Gray Fox

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in biology, Gray Fox (Alias:Grey Fox Latin:Urocyon Cinereoargenteus)  is an omnivorous mammal of the family Canidae, widespread throughout North America and Central America. The body color is grey, with a clear light red line in the gray areas on the neck, sides and limbs, and white on the belly, chest and cheeks. The tail is long and fluffy, with a dark stripe on the back of the tail and a dark tip. Life span is 4-5 years in the wild and 14 years in captivity.

Gray Fox is found in the southeastern tip of Canada, most of the United States, Central America, the northernmost tip of Colombia, and northern Venezuela. Inhabits temperate and tropical forests, woodlands, shrubs, semi-dry shrubs, agricultural habitats and suburban areas of towns. It has outstanding climbing ability. It forages on the ground and can also climb up to 18 meters high to forage in trees. It mainly forages alone at night. Omnivorous, preying on rodents and hares in winter, almost exclusively insectivorous in summer, and feeding on fruits, seeds, and nuts in autumn, as well as small reptiles, birds, eggs, and carrion. Monogamy. Seasonal breeding, mating from January to April, giving birth from March to early June, the gestation period is 60-63 days, and the maximum number of litters per litter is 10, usually 3-5.

Gray Fox is widely distributed and is a common animal. Legal hunting is the main cause of mortality, and although hunting itself does not pose a threat, it may have an impact on the population if there is a concurrent disease outbreak.

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). 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. The gray fox displays white on the ears, throat, chest, belly, and hind legs. Gray foxes also have black around their eyes, on the lips, and on their noses.

In contrast to all Vulpes and related (Arctic and fennec) foxes, the gray fox has oval (instead of slit-like) pupils.(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. The stripe on the fox's tail ends in a black tip as well. Their weight can be similar to that of a red fox, but gray foxes appear smaller because their fur is not as long and they have shorter limbs.

The species occurs throughout most rocky, wooded, brushy regions of the southern half of North America from southern Canada (Manitoba through southeastern Quebec) to the northern part of South America (Venezuela and Colombia), excluding the mountains of northwestern United States. It is the only canid whose natural range spans both North and South America. In some areas, high population densities exist near brush-covered bluffs.

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. Faunal remains at two northern California cave sites confirm the presence of the gray fox during the late Pleistocene. 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.

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. 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).

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.

Recent mitochondrial genetic studies suggests divergence of North American eastern and western gray foxes in the Irvingtonian mid-Pleistocene into separate sister taxa. The gray fox's dwarf relative, the island fox, is likely descended from mainland gray foxes. 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.

Gray Fox is monogamous. The breeding season of Gray Fox varies by region. In Michigan, the breeding season is in early March. In Alabama, the breeding peak occurs in February. The gestation period lasts approximately 53 days. There are 1-7 litters per litter, with an average of 4 litters. The newborn cub weighs 100 grams. The cub opens its eyes after 10 days and is weaned after 12 weeks. During this period, the father provides food to the entire family. It takes 3 months for the fox cubs to grow the same fur as their parents. At 4 months of age, permanent teeth grow and the pup can hunt its own prey. At this time, it can easily hunt its own prey. The family lived together until the fall, but began to separate in the winter, and Gray Fox usually lived on his own during the winter. The young Gray Fox will reach sexual maturity after one year. When the young Gray Fox reaches sexual maturity, it will leave the family to fend for itself. 

This species has a wide distribution range and is not close to the fragile and endangered critical value standard for species survival (distribution area or fluctuation range is less than 20,000 square kilometers, habitat quality, population size, distribution area fragmentation), and the population number trend is stable, so it is evaluated as None A species in existential crisis.

Not included in CITES appendix. Gray Fox is legally protected in Canada and the United States. The Gray Fox lives in many protected areas throughout its range, such as Big Bend National Park, San Joaquin National Wildlife Refuge, Rocky Mountain National Park, Everglades and Turtle National Park, and Adirondack National Park. . There are also some Gray Foxes kept in captivity. Gray Foxes do well in captivity and are usually exhibited in zoos and wildlife farms.