The swift fox is another species that takes refuge in the prairie soil. "Their tallons appear longer than any species of fox I ever saw and seem therefore prepared more amply by nature for the purpose of burrowing," Lewis wrote in his description of the small canine. The northern variety (Vulpes velox hebes) has been particularly affected by changes in the prairie composition since settlement. In 1995, the U.S. Fish and Wildlife Service determined that an endangered-species listing for the swift fox was warranted, but that other species were a higher priority. The Blackfeet tribe has launched a reintroduction program on a reservation outside Glacier National Park and has released almost 100 foxes since 1998.

Federal candidate, state threatened.