Black-footed ferrets in South Dakota declined so much that they were assumed extinct, mainly due to the mass extermination of their prey–prairie dogs. Prairie dogs make up about ninety percent of their diet. Ferrets once numbered in the tends of thousands, but habitat destruction, disease and loss of their main food source drove them down to just 18 by 1986. Needless to say, black-footed ferrets were placed on the Endangered Species list. Similarly, prairie dog communities were cut down to just five percent of their original territory.
“Black-footed ferrets were extirpated from the wild in 1987. In 1991, the first ferrets were released back into the wild in Shirley Basin, WY. We now have a total of 19 reintroduction sites, and release 150-250 ferrets per year,” said one of the researchers. (Source: NationalGeographic.com)
With the various rejuvenation efforts over the years, the black footed ferret population has rebounded to about 750-1,000. To be taken off the Endangered Species list there needs to be 1,500 reproducing adults, and ten separate populations inhabiting wild areas of at least 10 acres.
The scientists are about one third of the way to reaching that goal. It isn’t an easy task by any measure. Ferrets that are re-introduced into the wild were grown in captive breeding situations, and then trained to hunt prairie dogs in a controlled environment before release. The land they are released on must have a large enough prairie dog population to sustain the ferrets, because they can each eat one hundred prairie dogs per year. One farmer who owns ten thousand acres of land has allowed prairie dogs on seven thousand of them. So far, just seventy-four ferrets have been released on his property. Black-footed ferrets are the only ferret species native to America. (Domestic ferrets are of European origin.)
Image Credit: Public Domain