Predation by coyotes (Canis latrans) accounts for over 75% of kit fox predation. Other predators include bobcats (Lynx rufus), red foxes (Vulpes vulpes), American badgers (Taxidea taxus), feral dogs (Canis lupus familiaris), and large raptors (Accipitridae). Also kit fox deaths have been due to interactions with humans, such as illegal hunting and trapping for fur. Kit foxes are also hit by cars. Kit foxes are wary and nocturnal, with cryptic coloration, reducing their risk of predation.
Known Predators:
Anti-predator Adaptations: cryptic
Kit foxes are the smallest member of the family Canidae in North America. Their most distinctive feature is their exceptionally large ears placed close together on the head. The ears are from 71 to 95 mm in height and they play a role in dissipating heat and the excellent hearing of kit foxes.
Kit foxes range in color from yellowish to gray. They usually have a dark-colored back, light-colored undersides and inner ears, and distinct dark patches on each side of the nose and at the end of the tail. Males average slightly larger than females. Head and body length is from 485 to 520 mm in males (average 537) and from 455 to 535 mm in females (average 501). The tail is from 250 to 340 mm long. Males average 2.29 kg and females 1.9 kg, ranging from 1.6 to 2.7 kg.
Range mass: 1.6 to 2.7 kg.
Range length: 455 to 535 mm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: male larger
Vulpes macrotis survival rates are dependent on food availability, reproduction, and local predators. Different studies have estimated different life expectancies for kit foxes. Some report lifespans of 3 to 4 years, while others reported 7 to 12 years. In California a study of 144 kit fox pups showed a 74% mortality rate in pups within the first year.
Range lifespan
Status: wild: 7 (high) years.
Range lifespan
Status: captivity: 12 (high) years.
Average lifespan
Status: wild: 5.5 years.
Kit foxes are primarily found in arid regions, such as desert scrub, chaparral, and grasslands. Vegetation communities vary with the regional aridland fauna, but some examples of common habitats are saltbrush Atriplex polycarpa and sagebrush Artemisia tridentata. Kit foxes may also occur in agricultural areas and urban environments. They occur at elevations of 400 to 1900 meters. Kit foxes prefer areas with loose soils for constructing dens. They spend most of their time in dens that they dig themselves or take over from prairie dogs (Cynomys), other rodents, and American badgers (Taxidea taxus). Kit foxes occupy dens year-round and have several dens in their territory that they rotate among. Dens could have one or many entrances and are usually covered by thick brush. They usually stay in their dens during the daytime, exiting to hunt for food at night.
Range elevation: 400 to 1900 m.
Habitat Regions: temperate ; terrestrial
Terrestrial Biomes: desert or dune ; savanna or grassland ; chaparral
Other Habitat Features: urban ; agricultural
Kit foxes are primarily found in the southwestern part of the United States and northern and central Mexico. They are found as far north as the arid interior of Oregon, east to southwestern Colorado, south through Nevada, Utah, southeastern California, Arizona, New Mexico, and into western Texas. In Mexico they are found mainly in the states of Coahuila, Chihuahua, and Nuevo Leon, and throughout Baja California.
Biogeographic Regions: nearctic (Native )
Biologists sometimes gather information on the overall health of kit foxes Vulpes macrotis by gathering serum chemistry values.
Other common names include: desert fox, zorra del desierto, zorra norteña (Spanish), and wüstenfuchs (German).
Kit foxes have very large ears and excellent hearing. Kit foxes sometimes bark at perceived threats or use a "hacking growl" in intraspecific encounters.
Communication Channels: visual ; acoustic
Perception Channels: visual ; tactile ; acoustic ; chemical
Kit foxes are listed as "Least Concern" on the IUCN red list of threatened species. Populations throughout most of the United States are estimated to be stable. San Joaquin kit foxes, V. macrotis mutica, are considered endangered in the United States, as their habitat continues to be fragmented and lost to agriculture. Kit foxes are listed as species of concern in some states, including Colorado and Utah, where programs exist that are designed to protect kit fox populations. They are considered state threatened in California and state endangered in Oregon. In Mexico it is likely that kit fox populations are in decline as 40% of prairie dog populations have been converted to agriculture since 1994. Kit foxes are considered "vulnerable" in Mexico.
US Federal List: endangered
CITES: no special status
State of Michigan List: no special status
IUCN Red List of Threatened Species: least concern
Kit foxes can have a negative impact on humans by carrying diseases. The main disease of concern is plague, which foxes contract from fleas.
Negative Impacts: injures humans (carries human disease); causes or carries domestic animal disease
Kit foxes are important members of native ecosystems, helping to control rodent populations through predation.
Positive Impacts: research and education; controls pest population
Kit foxes are prey for other carnivores such as coyotes (Canis latrans) and bobcats (Lynx rufus). Also kit foxes are predators of rodents or other small animals, including black-tailed jackrabbits (Lepus californicus), kangaroo rats (Dipodomys), and prairie dogs (Cynomys). Because kit foxes move from den to den in search of a mate and food, their old dens are taken over by other kit foxes or other animals. As scavengers, kit foxes also play a major role in biodegradation.
Fleas, such as Pulex irritans and Pulex simulans, are common parasites of this species. Ticks are also common and include Ixodes texanus and Dermacentor perumapertus. Other cestode parasites include Mesocestoides corti, Mesogyna hypatica, and Dipylidium caninum. Unidentified roundworms and tapeworms have been noted from scat collections.
Ecosystem Impact: creates habitat; biodegradation
Commensal/Parasitic Species:
Kit foxes eat primarily rodents and rabbits. Species preyed on varies regionally, but the most common prey are prairie dogs (Cynomys species), kangaroo rats (Dipodomys species), black-tailed jackrabbits (Lepus californicus), and cottontail rabbits (Sylvilagus species). Kit foxes are primarily carnivores, but if food is scarce, they have been reported to eat tomatoes (Lycopersicon esculentum), cactus fruits (Carnegiea gigantea), and other available fruits. They also will scavenge carrion and eat large insects, lizards, snakes, and ground-dwelling birds.
Kit foxes may compete for food and dens with coyotes (Canis latrans), bobcats (Lynx rufus), red foxes (Vulpes vulpes), and American badgers (Taxidea taxus).
Animal Foods: birds; mammals; reptiles; carrion ; insects
Plant Foods: fruit
Primary Diet: carnivore (Eats terrestrial vertebrates)
Most studies have shown kit foxes to be monogamous, with pairs mating for life. Occasional polygyny has also been reported. When the female is ready to reproduce, she goes out on her own in search of a den. This usually happens around the month of September. In October, the male kit fox will join her and remain with her until the end of the breeding season. Female young will sometimes delay dispersal and stay an additional year beyond their independence to help raise their siblings.
Mating System: monogamous ; polygynous ; cooperative breeder
Kit foxes mate once per year from mid-December to February. The typical gestation period is 49 to 55 days, and they can produce a litter of 1 to 7 pups, with an average of 4. Births occus from February to mid-March. Although females are able to breed 10 months after birth, many females do not reproduce that first year. Young females are much lower reproductive success than do older females.
Breeding interval: Kit foxes breed once yearly.
Breeding season: Breeding occurs from December to February.
Range number of offspring: 1 to 7.
Range gestation period: 49 to 55 days.
Average weaning age: 8 weeks.
Range time to independence: 5 to 6 months.
Range age at sexual or reproductive maturity (female): 10 (low) months.
Range age at sexual or reproductive maturity (male): 10 (low) months.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization ; viviparous
Young stay in their birth den until they are 4 weeks old and are weaned at 8 weeks old. The young begin to hunt with their parents at 3 to 4 months old and are independent at 5 to 6 months old. Most young disperse by 8 months old. Both male and female parents care for and protect their young.
Parental Investment: altricial ; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Male, Female); pre-weaning/fledging (Provisioning: Male, Female, Protecting: Male, Female); pre-independence (Provisioning: Female, Protecting: Male, Female); post-independence association with parents; extended period of juvenile learning
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]
Some mammalogists classify it as conspecific with the swift fox, V. velox,[4] but 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.[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][2]
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]
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 mm 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]
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.[2] 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.[2] They are found at elevations of 400 to 1,900 meters (1,300 to 6,200 ft) above sea level.[12]
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.[2] Dens are spread across the home range, and an individual fox usually uses more than 11 dens in a given year.[2] 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]
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]
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]
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.
