Its strong, hooked claws allow it to scramble up trees to escape many predators, such as the domestic dog or the coyote, or to reach tree-bound or arboreal food sources. The gray fox is specifically adapted to climb trees. In some areas, high population densities exist near brush-covered bluffs. It is the only canid whose natural range spans both North and South America. 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. 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. The gray fox's dwarf relative, the island fox, is likely descended from mainland gray foxes. Recent mitochondrial genetic studies suggests divergence of North American eastern and western gray foxes in the Irvingtonian mid-Pleistocene into separate sister taxa.

The autosomes include 31 pairs of sub-graded subacrocentrics, but one only pair of metacentrics. The chromosome number is 66 (diploid) with a fundamental number of 70. 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 genus Urocyon is considered to be the most basal of the living canids. Genetic analyses of the fox-like canids confirmed that the gray fox is a distinct genus from the red foxes ( Vulpes spp.). 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. Faunal remains at two northern California cave sites confirm the presence of the gray fox during the late Pleistocene. 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. Gray fox kit at the Palo Alto Baylands in California Gray foxes also have black around their eyes, on the lips, and on their noses. The gray fox displays white on the ears, throat, chest, belly, and hind legs. 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 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 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 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 ranges from 76 to 112.5 cm (29.9 to 44.3 in) in total length. There is little sexual dimorphism, save for the females being slightly smaller than males. Its claws tend to be lengthier and curved. Like other canids, the fox's ears and muzzle are angular and pointed. 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.

Gray fur animal age