A Challenging Future for the Black-footed Ferret

By Pete Gober

The black-footed ferret (Mustela nigripes) is a small, weasel-like animal with a long, slender body marked by black feet and a black mask. Once feared to be extinct, it is among our nation’s rarest animals. Black-footed ferrets depend almost exclusively on prairie dogs, which provide food and shelter.

Historically, black-footed ferrets occurred across a very large area of central North America, wherever prairie dogs existed, from southern Canada to northern Mexico. Over the past century, prairie dogs, along with ferrets, were vastly reduced in number by the conversion of native prairie habitats to cropland, the poisoning of prairie dogs to reduce forage competition with domestic livestock, and a non-native disease (sylvatic plague). Prairie dogs no longer occur in the large, unbroken colonies that once extended for miles, their range having been reduced by over 95 percent. Accordingly, recovery efforts for the ferret must adapt to difficult circumstances.

In 1979, the black-footed ferret was widely presumed to be extinct after the last few individuals from a population in South Dakota died in captivity without successfully breeding. Fortunately, this presumption proved wrong in 1981 when a small population was discovered near Meeteetse, Wyoming. The wild population succumbed to disease a few years later, but not before biologists had taken a few into captivity. Those ferrets formed the basis of a new captive-breeding population that has so far produced more than 6,000 young. Six facilities, including five zoos affiliated with the American Zoological Association, now maintain separate, intensively managed captive ferret populations totaling approximately 240 animals that produce animals for reintroduction into the wild.

Since 1991, more than 2,000 ferrets have been released at 17 sites across the western United States and Mexico. These sites include locations in eight of the 12 states within the species’ historical range. Additional reintroduction efforts are planned for the future, including an effort in Canada in 2009. At present, ferret numbers in the wild total over 1,000 individuals in the fall of each year with perhaps half that many surviving to breed each spring. Although the species will not be recovered until larger numbers of ferrets exist in the wild and routine reintroduction efforts are no longer necessary, we can point to significant progress. Several ferret reintroduction sites are largely self-sustaining, and more animals occur in the wild than in captivity. Still, these milestones collectively result in only about 20 percent of the numbers required to meet the recovery plan goals.

For the past 27 years, many diverse partners have contributed to ferret recovery. The U.S. Fish and Wildlife Service coordinates overall recovery efforts and operates the National Blackfooted Ferret Conservation Center in Colorado, where most captive ferrets are located. The Wyoming Game and Fish Department was instrumental in early captive breeding efforts. This agency and seven of its counterparts have supported reintroduction efforts in their states. Additionally, reintroduction efforts have been supported by the National Park Service, the Bureau of Land Management, the U.S. Forest Service, the Fish and Wildlife Service’s National Wildlife Refuge System, several Native American Tribes, various conservation groups, and private landowners. The Black-footed Ferret Recovery Implementation Team and its predecessors have met routinely for more than 25 years to coordinate recovery efforts.

Some of the most challenging obstacles limiting ferret recovery have been successfully addressed, including the development of captive breeding and field reintroduction techniques. Nevertheless, providing enough quality prairie dog habitat to support a larger number of ferrets in the wild remains problematic. Because many people consider prairie dogs a pest species, these animals remain subject to routine poisoning, which reduces or eliminates potential ferret habitat. Incentive programs to conserve prairie dogs where appropriate and control them in other areas will be necessary to achieve ferret recovery in the working livestock landscape of the western U.S.

 

Additionally, the quality of potential ferret habitat is limited by disease. Sylvatic plague, which was introduced from overseas via flea-infested rats, is lethal to both prairie dogs and ferrets. The recent development of several management tools to ameliorate the impact of this disease has been useful in maintaining some reintroduced ferret populations. More research and field testing of these techniques is underway.

Despite the radically altered environment that reintroduced ferrets face today, the recovery of this species is within reach. All the pieces of the management puzzle necessary to achieve recovery have been identified and have proven successful in the field. The challenge is for continued ferret and prairie dog management efforts to complete the job.

Pete Gober, the project leader of the Black-footed Ferret Recovery Program, can be reached at pete_gober@fws.gov or 605-224-8693, ext. 224.