| Swift fox[1] | |
|---|---|
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| Swift fox at Colorado Wolf and Wildlife Rescue Center | |
Scientific classification | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Mammalia |
| Order: | Carnivora |
| Family: | Canidae |
| Genus: | Vulpes |
| Species: | V. velox |
| Binomial name | |
| Vulpes velox (Say, 1823) | |
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| Swift fox range | |
| Synonyms | |
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Theswift fox (Vulpes velox) is a small light orange-tanfox around the size of adomestic cat found in the western grasslands ofNorth America, such asMontana,Colorado,New Mexico,Kansas,Oklahoma[3] andTexas.[1] It also lives in southernManitoba,Saskatchewan andAlberta inCanada, where it was previouslyextirpated.[2] It is closely related to thekit fox (V. macrotis) and some mammalogists classify them asconspecific.[4] However, molecular systematics imply that the two species are distinct.[5] Interbreeding between the two species does occur where their ranges overlap (eastern New Mexico and western Texas), but this hybridization is quite restricted in scope.[6]
The swift fox lives primarily in short-grass prairies and deserts. It became nearly extinct in the 1930s as a result of predator control programs, but was successfully reintroduced later. Currently, the conservation status of the species is considered by theIUCN asLeast Concern owing to stable populations elsewhere.[2]
Like most canids, the swift fox is anomnivore, and its diet includes grasses andfruits as well as small mammals,carrion, and insects. In the wild, its lifespan is 3 to 6 years, and it breeds once annually, from late December to March, depending on the geographic region. Pups are born anywhere from March to mid-May, and are weaned at six to seven weeks old.
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The swift fox has a dark, grayish, tan coloration that extends to a yellowish tan color across its sides and legs. The throat, chest, and belly range from pale yellow to white in color. Its tail is black-tipped, and it has black patches on its muzzle. Its ears are noticeably large, like those of thekit fox, although slightly farther apart than on the head of the latter. It is about 12 inches (30 cm) in height, and 31 inches (79 cm) long, measuring from the head to the tip of the tail, or about the size of a domestic cat. Its weight ranges from around five to seven pounds.[7] Males and females are similar in appearance, although males are slightly larger.[8]
The swift fox lives in short-grass prairies and western grassland. They form theirdens in sandy soil on open prairies, in plowed fields, or along fences.[8] It is native to theGreat Plains region of North America, and its range extends north to the southernAlberta andSaskatchewan, Canada, and south toTexas. It reaches from westernIowa toColorado,Kansas,Wyoming,Nebraska, andMontana.[7]
The swift fox was once a severelyendangered species, due to predator control programs in the 1930s that were aimed mostly at thegray wolf and thecoyote.[8] The species wasextirpated from Canada by 1938,[2] but a reintroduction program started in 1983[9] has been successful in establishing small populations in southeastAlberta and southwestSaskatchewan, despite the fact that many reintroduced individuals do not survive their first year.[8] Nonetheless, by 1996, 540 foxes had been released around the Alberta-Saskatchewan border andMilk River Ridge areas, parts of the species' original native range.[10] Four years later, those introduced foxes had tripled in number, making the program one of the most successful endangered species reintroduction programs in the world.[11] In May 1999, theSpecies at Risk Act listed the swift fox as anendangered species in Canada, giving the species further protection for growth.[12] A small, but stable and growing population continues to live freely in the southeastern regions of Alberta, and southwestern regions of Saskatchewan.[10] Canada's national recovery strategy plan was revised in 2008 by the National Swift Fox Recovery Team, with projections of a long-term goal by 2026, "to restore a self-sustaining swift fox population of 1,000 or more mature, reproducing foxes that does not experience greater than a 30% population reduction in any 10-year period".[2]
Exact population numbers of the swift fox are unknown, but it is known that they currently inhabit only 40% of their historic range.[7] In addition to its populations in Canada, there are also swift fox populations in the United States, ranging fromSouth Dakota to Texas. In 1995, theU.S. Fish and Wildlife Service determined that the fox warranted an endangered listing, but other higher priority species precluded its listing.[13] This prompted state wildlife agencies within the fox's range to create the Swift Fox Conservation Team, which worked to implement better swift fox management and monitoring programs.[13] Populations in the United States are stable in the central part of its range,[8] and it is not considered endangered in the United States. TheIUCN Red List characterizes it as of Least Concern.[2]
In the wild, the swift fox usually lives 3–6 years, but may live up to 14 years in captivity.[10] It is primarilynocturnal, spending only evenings and nighttime above ground in the summer. Daytime activities are usually confined to the den, but it has been known to spend the warm midday period above ground during the winter.[8] Due to the harsh winter conditions where the swift fox can be found, there is an increase in mortality rates.[14] The swift fox is more heavily dependent on itsden than most North Americancanids, using them as shelter from predators. These dens are usually burrows that are two to four meters in length.[8] It has been known to run very fast, at speeds of over 50 km/h (30 mph).[8] or up to 60 km/h (40 mph)[15] Thecoyote is the swift fox's main predator, but at times chooses not to consume the swift fox, killing it more often as competition than as prey.[16] Other predators include theAmerican badger,golden eagle, andbobcat.[16] It is also vulnerable to trapping and poisoning, as well as death on highways.[17]
Swift foxes are asocially monogamous species, although multiple breeding strategies have been observed.[18] The adult swift fox'sbreeding season varies with region. In the southern United States, it mates between December and February with pups born in March and early April, while in Canada, the breeding season begins in March, and pups are born in mid-May. The male swift fox matures and may mate at one year, while the female usually waits until her second year before breeding. Adults live in pairs, and although some individuals mate for life, others choose different partners each year. Gestation takes around 51 days, and four to five kits are born.[7][8]
The swift fox only has one litter annually, but may occupy up to thirteen dens in one year, moving because prey is scarce or because skinparasites build up inside the den. Sometimes it makes other burrows from other bigger animals, even though it is completely capable of digging one on its own. Pups are born in the den and typically remain there for approximately one month. A newborn pup's eyes and ears remain closed for ten to fifteen days, leaving it dependent on the mother for food and protection during this time. It is usually weaned around six or seven weeks old and remains with its parents until fall.[8] Recent research has shown that social organization in the swift fox is unusual among canids, since it is based on the females.[19] Females maintainterritories at all times, but males emigrate if the resident female is killed or removed.[19]
Like most foxes, the swift fox is anomnivore.Rabbits,mice,ground squirrels,birds,insects, otherarthropods,lizards,amphibians,fish andeggs are staples.[7][8]Grasses andfruits round out its diet.[8] However, like any efficient forager, the swift fox takes advantage of seasonal foods.[8] During the summer, adults eat large amounts of insects, includingbeetles andgrasshoppers, and feed their young with larger prey items.[citation needed]Deer and other carrion killed by other animals may also be important food sources.[citation needed]
