Swift foxes originally ranged from the plains of western Canada and across the Great Plains of North America to Texas. Swift foxes disappeared entirely from Canada in the 1930s, but have been reintroduced there. At present there are a few scattered populations of swift foxes in the Great Plains of the U.S. and in western Canada. The largest population is in Colorado, Kansas, New Mexico, and Wyoming, where the species is stable. There are currently approximately only 350 individuals located in Southeast Alberta and Southwest Saskatchewan.

Biogeographic Regions: nearctic (Native )

occurs (regularly, as a native taxon) in multiple nations

Canada

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: (20,000-2,500,000 square km (about 8000-1,000,000 square miles)) Historical range included the central plains of North America, from southern Alberta and Saskatchewan south to northern Texas: included all or portions of North Dakota, South Dakota, Montana, Nebraska, Wyoming, Colorado, Kansas, Oklahoma, New Mexico, Texas, and the souther regions of Alberta, Manitoba, and Saskatchewan (Hall and Kelson 1959, Egoscue 1979, Banfield 1974). Present range is now much restricted; the species is nearly continuously distributed from Wyoming south throughout eastern Colorado, western Kansas, the Oklahoma Panhandle, eastern New Mexico, and part of the extreme northern panhandle of Texas, with scattered, disjunct populations in Montana, South Dakota, and Nebraska; apparently extirpated in North Dakota (USFWS 2001). The species was extirpated in Canada (1978 COSEWIC report), but reintroduction has resulted in reestablishment of a wild population, though viability of this population is in question. Present zone of contact between V. velox and V. macrotis is approximately in the area of the Pecos River (Dragoo et al. 1990).

The swift fox is the smallest of the wild dogs in North America. Adults weigh between 2 and 3 kilograms and are approximately 30 cm tall and 80 cm long. They are about the size of a domestic cat. Males and females look similar except that males are slightly larger. The fur of V. velox is light grey with orange-tan coloring on the sides and legs. The throat, chest, underside and inside of the ears are creamy white. The tail is bushy and marked with black at the tip. There are also black patches on either side of the snout.

Range mass: 2 to 3 kg.

Other Physical Features: endothermic ; homoiothermic; bilateral symmetry

Sexual Dimorphism: male larger

Average basal metabolic rate: 4.948 W.

Length: 80 cm

Weight: 2700 grams

Differs from the kit fox in smaller ears, broader snout, and shorter tail (see Nowak 1991).

• Terrestrial

Swift foxes live primarily in shortgrass prairies and deserts. They often form their dens in sandy soils on open prairies, along fences or in plowed fields.

Habitat Regions: temperate ; terrestrial

Terrestrial Biomes: desert or dune ; savanna or grassland

Comments: Habitat includes open prairie and arid plains, including areas intermixed with winter wheat fields. In Texas, swift foxes selected only shortgrass prairies and had lower-than-expected use or completely avoided non-native grasslands enrolled in the Conservation Reserve Program, irrigated agricultural fields, and dryland agricultural fields (Kamler et al. 2003). Viable populations exist in shortgrass prairie-sagebrush steppe transition habitat in southeastern Wyoming (Olson and Lindzey 2002).

Dens are in burrows. A fox may dig a burrow or use a burrow made by another mammal (e.g., marmot, prairie dog, badger), usually in sandy soil on high ground (e.g., hill top, Pruss 1999) in open prairies, along fencerows, occasionally in plowed field. An individual may use several different dens throughout the year.

Young are born in an underground den about 1 meter below the ground surface (Banfield 1974). The den usually has multiple entrances and may be 3-6 meters long. Slight disturbance may cause a female to move her young to a different den.

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

Home range size ranges from a few hundred to a few thousand hectares (see Harrison 2003). Individuals may range over several square kilometers during a single night; may shift the location of their home range from one year to the next (Harrison 2003). Dispersal distance averages around 11 km, with an observed maximum of only 64 km (see Mercure et al. 1993).

The diet of the swift fox varies seasonally, depending on what is available. It typically eats whatever live prey it can catch. Its diet includes small mammals, birds, reptiles, amphibians, fish, insects, but also includes berries and grasses.

Animal Foods: birds; mammals; amphibians; reptiles; fish; eggs; carrion ; insects; terrestrial non-insect arthropods

Plant Foods: seeds, grains, and nuts; fruit

Primary Diet: omnivore

Comments: Diet includes mammals (jackrabbits, cottontails, ground squirrels, mice), birds, invertebrates, and vegetable matter (grasses and berries). Mammals (often especially Sylvilagus) and insects comprise the bulk of the diet, but feeding is opportunistic. Caches excess food under snow in winter (Banfield 1974).

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: 21 - 80

Comments: This species is represented by a fairly large number of extant occurrences (subpopulations), but the precise number is unknown.

2500 - 1,000,000 individuals

Comments: Total adult population size is unknown but likely is at least several thousand. See Allen et al. (1995) for a good review of state by state status.

Mortality factors are poorly known. Coyotes, and formerly wolves, are suspected predators (Egoscue 1979).

Olson and Lindzey (2002) estimated annual survival rates of swift foxes (Vulpes velox) in a transition zone between shortgrass prairie and sagebrush steppe plant communities in southeastern Wyoming during 1996-2000. Annual adult survival ranged from 40% to 69%, with predation by coyotes (Canis latrans) the primary cause of deaths. Two foxes died of canine distemper virus. Adult survival was similar and litter size slightly larger than observed elsewhere in the species range, suggesting that viable swift fox populations can be supported by sagebrush steppe and shortgrass prairie transition habitat.

Density of a locally abundant population in Wyoming was reported as one pair per 5-8 sq km (Clark and Stromberg 1987).

Comments: Primarily nocturnal, may rest in sun outside burrow during day.

Swift foxes usually live between 3 and 6 years in the wild, but may live up to 14 years in captivity.

Range lifespan

Status: wild: 3 to 6 years.

Range lifespan

Status: captivity: 14 (high) years.

Average lifespan

Status: captivity: 12.0 years.

Average lifespan

Status: captivity: 12.8 years.

Individuals sometimes pair for life, but may not necessarily mate with the same partner each year.

Mating System: monogamous

Male swift foxes mature and mate at one year, while females may wait until their second year before breeding. The breeding season for individuals in Canada begins in March. The gestation period is 50-60 days and pups are born in mid-May. The breeding season for individuals farther south in the United States begins in late December, early January, with pups born in March and early April.  Swift foxes have only one litter annually, with a litter size ranging anywhere from 2 to 6.

Breeding interval: Breeding occurs yearly.

Breeding season: The breeding season begins from December through March.

Range number of offspring: 2 to 6.

Average number of offspring: 4.25.

Range gestation period: 50 to 60 days.

Range weaning age: 42 to 49 days.

Average time to independence: 6 months.

Average age at sexual or reproductive maturity (female): 2 years.

Average age at sexual or reproductive maturity (male): 1 years.

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); viviparous

Average birth mass: 39.65 g.

Average number of offspring: 4.5.

Average age at sexual or reproductive maturity (male)

Sex: male: 365 days.

Average age at sexual or reproductive maturity (female)

Sex: female: 365 days.

Pups are born in the underground den and typically remain there for about one month. After birth, the eyes and ears of the pups remain closed for 10 to 15 days, thus leaving them dependent on the mother for food and protection. Pups are weaned when 6 to 7 weeks old but usually remain with the mother and father until the fall.

Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female); pre-weaning/fledging (Provisioning: Male, Female, Protecting: Male, Female); pre-independence (Provisioning: Male, Female, Protecting: Male, Female); extended period of juvenile learning

Breeds in late winter. Gestation lasts probably 7-8 weeks. In Oklahoma, most litters are born in March or early April. Litter size usually is 3-6, mean 4-5 (Egoscue 1979, Olson and Lindzey 2002). Produces one litter per year. Pups first emerge from den at about 1 month (by 1 June in Wyoming). Young are tended by both sexes, disperse in late summer-early fall. Pair-bond may be life-long.

In southeastern Wyoming, 19 of 24 (79%) swift fox pairs were observed with young over 3 years (Olson and Lindzey 2002).

The swift fox is a severely endangered species. It has faced habitat losses due to agricultural, industrial and urban development. Hundreds of swift foxes were killed accidentally during the early 1930s from predator control programs aimed at removing wolves, coyotes, and ground squirrels from prairies. In 1978, the species was declared extirpated in Canada. There are currently populations of swift foxes in the U.S. ranging from South Dakota to Texas. However, the population is stable only in the central part of the range. Reintroduction programs in Western Canada have established small populations in southeast Alberta and southwest Saskatchewan, totaling 350 foxes. The current goal of reintroduction programs in Canada is to establish a viable, self-sustaining population distributed across the prairies and to remove the species from the endangered category by the year 2000.

Several things can be done to try to prevent further loss of and to encourage repopulation of swift foxes. Preserving the habitats of the foxes is crucial. Also, captive breeding could help increase the number of swift foxes. Reintroduction programs, like the ones in western Canada, may also be successful in restoring the swift fox to its natural habitat. However, a large number of reintroduced individuals do not survive their first year in the wild for one reason or another. Therefore, populations must be monitored and protected from human harm. Even though it is illegal to kill swift foxes, they are sometimes mistaken as coyotes and killed.

US Federal List: endangered

CITES: no special status

IUCN Red List of Threatened Species: least concern

Canada

Rounded National Status Rank: N1 - Critically Imperiled

United States

Rounded National Status Rank: N3 - Vulnerable

Rounded Global Status Rank: G3 - Vulnerable

Reasons: The swift fox has disappeared from about 60% of its former range. It is still widespread in the central United States and relatively common in some areas, but declining/scarce in other areas. Some reintroduction efforts have been successful, and increases have been noted in states such as Montana. Threats include habitat loss and degradation, interspecific competiton with red fox and coyote, vehicle collisions, and others; more information on population trends and threats is needed.

Environmental Specificity: Narrow. Specialist or community with key requirements common.

Comments: Swift foxes are more specialized than other North American canids (Kamler et al. 2003).

Global Short Term Trend: Relatively stable to increase of 25%

Comments: There is evidence that some reoccupation of former range is occurring in Montana, Oklahoma, Kansas, Colorado, and Wyoming (J. Carlson, pers. comm., USFWS, Federal Register, 16 June 1995). In general, population trend is poorly known in most areas.

Global Long Term Trend: Decline of 50-70%

Comments: Declines occurred in the late 1800s and early 1900s. The species made a limited comeback in portions of the historical range in the mid-1950s. It now occupies about 40% of the historical range (USFWS 2001).

Degree of Threat: B : Moderately threatened throughout its range, communities provide natural resources that when exploited alter the composition and structure of the community over the long-term, but are apparently recoverable

Comments: Reasons for decline include loss of habitat to agriculture and mineral extraction, habitat fragmentation, habitat degradation due to control of colonial rodents, predation and interspecific competiton (with coyote and red fox), and collisions with automobiles (e.g., when feeding on carrion). This species is easily shot, trapped, and poisoned, hence susceptible to mortality from predator and rodent control (Uresk and Sharps 1986). Overall trapping pressure has been reduced over the past few decades; no longer a limiting factor (USFWS 2001). Interspecific competition may be an especially important limiting factor but more research is needed. In Texas, vehicle collisions (42 percent of deaths) and coyote predation (33 percent) were the primary causes of death (Kamler et al. 2003).

Management Requirements: See Kahn et al. (1996).

Global Protection: Unknown whether any occurrences are appropriately protected and managed

Comments: Seventy to seventy-five percent of remaining populations are on private lands; the remainder are on federal lands managed by various agencies.

Needs: Large areas not subject to rodent/rabbit/insect/predator control should be protected.

The cost of captive breeding programs and monitoring after reintroduction can often be high.

In the past, the fur of the swift fox was a valued commodity.

Comments: Legally harvested in Colorado, New Mexico, Kansas, and Texas.

Comments: Vulpes macrotis is here treated as a species separate from V. velox.

Vulpes macrotis (kit fox) was regarded as conspecific with V. velox (swift fox) by Dragoo et al. (1990) (conclusion based mainly on protein-electrophoretic study) and some previous authors. Jones et al. (1992) and Wozencraft (in Wilson and Reeder 1993) concurred in treating velox and macrotis as conspecific. Dragoo et al. (1990) included macrotis as a subspecies of V. velox; other nominal subspecies were regarded as unworthy of recognition.

Mercure et al. (1993) examined mtDNA variability in 10 areas throughout most of the range of the kit and swift foxes; they concluded that kit and swift foxes hybridize over a limited geographic area and should be recognized as separate species; they suggested that the San Joaquin Valley population, though not very distinctive, be recognized as a subspecies because, relative to variation within kit foxes, it appeared as the most distinct single phylogeographic unit and is an isolated population; mtDNA data did not support any of the other 10 subspecific designations of kit and swift fox (Hall 1981). The mammal lists by Baker et al. (2003) and Wozencraft (in Wilson and Reeder 2005) followed Mercure et al. (1993) in recognizing V. macrotis and V. velox as distinct species.

See Dragoo and Wayne (2003) for a review of the systematics of these foxes.