Kit fox

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Kit fox
Vulpes macrotis mutica sitting.jpg
San Joaquin kit fox sitting
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Carnivora
Family: Canidae
Genus: Vulpes
Species:
V. macrotis [2]
Binomial name
Vulpes macrotis [2]
Merriam, 1888
Subspecies
V. m. macrotis
V. m. mutica
Kit Fox area.png
      distribution
Synonyms [2]
  • Vulpes muticus Merriam, 1902
  • Vulpes neomexicanus Merriam, 1903
  • Vulpes arsipus Elliot, 1904
  • Vulpes devius Nelson and Goldman, 1909
  • Vulpes arizonensis Goldman, 1931
  • Vulpes nevadensis Goldman, 1931
  • Vulpes tenuirostris Nelson and Goldman, 1931
  • Vulpes zinseri Benson, 1938

The kit fox (Vulpes macrotis) is a fox species that inhabits arid and semi-arid regions of the southwestern United States and northern and central Mexico. These foxes are the smallest of the four species of Vulpes occurring in North America and are among the smallest of the vulpines worldwide. It has also been called a North American counterpart of the fennec fox due to its large ears. [3]

Contents

Taxonomy

Some mammalogists classify it as conspecific with the swift fox, V. velox, [4] but molecular systematics indicate 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. [3]

Subspecific designations for the species are not fully addressed. As many as eight subspecies have been recognized, [6] although further analyzes have not found support for any subspecies differentiation. [4] However, although there is a clear need for more subspecific clarification, most available data suggest that kit foxes in the San Joaquin Valley of California are likely to warrant a subspecific designation, V. m. mutica, due to geographical isolation, and that any other kit foxes may be included in a second subspecies, V. m. macrotis. [5] [1]

San Joaquin kit fox at the California Living Museum in Bakersfield San Joaquin Kit fox B-40-13 08 20 1993.jpg
San Joaquin kit fox at the California Living Museum in Bakersfield

Subspecies

The endangered San Joaquin kit fox (Vulpes macrotis mutica) was formerly very common in the San Joaquin Valley and through much of Central California. Its 1990 population was estimated to be 7,000. This subspecies is still endangered, after nearly 50 years of being on the Endangered Species List. Officially, this subspecies was listed March 3, 1967. [7] On September 26, 2007, Wildlands Inc. announced the designation of the 684 acre (277 ha) Deadman Creek Conservation Bank, which is intended specifically to protect habitat of the San Joaquin kit fox. [8] However, the population continues to decline mostly due to heavy habitat loss. Other factors include competition from red foxes and the extermination of the wolf from California, which has left the coyote as the dominant meso-predator in kit fox territory, bringing an imbalance in ecosystem relationships. [9] [10]

Appearance

The kit fox is one of the smallest species of the family Canidae found in North America. It has large ears, between 71 and 95 mm (2.8 and 3.7 in), that help the fox dissipate heat and give it exceptional hearing (much like those of the fennec fox). This species exhibits little sexual dimorphism, with the male being slightly larger. The average species weight is between 1.6 and 2.7 kg (3.5 and 6.0 lb). The body length is 455 to 535 mm (17.9 to 21.1 in), with a long tail (about 40% of total length), adding another 260–323 mm (10.2–12.7 in). [11]

The color and texture of the coat vary geographically. In general, the dorsal color is grizzled or yellowish-gray. The grizzled appearance is the result of guard hairs that are typically black-tipped or with two black bands separated by a white band. The guard hairs are less than 50 millimetres (2.0 in) long, and particularly prominent in the middle of the back. The soles of the legs are protected by stiff tufts of hair, a trait that improves traction on loose sandy surfaces as well as protection against extreme temperatures; muzzles and vibrissae are generally black to brown. The tail is bushy and gray, with a black tip, [12] and the caudal gland has a pronounced black spot. [6] Unlike the gray fox, it has no stripe along the length of its tail. Its color ranges from yellow to gray, and the back is usually darker than the majority of its coat; its belly and inner ears are usually lighter. It has distinct dark patches around the nose. [12] The ears are tan or gray on the back, turning to buff or orange at the base. The shoulders, the lower sides, the flanks, and the strip about 25 mm wide across the chest range in color from buffy to orange. [6]

Distribution and habitat

The northernmost part of its range is the arid interior of Oregon. Its eastern limit is southwestern Colorado. It can be found south through Nevada, Utah, southeastern California, Arizona, New Mexico, and into western Texas. [12]

Kit foxes inhabit arid and semi-arid regions encompassing desert scrub, chaparral, halophytic regions, and grasslands. Generally, areas with sparse ground cover are favored. [1] Vegetation habitats vary with the regional fauna, but some examples are sagebrush Artemisia tridentata and saltbrush Atriplex polycarpa. [12] Loose textured soils may be prioritized for denning. Kit Foxes can also be found in agricultural areas, in particular orchards, on a small basis, and can even inhabit urban areas. [1] They are found at elevations of 400 to 1,900 meters (1,300 to 6,200 ft) above sea level. [12]

Behavior

Kit foxes peer from a culvert at a construction site on the Nevada Test Site Kit foxes at the Nevada Test Site.jpg
Kit foxes peer from a culvert at a construction site on the Nevada Test Site

Kit foxes are mostly nocturnal [13] and sometimes crepuscular; [12] they escape heat stress during the day by resting in underground dens. [3] Kit foxes normally forage on their own. Kit foxes are not exceptionally territorial, preferring to live in pairs or small groups of relatives. [12]

Dens are used during the year for daytime resting, escaping predators, avoiding extreme heat, preserving moisture, and carrying and rearing young. [14] Kit Foxes will dig their own dens, but they can also modify and use the burrows of badgers, ground squirrels, prairie dogs, and kangaroo rats. [1] Dens are spread across the home range, and an individual fox usually uses more than 11 dens in a given year. [1] They normally rest in their dens during the day, but sometimes can emerge to bask and, when pups are young, to play. [3]

In comparison to many canids that pants only at the resonant frequency of the thorax, kit foxes pants at a rate proportional to the ambient temperature before the rate exceeds the resonant frequency. In doing so, kit foxes exercise the economics of water at the cost of energy. [6] The apparent velocity of kit foxes is essentially an illusion created by their limited size and cryptic coloration, and their incredible ability to evade and change directions. An accurate account clocked a fox kit at around 40 km/h in front of the car, but the fox was easily exhausted. [6]

Diet

Kit foxes are opportunistic omnivores and scavengers, possibly regulated by prey abundance, [15] but primarily carnivorous. In the Californian deserts, its primary prey is Merriam's kangaroo rat (Dipodomys merriami). [16] Other common prey species include lagomorphs, rodents and insects. Kit foxes also consume birds, reptiles, carrion, fish, and rarely, plant material, such as tomatoes ( Lycopersicon esculentum ), cactus fruits ( Carnegiea gigantea ) and other fruits. Different kit fox families can occupy the same hunting grounds, but do not generally go hunting at the same time. [12] Kit foxes are also known to cache food and eat human food. [15] Black-tailed jackrabbits represent the upper size limit of prey. [3]

Mating and reproduction

San Joaquin kit fox family Vulpes macrotis mutica with pups.jpg
San Joaquin kit fox family

The kit fox is a socially monogamous species, [17] and the mated pair remains together throughout the year. [3] However, polygamous mating relationships have been observed. [14] Female foxes begin searching for natal dens in September and October and usually usable dens are visited and cleaned of debris before the final selection is made. No nest as such is built, but new entrances and tunnels can be added to the den. As with most canids, copulation ends with a "tie" during which the penis is locked in the female's vagina. [6] [18]

Females are monoestrous. Male and female kit foxes usually establish mating pairs during October and November, and they mate from December to January-February. Gestation lasts probably around 49–56 days, and the litters are born in February or March; litter size is usually four or five, and the sex ratio is roughly even. They do not emerge from the den until they are at least four weeks old, and are weaned after about eight weeks and become independent at five to six months old. They become sexually mature at 10 months. Both parents take part in raising and protecting their young. Pups emerge from the den at about one month of age and spend several hours each day playing outside the entrance. The male seems to do most of the hunting during this period, and later, both parents provide food until the pups start to forage with them at three to four months of age. [6] [3]

Survival and mortality rates of kit foxes can vary significantly year to year. In captivity, they have lived 10 to 12 years; [19] while the average lifespan of a wild kit fox is 5.5 years. [12] One Californian study of 144 kit fox pups showed a 74% mortality rate in pups within the first year. [19]

Related Research Articles

<span class="mw-page-title-main">Arctic fox</span> Species of fox

The Arctic fox, also known as the white fox, polar fox, or snow fox, is a small species of fox native to the Arctic regions of the Northern Hemisphere and common throughout the Arctic tundra biome. It is well adapted to living in cold environments, and is best known for its thick, warm fur that is also used as camouflage. It has a large and very fluffy tail. In the wild, most individuals do not live past their first year but some exceptional ones survive up to 11 years. Its body length ranges from 46 to 68 cm, with a generally rounded body shape to minimize the escape of body heat.

<span class="mw-page-title-main">Coyote</span> Species of canine native to North America

The coyote, also known as the American jackal, prairie wolf, or brush wolf, is a species of canine native to North America. It is smaller than its close relative, the gray wolf, and slightly smaller than the closely related eastern wolf and red wolf. It fills much of the same ecological niche as the golden jackal does in Eurasia; however, the coyote is generally larger.

<span class="mw-page-title-main">Fox</span> Genera of mammal

Foxes are small-to-medium-sized omnivorous mammals belonging to several genera of the family Canidae. They have a flattened skull; upright, triangular ears; a pointed, slightly upturned snout; and a long, bushy tail ("brush").

<span class="mw-page-title-main">Fennec fox</span> Species of fox

The fennec fox is a small crepuscular fox native to the deserts of North Africa, ranging from Western Sahara and Mauritania to the Sinai Peninsula. Its most distinctive feature is its unusually large ears, which serve to dissipate heat and listen for underground prey. The fennec is the smallest fox species. Its coat, ears, and kidney functions have adapted to the desert environment with high temperatures and little water. It mainly eats insects, small mammals and birds. The fennec has a life span of up to 14 years in captivity and about 10 years in the wild. Its main predators are the Verreaux's eagle-owl, jackals and other large mammals. Fennec families dig out burrows in the sand for habitation and protection, which can be as large as 120 m2 (1,300 sq ft) and adjoin the burrows of other families. Precise population figures are not known but are estimated from the frequency of sightings; these indicate that the fennec is currently not threatened by extinction. Knowledge of social interactions is limited to information gathered from captive animals. The fennec's fur is prized by the indigenous peoples of North Africa, and it is considered an exotic pet in some parts of the world.

<i>Vulpes</i> Genus of the sub-family Caninae

Vulpes is a genus of the sub-family Caninae. The members of this genus are colloquially referred to as true foxes, meaning they form a proper clade. The word "fox" occurs in the common names of all species of the genus, but also appears in the common names of other canid species. True foxes are distinguished from members of the genus Canis, such as domesticated dogs, wolves, jackals and coyotes, by their smaller size (5–11 kg), longer, bushier tail, and flatter skull. They have black, triangular markings between their eyes and nose, and the tip of their tail is often a different color from the rest of their pelt. The typical lifespan for this genus is between two and four years, but can reach up to a decade.

<span class="mw-page-title-main">Island fox</span> Species of fox

The island fox is a small fox species that is endemic to six of the eight Channel Islands of California. There are six subspecies, each unique to the island it lives on, reflecting its evolutionary history. They are generally docile, show little fear of humans, and are easily tamed. Island foxes played an important role in the spiritual lives of native Channel Islanders. They have been likely semi-domesticated as pets, used as pelts, or for other functions, like pest control.

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<span class="mw-page-title-main">Swift fox</span> Species of mammal

The swift fox is a small light orange-tan fox around the size of a domestic cat found in the western grasslands of North America, such as Montana, Colorado, New Mexico, Kansas, Oklahoma and Texas. It also lives in southern Manitoba, Saskatchewan and Alberta in Canada, where it was previously extirpated. It is closely related to the kit fox and some mammalogists classify them as conspecific. However, molecular systematics imply that the two species are distinct. Interbreeding between the two species does occur where their ranges overlap, but this hybridization is quite restricted in scope.

<span class="mw-page-title-main">Bengal fox</span> Species of carnivore

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<span class="mw-page-title-main">Cape fox</span> Species of carnivore

The Cape fox, also called the asse, cama fox or the silver-backed fox, is a small species of fox, native to southern Africa. It is also called a South African version of a fennec fox due to its similarly big ears. It is the only "true fox" occurring in sub-Saharan Africa, and it retains primitive characteristics of Vulpes because it diverged early in the evolutionary history of the group.

<span class="mw-page-title-main">Gray fox</span> Species of canid

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<span class="mw-page-title-main">Tibetan fox</span> Species of true fox

The Tibetan fox, also known as the Tibetan sand fox, is a species of true fox endemic to the high Tibetan Plateau, Ladakh plateau, Nepal, China, Sikkim, and Bhutan, up to elevations of about 5,300 m (17,400 ft). It is listed as Least Concern in the IUCN Red List, on account of its widespread range in the Tibetan Plateau's steppes and semi-deserts.

<span class="mw-page-title-main">Blanford's fox</span> Species of carnivore

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<span class="mw-page-title-main">San Joaquin antelope squirrel</span> Species of rodent

The San Joaquin antelope squirrel or Nelson's antelope squirrel, is a species of antelope squirrel, in the San Joaquin Valley of the U.S. state of California.

<span class="mw-page-title-main">Corsac fox</span> Species of carnivore

The corsac fox, also known simply as a corsac, is a medium-sized fox found in steppes, semi-deserts and deserts in Central Asia, ranging into Mongolia and northern China. Since 2004, it has been classified as least concern by IUCN, but populations fluctuate significantly, and numbers can drop tenfold within a single year. It is also known as the steppe fox. The word "corsac" is derived from the Russian name for the animal, "korsák" (корса́к), derived ultimately from Turkic "karsak".

<span class="mw-page-title-main">Pale fox</span> Species of carnivore

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<span class="mw-page-title-main">Rüppell's fox</span> Species of carnivore

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<span class="mw-page-title-main">Red fox</span> Species of mammal

The red fox is the largest of the true foxes and one of the most widely distributed members of the order Carnivora, being present across the entire Northern Hemisphere including most of North America, Europe and Asia, plus parts of North Africa. It is listed as least concern on the IUCN Red List. Its range has increased alongside human expansion, having been introduced to Australia, where it is considered harmful to native small and medium-sized rodents and marsupials. Due to its impact on native species, it is included on the list of the "world's 100 worst invasive species".

<span class="mw-page-title-main">San Joaquin kit fox</span> Species of fox

The San Joaquin kit fox is an endangered species of fox that was formerly very common in the San Joaquin Valley and much of Central California. As an opportunistic hunter, the San Joaquin kit fox primarily preys on kangaroo rats but also targets white-footed mice, pocket mice, ground squirrels, rabbits, and ground-nesting birds. During certain times of the year, especially when other food sources might be scarce, it will also consume insects. Its 1990 population was estimated to be 7,000. This subspecies is still endangered, after nearly 50 years of being on the Endangered Species List. Officially this subspecies was listed March 3, 1967. On September 26, 2007, Wildlands Inc. announced the designation of the 684-acre (2.77 km2) Deadman Creek Conservation Bank, which is intended specifically to protect habitat of the San Joaquin kit fox. However, the population continues to decline mostly due to heavy habitat loss. Other factors include competition from red fox, and the extermination of the gray wolf from California has left the coyote as the dominant meso-predator in kit fox territory bringing an imbalance in ecosystem relationships. Sarcoptic mange has also constituted a significant threat, specifically to the Bakersfield population of the subspecies, with 15 confirmed cases reported by the end of 2014.

References

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