Black-footed Ferrets Make a Comeback
The North American Mustelids Return from Near Extinction
Aug 15, 2008 Scottie V. Westfall
Black-footed ferrets once ranged from the short-grass prairies of Canada south to the northern parts of Mexico. The ferrets were dependent upon prairie dogs for their sustenance, and they used prairie dog burrows as their dens. The black-footed ferret’s dependence on the large ground squirrels proved to be its downfall. When these areas opened for settlement, ranchers saw the prairie dogs as competitors with their domestic cattle for grass.
The prairie dogs were shot, trapped, and poisoned. Their burrows were destroyed. The ferrets soon found themselves without an adequate food source and without dens. Some ferrets were also taken in the process of killing the prairie dogs. The prairies were converted to cropland, further displacing prairie dog towns and black-footed ferrets. To make matters worse, canine distempter, an introduced disease and sylvatic plague, also began to spread amongt the ferrets. As a result of these pressures, the number of ferrets plummeted.
Extinct in the Wild by 1986
The black-footed ferret was considered endangered in 1967, and the last known wild population went extinct in 1974. However, a dog killed a ferret near Meeteetse, Wyoming in 1981, and subsequent study found that this ferret came from a population of about 130 ferrets. Distempter soon spread through this ferret colony, and by 1986, only 18 individuals were left. These 18 were captured and placed into a captive breeding program.
Captive Breeding Program
The US Fish and Wildlife Service, the Wyoming Game and Fish Department, and the Association of Zoos and Aquariums orchestrated the captive breeding program. The main breeding facility was at Wheatland, Wyoming, but other facilities were chosen to house breeding populations. The ferrets had already suffered severe epidemics of distemper in which whole colonies of ferrets were decimated. If the distemper virus or some other pathogen infected the Wheatland facility, the last remaining black-footed ferrets could be destroyed.
Reintroduction
By 1991, there were enough ferrets in captivity to consider reintroducing them to the wild. Using private and public lands, the ferrets were reintroduced to parts of Wyoming and South Dakota. Since then, the ferrets have been reintroduced to Arizona, Montana, Colorado, Utah, and Kansas. The ferrets are released as young adults that are “preconditioned” to natural burrows and prairie dog meat before their release. This preconditioning occurs in outdoor pens, which give the ferrets a chance to become accustomed to wild conditions before their release.
Successful Wild Populations
Today, it is estimated that 750 black-footed ferrets now live in the wild, feeding on prairie dogs and residing in prairie dog burrows. The ferrets and prairie dogs now live in small tracts of land, set aside by state and federal organizations and private individuals for conservation. The prairies have largely been turned over to pasture and crop land, and very little room exists for the massive prairie dog towns that once dotted this land. Black-footed ferrets may have been saved from extinction, but the ecosystem in which they once lived is forever scarred. These conservation areas are mere reminders of what the prairie once was.
Sources:
Defenders of Wildlife's Black-Footed Ferret
Black-footed Ferret Conservation Program
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