Montana Field Guide

Swift foxes are small, weighing 1.8 to 3.0 kilograms, with males averaging larger than females. The winter pelage is dark buffy-gray above, and orange-tan on the sides, legs, and lower surface of the tail. The chest and belly are buff to white and the tail is tipped with black. In summer the coat is shorter, harsher, and more reddish. The length of the head and body is 38 to 53 centimeters and tail length is 23 to 35 centimeters. The length of the ear of adults is 56 to 78 millimeters (Nowak 1991, Clark and Stromberg 1987).

Swift fox are not migratory.

Swift fox inhabit open prairie and arid plains, including areas intermixed with winter wheat fields in north-central Montana. They use burrows when they are inactive; either dug by themselves or made by other mammals (marmot, prairie dog, badger). The burrows are usually located in sandy soil on high ground such as hill tops (Pruss 1999) in open prairies, along fencerows, or occasionally in a plowed field. An individual may use several different dens throughout the year. A statewide assessment of swift fox habitat was conducted by the Department of Fish, Wildlife, and Parks in May 1994 to identify large blocks of prairie grassland. Suitable swift fox habitat was generally defined as extensive in size (preferably over 100,000 acres), with relatively level topography, and with greater than 50% of the area undisturbed by agriculture. A total of 8,000,000 suitable acres were identified in Montana (Giddings and Knowles 1995).

The diet in Montana is not known, but studies from other areas suggest the diet includes mammals (jack rabbits, cottontails, ground squirrels, mice), birds, invertebrates, and vegetable matter (grasses and berries). Mammals (often especially cottontail rabbits) and insects comprise the bulk of the diet, but feeding is opportunistic. Swift fox cache excess food under snow in winter (Banfield 1974).

Mortality factors for swift fox are poorly known. Coyotes, and formerly wolves, are suspected predators (Egoscue 1979). Dispersal distance averages around 11 kilometers, with an observed maximum of only 64 kilometers (Mercure et al. 1993). Swift fox may range over several square kilometers during a single night. Density of a locally abundant population in Wyoming was reported as one pair per 5 to 8 square kilometers (Clark and Stromberg 1987).

Swift fox were very susceptible to trapping and poisoning for wolves and coyotes in the early 1900s (Hoffmann and Pattie 1968). These practices have been discontinued, but the ecological community of the grassland environment may nonetheless be in an altered state, with the niche once occupied by swift fox restricted by decreased prey availability or increased competition with coyotes (Giddings and Knowles 1995). Swift fox are considered to be an active disperser and states and provinces adjacent to Montana should be recognized as natural sources of dispersing animals.

There is no information specific to Montana but information from other areas suggests they breed in late winter. Gestation lasts probably 7 or 8 weeks. In Oklahoma, most litters are born in March or early April. Litter size usually is 3 to 6 (Egoscue 1979). Swift foxes produce one litter per year and young are born in an underground den about 1 meter below the ground surface (Banfield 1974). Dens usually have multiple entrances and may be 3 to 6 meters long. Disturbance may cause the female to move young to a different den. Pups first emerge from the den at about 1 month of age (by June 1 in Wyoming). Young are tended by both sexes and disperse in late summer to early fall. Pair-bonds may be life-long.

Swift fox were thought to be common on the eastern plains of Montana in the early 1900's but were exterminated and believed to be extinct in the state by 1969 (Hoffmann et al. 1969). Sporadic observations throughout eastern Montana have been recorded since 1969 and reintroductions of swift fox on the Blackfoot Indian Reservation in northwestern Montana in 1998 (Foresman 2001) and in southern Saskatchewan and Alberta from 1983 to 1991 are thought to be the source of many of these sightings. These populations continue to expand to the south and east in Montana. Recent surveys in Montana have documented swift fox in many of the counties bordering Canada in north-central Montana (Moehrenschlager and Moehrenschlager 2001). The trapping season for Montana is closed and swift fox are not legally trapped in Montana. Trappers that accidentally trap a swift fox must release it uninjured or if the fox cannot be released uninjured the trapper must contact Montana Fish, Wildlife and Parks immediately.