In 1979, the last known living black-footed ferret died in captivity. The species was thought be be extinct. Following a miraculous discovery of one lone ferret colony in Wyoming in 1981, a decades-long effort began to save the most endangered mammal in North America. The Fort Belknap Reservation in Montana is one of the battlegrounds in the attempt to recover the species. With the help of conservation organizations including Defenders of Wildlife and the World Wildlife Fund, the goal of the Gros Ventre and Assininboine Tribes of Fort Belknap is not only to save the ferret, but to establish and reclaim a lost vestige of the American Great Plains, with the full compliment of animals—bison, prairie dogs, ferrets, and other prairie species. If they are successful, they will have created a fully-functioning natural prairie ecosystem in north-central Montana.