Gas drilling is on hold for now in a part of Northwest Colorado that's home to black-footed ferrets.
An internal review board of the Bureau of Land Management has overturned the 2006 sale of oil and gas leases on about 63 thousand acres of ferret habitat.
Environmentalists and the U.S. Fish and Wildlife Service had raised concerns before the auction about the potential impacts on the ferrets.
Black-footed ferrets were thought to be extinct until a small colony was found in Wyoming in the 1980s. The weasel-like animals have been bred in captivity and released in the wild, including in Colorado, to rebuild their populations.