatic plague infected the white-tailed prairie dogs that provided both food and shelter for the Meeteetse ferrets. Canine distemper struck the ferrets themselves, threatening the future of the only known black-footed ferret population. Eighteen animals were eventually captured, forming the nucleus for a captive breeding program under the direction of the Wyoming Game and Fish Department. This time, captive breeding was successful, producing enough progeny to begin the long journey back for a species once found in 12 states and two Canadian provinces. Several facilities in the U.S. and Canada now participate in captive breeding.

As state and federal agencies considered where best to release ferrets, South Dakota soon became a leading contender for the few precious candidates available for the risky operation known as reintroduction. South Dakota’s prairie dog species is the black-tailed variety, which generally forms denser colonies than the white-tailed prairie dog. South Dakota has no history of plague and has many thousands of acres of tribal and public lands.

Social factors are also considered during reintroduction planning. Most of us have no direct experience with endangered species reintroductions. Uncertainties abounded in South Dakota about impacts to private landowners and users of public lands.

Partly to assuage such fears, the first South Dakota ferret introduction occurred within the boundaries of Badlands National Park. The reintroduced ferret population, like all before and since, is legally classified as an experimental, nonessential population, which affords slightly greater management flexibility.

After years of planning, both legal and biological, black-footed ferrets finally touched South Dakota soil again in 1994. The experimental population designation isn’t just bureaucratic jargon. Each reintroduction is designed as a scientific experiment, so other sites and perhaps similar species can benefit from the results. South Dakota’s 1994 contingent included ferrets with prairie dog experience (preconditioned) and others with no exposure to prairie dogs or their burrows (naïve). Naïve ferrets were "soft-released", meaning they were held in enclosures for approximately 10 days and provided with food and protection from predators. Preconditioned ferrets were released relatively soon after arriving at the reintroduction site, a practice known as a "hard-release".

Not surprisingly, this solitary, nocturnal, mostly subterranean mammal is difficult to monitor. Reintroduction sites, to date found in the states of Wyoming, South Dakota, Montana, and Arizona, have employed a variety of monitoring techniques. They include following radio-collared animals from the ground and air; reading implanted transponder chips; snow-tracking; spotlighting in summer; and general searching for tracks, scat, burrows plugged by prairie dogs, and trenching by ferrets.

Follow-up monitoring during the summer of 1995 yielded encouraging results from the 1994 reintroduction of 36 predominately juvenile animals at the Conata Basin / Badlands site. Spotlight-toting observers discovered at least two wildborn litters. Results from both South Dakota and Montana indicated the superiority of preconditioned ferrets. Nearly three dozen preconditioned ferrets were hard-released at the South Dakota site during the fall of 1995, with a supplemental release of seven animals a few months later. Spotlighting during the summer of 1996 again heartened those pulling for this masked creature. Surveyors found at least five and possibly as many as seven litters, evidence that this species could potentially make the transition from captivity to life within an unforgiving landscape.

But all wasn’t rosy with black-footed ferret reintroduction. Predators posed a serious threat. South Dakota’s 1996 release featured two new components. Ferrets were released both on Badlands National Park and Buffalo Gap National Grassland, bringing full meaning to the Conata Basin / Badlands site name. Electric fencing designed to exclude predators was erected on prairie dog towns. Ferrets were placed within the predator exclosure with the hope that they would gain a survival advantage if initial predator pressure was reduced. Because of past encouraging results and the site’s continued good fortune in avoiding serious disease threats, South Dakota received the lion’s share of ferrets in 1996. Nearly seventy ferrets, again nearly all juveniles, were released in the South Dakota site in 1996. Predators struck again, with coyotes and great horned owls as the prime suspects.

Although initial monitoring results were promising, recent spotlight surveys have revealed fewer ferrets than expected at the 1996 release sites. Spotlighters found no ferrets at 1994 and 1995 release sites in Badlands National Park. Have ferrets dispersed to prairie dog towns of their own choosing? Are these third or fourth generation ferrets "wilder" and more difficult to detect in thicker cover? Has the dreaded disease threat caught up to the South Dakota site?

By the time this article appears, the 1997 South Dakota release will be well underway. To help meet the demand for preconditioned animals, the Forest Service erected preconditioning pens in the Conata Basin this last summer, occupied by more than 40 juvenile ferrets. This group will comprise more than half of South Dakota’s 1997 allocation. The mysterious fate of ferrets previously found on the 1994 and 1995 release sites will hopefully be discovered. In addition to annual changes in experimental design, the ferret reintroduction trial at the Conata Basin / Badlands site will be evaluated after five years of releases are completed.

The national recovery goal for the black-footed ferret is to achieve a population of 1500 animals divided among at least 10 sites. If this goal is achieved, species status will be downgraded from endangered to threatened. Further strides will result in its removal from the federal list of threatened and endangered species.