In the past three decades very few endangered species have been restored to viable populations. The black footed ferret (Mustela nigripes) was believed to be the most endangered mammal in the united states. It is a small mink sized carnivore of the Great plains and intermountain basins
             The ferrets appear to be obligatory predators on the prairie dogs and once occupied a range essentially identical to that of the prairie dogs. They prey on them and also use their burrows for shelter and nesting. The prairie dogs are considered agricultural pests and competitors with livestock since white settlement first began in the American west. Large scale rodent control programs were implemented by the state and federal governments. They drastically reduced the population of prairie dogs (and other species related to the prairie dog ecosystem) through trapping, gassing and poisoning. These poisoning programs were considered a major cause of the ferret's demise. But, the main cause was the loss of the ferret's prey base and appropriate habitat. Their remaining habitat was fragmented thus leaving the ferret population vulnerable to extinction from various causes including inability to find mates, inbreeding depression, environmental events, and disease of ferrets and their prey.
             The ferrets were believed to be extinct in 1974, but in 1981 a ferret was discovered in Meeteetsee, Wyoming when a ranch dog killed an unusual animal eating from its food dish and the rancher took the carcass to a knowledgeable taxidermist. This was viewed as a rare chance to recover the species. In 1985, a catastrophic disease struck the small ferret population, and most remaining animals were taken into captivity. Captive breeding was initiated, and reintroduction into the wild from the captive population began in 1991.
             The ferret is just one of more than 900 species listed under the Endangered Species act as either threatened or endangered. ...