Gray foxes prefer to live in deciduous forests interspersed with brushy, woodland areas. Many populations thrive where woodlands and farmlands meet; however, red foxes (Vulpes vulpes) are known to frequent agricultural areas more than gray foxes. Proximity to water is a key feature of preferred habitat as well. Dens are usually located in hollow trees or logs, in crevices between and under large rocks, and in underground burrows. Dens have also been found in the lower forest canopy, 10 m above the forest floor, in hollow tree trunks and limbs. Gray foxes are the only member of the Canidae family that can climb trees. They are most often found below 3000 m in elevation.
Range elevation: 1000 to 3000 m.
Habitat Regions: temperate ; terrestrial
Terrestrial Biomes: savanna or grassland ; forest ; scrub forest
Gray foxes are found in the lower half of the Nearctic and northwestern part of the Neotropics. More specifically, their range spans from southern Canada to Venezuela and Columbia, excluding portions of the Great Plains and mountainous regions of northwestern United States and eastern coast of Central America.
Biogeographic Regions: nearctic (Native ); neotropical (Native )
Gray foxes are omnivorous. Although they prey on small vertebrates, fruit and invertebrates also form a substantial part of their diet. Cottontails (Sylvilagus floridanus), mice (Peromyscus), woodrats (Neotoma), and cotton rats (Sigmodon hispidus) form the majority of their winter diet. In the Sonoran Desert, the fruit of the California palm makes up a significant portion of their winter diet. With the onset of spring, fruits become an increasingly important part of their diet, at times making up 70% of its diet. Invertebrates, fruits, nuts, and grains also increase in importance during the spring. Grasshoppers (Orthoptera), beetles (Coleoptera), and butterflies and moths (Lepidoptera) are the preferred invertebrates. When available, gray foxes may also feed on carrion. When gray foxes accumulate an excess amount of food, they cache it by digging a hole with their forepaws and burying it. Immediately afterwards, they mark it with urine or using their scent glands on their paws and tail in an effort to ward off other animals as well as to make it easier to relocate.
Animal Foods: birds; mammals; eggs; carrion ; insects; terrestrial non-insect arthropods
Plant Foods: roots and tubers; seeds, grains, and nuts; fruit
Foraging Behavior: stores or caches food
Primary Diet: carnivore (Eats terrestrial vertebrates, Insectivore , Scavenger ); herbivore (Frugivore , Granivore ); omnivore
Gray foxes have a small, but important role in our ecosystems. Their feeding habits allow them to influence small rodent (Rodentia) populations by maintaining a steady predator-prey relationship. They serve as a host to many parasitic arthropods, including fleas (Siphonaptera), lice (Phthiraptera), ticks (Ixodida), chiggers (Trombidiformes), and mites (Acari). Gray foxes are also host to a number of internal parasites including nematodes (Nematoda), flukes (Trematoda), tapeworms (Cestoda), and acanthocephalans (acanthocephala)
Commensal/Parasitic Species:
Gray foxes are hunted and trapped for their pelt. Compared to red fox (Vulpes vulpes), gray fox pelts are less desirable because the hairs are coarser and shorter. Gray foxes may also help control the abundance of certain agricultural pests, including rodents (Rodentia) and rabbits (Leporidae).
Positive Impacts: body parts are source of valuable material; controls pest population
Gray foxes are considered a problem species by poultry farmers. However, red foxes (Vulpes vulpes) are commonly misidentified as gray foxes, and commonly attack and kill poultry as well. In addition, gray foxes carry zoonotic diseases that could be a potential health threat to humans (e.g., rabies) and domestic dogs (Canis lupus familiaris; e.g., tularemia and canine distemper).
Negative Impacts: injures humans (causes disease in humans , carries human disease); causes or carries domestic animal disease
Gray foxes are abundant throughout most areas in the lower two-thirds of North America. They have no special conservation status at this time. Although they are trapped and hunted by humans, there does not appear to be any immediate threat.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
IUCN Red List of Threatened Species: least concern
Like other members of the family Canidae, gray foxes are able to communicate by barking and growling. Males have been observed trying to attract potential mates by raising their hind leg to show off their genitalia. As juveniles, gray foxes commonly play fight. As adults, they use their scent glands to mark territories and food sources.
Communication Channels: tactile ; acoustic ; chemical
Other Communication Modes: pheromones ; scent marks
Perception Channels: visual ; tactile ; acoustic ; chemical
Lifespan for both captive and wild gray foxes ranges from 6 to 8 years. However, the oldest recorded wild gray fox was 10 years old at time of capture, and the oldest captive gray fox lived to be 12 years old.
Gray foxes generally live for 6 to 8 years. The oldest wild gray fox was 10 years old when captured. The oldest gray fox in captivity lived to be 12 years old.
Range lifespan
Status: wild: 6 to 10 years.
Range lifespan
Status: captivity: 6 to 12 years.
Typical lifespan
Status: wild: 6 to 8 years.
Typical lifespan
Status: captivity: 6 to 8 years.
Fully grown gray foxes display a mix of white, red, black and gray fur. However, new born pups tend to be dark brown. Gray foxes are medium-sized canids with elongated bodies and relatively short legs. They usually weigh between 3 and 5 kg, but can weigh up to 9 kg. Individuals at high elevation are slightly larger than their low elevation counterparts. Males are slightly larger than females, and skeletal measurements show that males have longer pelvises and calcanea, wider scapulae and more robust limb bones. In general, gray foxes can grow up to 1 m in length. Their tail makes up approximately one-third of their total body length and has a distinct black stripe along the dorsal surface and a black tip. The top of the head, back, sides, and rest of the tail are gray with the belly, chest, legs and sides of the face being reddish brown. The cheeks, muzzle and throat are white. Gray foxes have oval-shaped pupils and the area around the eyes has a thin black stripe from the outside corner of the eye to the side of the head. Additionally, a thick black stripe runs from the inside corner of the eye, down the muzzle to the mouth. They are sometimes misidentified as red foxes (Vulpes vulpes); however, red foxes have slit-shaped eyes, larger feet, longer legs, and a leaner body.
Range mass: 2 to 9 kg.
Range length: 800 to 1125 mm.
Average length: 1000 mm.
Other Physical Features: endothermic ; homoiothermic; bilateral symmetry
Sexual Dimorphism: male larger
Gray foxes primary predators include bobcats (Lynx rufus), golden eagles (Aquila chrysaetos), great-horned owls (Bubo virginianus) and coyotes (Canis latrans). In the southern region of the United States, gray fox abundance is highly dependent on coyote abundance. Other than death by natural causes, humans may be responsible for the greatest number of deaths and therefore may be their largest threat. Hunting, trapping and retaliatory killings by livestock ranchers are not uncommon. Unlike red foxes (Vulpes vulpes), which evade predators by using their superior agility, gray foxes escape by hiding under cover (e.g., brush piles). When escaping terrestrial predators, gray foxes can use their retractable claws to climb trees.
Known Predators:
Gray foxes are solitary animals that socialize only during mating season. They are typically monogamous, although in rare cases polygamy and polyandry occur. For a short period of time after parturition, family groups consisting of male, female, and young exist. Male-female pairings form in the fall with breeding occurring in the winter. During October and September, attracting mates become more competitive and males usually display more aggression while retaining and defending mates. Similar to domestic dogs (Canis lupus familiaris), gray foxes have scent glands just inside the anus. Additional scent glands are found on their face and the pads of their feet. Although these glands are primarily used to demarcate territory, they may also be used to attract potential mates.
Mating System: monogamous
Breeding season varies with geographic region, elevation, and habitat quality. Breeding occurs in yearly cycles, beginning in January through late February, continuing into March. In some areas (e.g., Texas), breeding has been observed as early as December. Parturition occurs after about 2 months of gestation, peaking in April, with an average litter size of 3.8 pups, which weigh about 86 g at birth. Pups are typically weaned by 3 to 4 weeks, but may not be completely weaned until 6 weeks. Both genders are sexually mature by 10 months old, soon after dispersal. Annual onset of spermatogenesis occurs earlier and last longer than estrus. If they have been exposed to significant levels of the synthetic estrogen, diethylstilbestrol, females may experience delayed fertilization.
Breeding interval: Gray foxes breed once yearly.
Breeding season: December through March.
Range number of offspring: 1 to 7.
Average number of offspring: 3.8.
Range gestation period: 53 to 63 days.
Average gestation period: 59 days.
Range weaning age: 2 to 6 weeks.
Range time to independence: 10 to 17 months.
Average time to independence: 12 months.
Average age at sexual or reproductive maturity (female): 10 months.
Average age at sexual or reproductive maturity (male): 10 months.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; viviparous
Average birth mass: 95 g.
Average number of offspring: 4.
Average age at sexual or reproductive maturity (male)
Sex: male: 365 days.
Average age at sexual or reproductive maturity (female)
Sex: female: 345 days.
Both genders take care of offspring in gray foxes. Before birth, males do a majority of the hunting, while females look for and prepare a suitable den. Weaning begins around 2 to 3 weeks of age. Pups begin eating solid food around 3 weeks old, which is primarily provided by the father. Parents teach pups how to hunt at around 4 months old. Until then, both parents prey for food separately, and pups practice their hunting skills by pouncing and stalking, which is primarily taught by the father. Pups depend on their parents for defense until about 10 months old, at which point they become sexually mature and disperse.
Parental Investment: precocial ; male parental care ; female parental care ; pre-hatching/birth (Provisioning: Male); pre-weaning/fledging (Provisioning: Male, Female, Protecting: Male, Female); pre-independence (Provisioning: Male, Female, Protecting: Male, Female)
The gray fox (Urocyon cinereoargenteus), or grey fox, is an omnivorous mammal of the family Canidae, widespread throughout North America and Central America. This species and its only congener, the diminutive island fox (Urocyon littoralis) of the California Channel Islands, are the only living members of the genus Urocyon, which is considered to be genetically basal to all other living canids. Its species name cinereoargenteus means "ashen silver".
It was once the most common fox in the eastern United States, and though still found there, human advancement and deforestation allowed the red fox to become the predominant fox-like canid. Despite this post-colonial competition, the gray fox has been able to thrive in urban and suburban environments, one of the best examples being southern Florida.[2][3] The Pacific States and Great Lakes region still have the gray fox as their prevalent fox.[4][5][6]
The genus Urocyon comes from the Latin 'uro' meaning tail, and 'cyon', meaning dog. The species epithet cinereoargenteus is a combination of 'cinereo' meaning ashen, and 'argenteus' (from argentum), meaning 'silver', referencing the color of the tail.
The gray fox is mainly distinguished from most other canids by its grizzled upper parts, black stripe down its tail and strong neck, ending in a black-tipped tail, while the skull can be easily distinguished from all other North American canids by its widely separated temporal ridges that form a ‘U’-shape. Like other canids, the fox's ears and muzzle are angular and pointed. Its claws tend to be lengthier and curved.
There is little sexual dimorphism, save for the females being slightly smaller than males. The gray fox ranges from 76 to 112.5 cm (29.9 to 44.3 in) in total length. The tail measures 27.5 to 44.3 cm (10.8 to 17.4 in) of that length and its hind feet measure 100 to 150 mm (3.9 to 5.9 in). The gray fox typically weighs 3.6 to 7 kg (7.9 to 15.4 lb), though exceptionally can weigh as much as 9 kg (20 lb).[7][8][9][10] The grey fox is readily distinguished from the red fox by its obvious lack of the "black stockings" that stand out on the red fox. The grey fox has a stripe of black hair that runs along the middle of its tail, and individual guard hairs that are banded with white, gray, and black.[11] The gray fox displays white on the ears, throat, chest, belly, and hind legs.[11] Gray foxes also have black around their eyes, on the lips, and on their noses.[12]
In contrast to all Vulpes and related (Arctic and fennec) foxes, the gray fox has oval (instead of slit-like) pupils.[13](p122) The gray fox also has reddish coloration on parts of its body, including the legs, sides, feet, chest, and back and sides of the head and neck.[10] The stripe on the fox's tail ends in a black tip as well.[14] Their weight can be similar to that of a red fox, but gray foxes appear smaller because their fur isn't as long and they have shorter limbs.[15]
The dental formula of the U. cinereoargenteus is 3.1.4.23.1.4.3 = 42.[11]
The gray fox appeared in North America during the mid-Pliocene (Hemphillian land animal age) epoch 3.6 million years ago (AEO) with the first fossil evidence found at the lower 111 Ranch site, Graham County, Arizona with contemporary mammals like the giant sloth, the elephant-like Cuvieronius, the large-headed llama, and the early small horses of Nannippus and Equus.[16] Faunal remains at two northern California cave sites confirm the presence of the gray fox during the late Pleistocene.[17] Genetic analysis has shown that the gray fox migrated into the northeastern United States post-Pleistocene in association with the Medieval Climate Anomaly warming trend.[18]
Genetic analyses of the fox-like canids confirmed that the gray fox is a distinct genus from the red foxes (Vulpes spp.). The genus Urocyon is considered to be the most basal of the living canids.[19] Genetically, the gray fox often clusters with two other ancient lineages: The east Asian raccoon dog (Nyctereutes procyonoides) and the African bat-eared fox (Otocyon megalotis).[20]
The chromosome number is 66 (diploid) with a fundamental number of 70. The autosomes include 31 pairs of sub-graded subacrocentrics, but one only pair of metacentrics.[21]
Recent mitochondrial genetic studies suggests divergence of North American eastern and western gray foxes in the Irvingtonian mid-Pleistocene into separate sister taxa.[22] The gray fox's dwarf relative, the island fox, is likely descended from mainland gray foxes.[23] These foxes apparently were transported by humans to the islands and from island to island, and are descended from a minimum of 3–4 matrilineal founders.[22]
The species occurs throughout most rocky, wooded, brushy regions of the southern half of North America from southern Canada (Manitoba through southeastern Quebec)[24] to the northern part of South America (Venezuela and Colombia), excluding the mountains of northwestern United States.[25] It is the only canid whose natural range spans both North and South America.[26] In some areas, high population densities exist near brush-covered bluffs.[11]
The gray fox is specifically adapted to climb trees. Its strong, hooked claws allow it to scramble up trees to escape many predators, such as the domestic dog or the coyote,[27] or to reach tree-bound or arboreal food sources. It can climb branchless, vertical trunks to heights of 18 meters and jump from branch to branch.[28] It descends primarily by jumping from branch to branch, or by descending slowly backwards like a domestic cat. The gray fox is primarily nocturnal or crepuscular and makes its den in hollow trees, stumps or appropriated burrows during the day. Such gray fox tree dens may be located 30 ft above the ground.[13](p122) For the most part, they rest on the ground rather than higher up in trees.
Prior to European colonization of North America, the red fox was found primarily in boreal forest and the gray fox in deciduous forest. With the increase in human populations in North America, their habitat selection has adapted: Gray foxes that live near human populations tend to choose areas near hardwood trees, locations used primarily by humans, or roads to utilize as their habitat.
The increase of coyote populations around North America has reduced certain fox populations, so gray foxes have to choose a habitat that will allow them to escape the coyote threat as much as possible, hence the choice of habitat nearer to areas where humans are active. The larger predators of the gray fox, like coyotes and bobcats, tend to avoid human-use areas and paved roads, making this habitat useful for the gray fox. They heavily utilize the edges of forests as a travel corridor, which is used for primary movement from place to place. Their choices do not change based on sex, the season, or the time of day. They also do the majority of their hunting in edges, and use them to escape from predators as well. Gray foxes are thus known as an “edge species”.[29]
Gray foxes often hunt for the same prey as bobcats and coyotes who occupy the same region. To avoid interspecific competition, the gray fox has developed certain behaviors and habits to increase their survival chances. In regions where gray foxes and coyotes hunt for the same food, the gray fox has been observed to give space to the coyote, staying within its own established range for hunting.[30][31] Gray foxes might also avoid their competitors by occupying different habitats than them. In California, gray foxes do this by living in chaparral where their competitors are fewer and the low shrubbery provides them a greater chance to escape from a dangerous encounter.[31] It also has been suggested that gray foxes could be more active at night than during the day to avoid their larger, diurnal competitors.[31]
Still, gray foxes frequently fall victim to bobcats and coyotes. When killed, the carcasses are often unconsumed, suggesting they are victims of intraguild predation.[30] These gray foxes are often killed on or near the boundary of their established range, when they begin to interfere with their competitors.[30] Gray foxes are known as mesopredators because they are mid-tier predators and their prey consists mostly of smaller mammals, while coyotes are known as de facto apex predators due to the removal of other apex predators like wolves in North America.[32][33] This explains the gray fox's tendency to change behavior in response to the coyote threat, as they are essentially lower on the food chain.
The gray fox is assumed to be monogamous, like other foxes. The breeding season of the gray fox varies geographically; in Michigan, the gray fox mates in early March, in Alabama, breeding peaks occur in February. The gestation period lasts approximately 53 days. Litter size ranges from 1–7, with a mean of 3.8 young per female.
The sexual maturity of females is around 10 months of age. Kits begin to hunt with their parents at the age of 3 months. By the time that they are 4 months old, the kits will have developed their permanent dentition and can now easily forage on their own. The family group remains together until the autumn, when the young males reach sexual maturity, then they disperse.[21] In a study of 9 juvenile gray foxes, only the males dispersed up to 84 km (52 mi). The juvenile females stayed within proximity of the den within 3 km (1.9 mi) and always returned.[34] On the other hand, adult gray foxes showed no signs of dispersion for either gender.[35] The gray fox will typically live between six and ten years.[36]
The annual reproductive cycle of males has been described through epididymal smears and become fertile earlier and remain fertile longer than the fertility of females.[21]
Logs, trees, rocks, burrows, or abandoned dwellings serve as suitable den sites. Dens are used at any time during the year but mostly during whelping season. Dens are built in brushy or wooded regions and are better concealed than the dens of the red fox.[11]
The gray fox is an omnivorous, solitary hunter. It frequently preys on the eastern cottontail (Sylvilagus floridanus) in the eastern U.S., though it will readily catch voles, shrews, and birds. In California, the gray fox primarily eats rodents (such as deer mice, woodrats, and cotton rats),[37] followed by lagomorphs, e.g. jackrabbit, brush rabbit, etc.[27] When available, gray foxes may also feed on carrion.[37] In some parts of the Western United States (such as in the Zion National Park in Utah), the gray fox is primarily insectivorous and herbivorous.[13](p124) Fruit is an important component of the diet of the gray fox and they seek whatever fruits are readily available, generally eating more vegetable matter than does the red fox (Vulpes vulpes).[7] Generally, there is an increase in fruits and invertebrates (such as grasshoppers, beetles, butterflies, and moths)[37] within the gray fox's diet in the transition from winter to spring. As nuts, grains, and fruits become more numerous, they are cached by foxes. Typically, they attempt to cover the area with their scent either through their scent glands or urine. This marking serves the dual purpose of allowing them to find the food again later and preventing other animals from taking it.[38]
Since woodrats, cotton rats, and mice make up a large part of the gray fox's diet, they serve as important regulators of small rodent populations.
In addition to their beneficial predation on rodents, gray foxes are also less welcome hosts to some external and internal parasites, which include fleas, lice, nematodes, and tapeworms.[38] In the United States, the most common parasite of the gray fox is a flea (Pulex simulans); however, several new parasitic arthropods were found in populations in central Mexico, and a warming climate may encourage them to migrate north.[39]
Gray foxes are hunted in the U.S. The intensity of the hunting has correlated with the value of their pelts. Between the 1970–1971 and 1975–1976 hunting seasons, the price of gray fox pelts greatly increased and the number of individuals hunted jumped over six-fold from 26,109 to 163,458.[21] It has been recently reported that over 500,000 gray foxes are killed every year for their fur.[40]
There are 16 subspecies recognized for the gray fox.[21]
Parasites of gray fox include trematode Metorchis conjunctus.[41] Other common parasites that were collected on gray foxes in Texas were a variety of tapeworms (Mesocestoides litteratus, Taenia pisiformis, Taenia serialis) and roundworms (Ancylostoma caninum, Ancylostoma braziliense, Haemonchus similis, Spirocerca lupi, Physaloptera rara, Eucoleus aerophilus). T. pisiformis was the most common parasite species and was associated with frequent impacts on health.[42]
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: CS1 maint: url-status (link) The gray fox (Urocyon cinereoargenteus), or grey fox, is an omnivorous mammal of the family Canidae, widespread throughout North America and Central America. This species and its only congener, the diminutive island fox (Urocyon littoralis) of the California Channel Islands, are the only living members of the genus Urocyon, which is considered to be genetically basal to all other living canids. Its species name cinereoargenteus means "ashen silver".
It was once the most common fox in the eastern United States, and though still found there, human advancement and deforestation allowed the red fox to become the predominant fox-like canid. Despite this post-colonial competition, the gray fox has been able to thrive in urban and suburban environments, one of the best examples being southern Florida. The Pacific States and Great Lakes region still have the gray fox as their prevalent fox.