Once ranged over a large area across the Great Plains/Rocky Mountain states and 1 Canadian province and found on black-tailed prairie dog colonies across the Great Plains from southern Canada to northern Mexico, and on white-tailed and Gunnison's prairie dog colonies across the intermountain west. By 1986 they were completely gone from the wild.
links:
http://wiki.answers.com/Q/Where_do_black_footed_ferrets_live
http://www.emagazine.com/daily-news/poisoning-prairie-dogs#sthash.bLQadb...
Prairie dogs may be a nuisance, but could be kept under control if their predators were not on the cusp of extinction. Poisons that kill prairie dogs is detrimental to the black footed ferrets as the prairie dog is the primary prey. They eat poisoned prairie dogs and ultimately die.
Please help.