In most areas, the animal's upper body is brown-grey to brown-yellow with a typically brownish-orange underside, while in eastern regions, such as the Appalachians, there are more strikingly-patterned dark brown and black squirrels with white bands on the face and tail.

In the South and parts of Nebraska and Iowa along the Missouri River,[7] there are populations with uniform black coats.

To help with climbing, the squirrels have sharp claws, developed extensors of digits and flexors of forearms, and abdominal musculature.

[8] "Fox squirrels also have several sets of vibrissae, hairs or whiskers that are used as touch receptors to sense the environment.

[9] The fox squirrel's natural range extends through most of the eastern United States, north into the southern prairie provinces of Canada, west to the Dakotas, Colorado, and Texas, and south to the northern parts of Coahuila, Nuevo León (as far south as the Valle de las Salinas) and Tamaulipas.

It is absent (except for vagrants) in New England, New Jersey, most of New York, northern and eastern Pennsylvania, Ontario, Quebec, and the Atlantic provinces of Canada.

It has been introduced to both northern and southern California,[10] Oregon,[11] Idaho,[12] Montana,[12] Washington,[12] and New Mexico,[12] as well as Ontario and British Columbia in Canada.

While very versatile in their habitat choices, fox squirrels are most often found in forest patches of 40 hectares or less with an open understory, or in urban neighborhoods with trees.

They thrive among oak, hickory, walnut, pecan and pine trees, storing their nuts for winter.

Western range extensions in Great Plains regions such as Kansas are associated with riverine corridors of cottonwood.

The actual species of pines and oaks themselves may not always be a major consideration in defining fox squirrel habitat.

[14] Forest stands dominated by mature to over-mature trees provide cavities and a sufficient number of sites for leaf nests to meet the cover requirements.

[19] This implies that this species cannot be imported, bred, transported, commercialized, or intentionally released into the environment in the whole of the European Union.

[21][22] Fox squirrels are not particularly gregarious or playful; in fact, they have been described as solitary and asocial creatures, coming together only in breeding season.

[23] They have a large vocabulary, consisting most notably of an assortment of clucking and chucking sounds, not unlike some "game" birds, and they warn of approaching threats with distress screams.

Pecans, black walnuts (Juglans nigra), osage orange (Maclura pomifera) fruits, and corn are also important fall foods.

[24] During the winter in Kansas, osage orange is a staple item supplemented with seeds of the Kentucky coffee tree (Gymnocladus dioicus) and honey locust (Gleditsia triacanthos), corn, wheat, eastern cottonwood (Populus deltoides var.

In the spring, fox squirrels feed primarily on buds of elm, maple, and oaks but also on newly sprouting leaves and insect larvae.

[24] Fox squirrels in Ohio prefer hickory nuts, acorns, corn, and black walnuts.

Fox squirrels also eat buckeyes, seeds and buds of maple and elm, hazelnuts (Corylus spp.

In California, fox squirrels feed on English walnuts (J. regia), oranges, avocados, strawberries, and tomatoes.

Autumn foods consist mainly of acorns, hickory nuts, beechnuts, walnuts, butternuts (Juglans cinerea), and hazelnuts.

If existing trees lack cavities, leaf nests known as dreys are built by cutting twigs with leaves and weaving them into warm, waterproof shelters.

Former predators extirpated from most of the fox squirrel's range include cougars (Puma concolor) and wolves (Canis lupus).

[6][16][24] Nestlings and young fox squirrels are particularly vulnerable to climbing predators such as raccoons (Procyon lotor), opossums (Didelphis virginiana), rat snakes (Pantherophis spp.