Not only is the Service elated with the success of this year s increase in captive black-footed ferrets, we also want to recognize the many partners we ve had in working toward this goal, said Wilbur Ladd, Jr., Assistant Regional Director for the Service s ecosystems in North Dakota and South Dakota. Significant contributions made by the zoos, Black-footed Ferret Recovery Foundation, Federal and State government agencies, Tribes, and the National Fish and Wildlife Foundation have been instrumental in accelerating this move toward recovery of the species in the wild, he said. With only about two percent of the species original habitat remaining, recovery of the black-footed ferret, one of North America s rarest mammals, will be a challenge for all partners involved, he added.
Many of the animals produced in the captive breeding facilities during 1996 will be used to continue captive breeding efforts . Approximately 100 young of the year combined with adults already in the program will help maintain a captive population of 240 animals that are three years of age or younger. Reintroduction of ferrets into the wild is being actively pursued this year in three states. About 70 animals will be provided for reintroduction efforts in South Dakota where Service biologists believe there exists the best ferret habitat. Montana will receive fewer ferrets (39), because of reduced habitat due to sylvatic plague near the reintroduction area. Arizona will receive 16 kits for more onsite breeding and rearing.
Cooperating zoos in the black-footed ferret captive breeding effort are part of the American Zoo and Aquariums Association's Species Survival Plan. They include the National Zoo, Washington, D.C.; the Metropolitan Toronto Zoo, Ontario, Canada; the Louisville Zoological Gardens, Kentucky; the Henry Doorly Zoo, Nebraska; the Phoenix Zoo, Arizona; and Cheyenne Mountain Zoological Park in Colorado. Overall recovery goals for the species are guided by the Service's Black-footed Ferret Recovery Plan and include efforts to establish 10 self-sustaining ferret populations at widely scattered geographic locations. To date four reintroduction efforts have occurred and additional reintroductions are anticipated.
Previous reintroduction efforts in Montana and South Dakota in 1994 and 1995 are encouraging. Approximately 20 ferrets are believed to exist at each of these reintroduction sites. These populations include animals born in the wild to parents released from captive breeding facilities. Researchers have documented higher survival rates for ferrets that live in a natural environment prior to release. In response to these findings, recent reintroduction efforts in Arizona explored the value of ferrets being born and reared at a reintroduction site.
The Shirley Basin reintroduction site in Wyoming, that was used from 1991 to 1994, has not fared well. A few ferrets may still survive in this locality, but the number of prairie dogs on which they depend for food has been reduced by the widespread occurrence of sylvatic plague. This disease can also affect ferrets.
The black-footed ferret is a small weasel-like animal which once lived in "towns" occupied by prairie dogs (on which it depends for food) across the western United States. Now the only remaining populations of ferrets that are known to exist in the wild are the result of releases of captive born animals. The ferret declined for several reasons, including the conversion of its grassland habitat to farmland, large scale poisoning efforts of prairie dogs that competed for forage with domestic livestock, and reduction of prairie dog populations by sylvatic plague, an introduced disease to which this species has little immunity.