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 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.

[11] The gray fox displays white on the ears, throat, chest, belly, and hind legs.

[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.

[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 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.

Its strong, hooked claws allow it to scramble up trees to escape many predators, such as the domestic dog or the coyote,[30] or to reach tree-bound or arboreal food sources.

The gray fox is primarily nocturnal or crepuscular and makes its den in hollow trees, stumps or appropriated burrows during the day.

To avoid interspecific competition, the gray fox has developed certain behaviors and habits to increase their survival chances.

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.

[34] It also has been suggested that gray foxes could be more active at night than during the day to avoid their larger, diurnal competitors.

[35][36] 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.

In California, the gray fox primarily eats rodents (such as deer mice, woodrats, and cotton rats),[40] followed by lagomorphs, e.g. jackrabbit, brush rabbit, etc.

[40] 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.

[7] Generally, there is an increase in fruits and invertebrates (such as grasshoppers, beetles, butterflies, and moths)[40] within the gray fox's diet in the transition from winter to spring.

This marking serves the dual purpose of allowing them to find the food again later and preventing other animals from taking it.

[41] 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.

[44] 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).