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  The Mammals of Texas - Online Edition

Eastern Fox Squirrel
Order Rodentia : Family Sciuridae : Sciurus niger Linnaeus

Eastern Fox Squirrel (Sciurus niger).Description. A large tree squirrel with rusty or reddish underparts and brownish or grayish upperparts; tail usually less than half of total length, and cinnamon, mixed with black, in color; feet cinnamon. External measurements average: total length, 522 mm; tail, 245 mm; hind foot, 72 mm. Weight, 600-1,300 g.

Species distribution mapDistribution in Texas. Occurs in suitable habitats in eastern two-thirds of state. Introduced some places outside of native range.

Habits. Fox squirrels are adaptable to a wide variety of forest habitats, but in most areas open upland forests of mixed trees support the heaviest populations. The best habitat is mature oak-hickory woodland broken into small, irregularly shaped tracts of 2-8 ha and connected by strips of woodland which serve as squirrel highways. Intermixture of pine, elm, beech, pecan, maple, and other food-producing trees adds to the attractiveness of the habitat. Along the western parts of their range, fox squirrels are restricted more or less to river valleys which support pecans, walnuts, oaks, and other "required" trees.

Where hollow trees are available they are preferred as den sites and nurseries; if these are unavailable, the squirrels build outside "leaf" nests. These are composed of twigs and leaves, usually cut from the tree in which the nest is placed, and fashioned into roughly globular structures 30-50 cm in diameter surrounding an inner cavity 15-20 cm in diameter.

A fox squirrel occupies an area of at least 4 ha in extent in any one season, but during an entire year 16 or more ha may be utilized. Ranges of different fox squirrels overlap, and the animals are somewhat communal in their use of nests and probably also of winter food stores. A population of one squirrel to 1 ha is about the average carrying capacity of good, unimproved squirrel habitats.

Acorns are the natural mainstay of fox squirrels, although they are most important in fall and winter. Spring and summer foods consist of leftover mast, insects, green shoots, fruits, and seeds of such trees as elm and maple. Nuts are eaten from the time they start to develop and are buried in the fall in individual caches at the surface of the ground for winter use. The squirrels can relocate them by smell. Buds of many trees and fruits of osage orange add to the winter diet.

Mating occurs principally in two periods — January and February and again in May and June. The former period is most important. Old females usually breed twice a year and yearlings but once. The average female produces only four offspring each year. The gestation period is probably about 6 or 7 weeks, as in the gray squirrel. At birth the young are blind, nearly naked, and helpless. They develop rather slowly; their eyes open in the fifth week. They begin to climb about over the nest tree at the age of 7 or 8 weeks and to venture onto the ground at about 10 weeks. At the age of 3 months they begin to lead a more or less independent existence. Sexual maturity is reached at the age of 10-11 months.

Fox squirrels are important small game animals throughout most of their range, hence they are of decided economic value. Their fondness for green corn, however, often brings them into conflict with farming interests, as does their pilfering in nut orchards.