The black-footed ferret will travel an average of about 11 miles to find prairie dogs, but due to farmers, this is becoming virtually impossible. The black-footed ferret has become an endangered species because their main food source, the prairie dog, is being eliminated by farmers and ranchers. I’m now going to tell you how and why the black-footed ferret is endangered. First, the black-footed ferret used to live from Canada to Mexico in the Great Plains. Now, they only inhabit eight different states in the United States, Canada, and Mexico. Second, the ferrets almost went extinct in the 1900s, and by 1986 there were only 18 left in the wild. Finally, black-footed ferrets and prairie dogs are getting diseases that are killing both species.