Species-Specific Management (SSM)

Gray Squirrel

The gray squirrel (Sciurus carolinensis) is an animal of hardwood and mixed pine-hardwood types. Productive gray squirrel habitat contains a variety of mast-bearing hardwood trees supplying needed foods for all seasons, and ample den cavities for escape cover, winter shelter, and brood rearing.

They den in hollows in trees when available, but they also utilize leaf nests, especially in spring and summer. These unusual assemblages high among tree limbs serve as refuge, resting and feeding stations and occasionally as nurseries. Placed in trees, they are constructed of twigs and leaves on the outside, and lined with shredded bark, plant fibers, and grasses.

Gray squirrels feed on a variety of foods, chiefly plant in origin. The chief food is mast of oak trees (the acorns), hickory nuts, walnuts, hickory, grapes, fungi, sedges, grasses, mulberry, larval and adult insects, and bird eggs and amphibians. They begin eating acorns in the Spring and continue throughout the year if they are available.

There are two breeding periods - early spring and late summer. After a gestation period of 40-45 days, the 2 to 4 naked, blind, and helpless young are born. They remain in the nest for about 6 weeks by which time their eyes are open and their teeth have developed so they can eat solid foods. By that time they weigh about 200 g. They remain in family groups for a month or so after they begin foraging for themselves. When 6 months old they are nearly adult in size and have left the home territory. They mature sexually in their first year and produce young of their own when about 12 months old.

These squirrels are highly prized as game, second only for many years to the cottontail rabbit as small game. In many parts of their range they are decreasing in numbers because of the removal of favored habitat by removal of land from forests and from logging operations. Short rotations favor small trees that are unsuitable for either feeding or denning of the squirrel. Consequently, sound management of their habitat is becoming an increasingly important responsibility. Their future will depend upon the acreage remaining in hardwood forests, the length of timber rotations, the species composition of hardwood stands, and the abundance of mast supplies and dens within old trees.

Because squirrels produce many young twice a year from early maturity, populations can naturally recover in 1-3 years if food and weather conditions are favorable. Hunting has little effect on population numbers. The natural mortality of gray squirrels is particularly high within the first year, and those young born in summer appear to have a higher mortality than those born in spring. Parasites such as fleas, botflies, and ticks are likely contributors to mortality.

Squirrels are the major food of bobcats, owls, hawks and snakes (when young) but this mortality probably does not limit the population.

Four major type-groups - Oak-Pine, Oak-Hickory, Oak-Gum-Cypress and White Pine-Yellow Poplar-Hemlock are well suited to management for gray squirrels under even-aged management, although certain forest types within these groups are not. Within them, consider the following:

1. Promote long rotation ages and have at least 1/20 of the forested area in mature timber (older than 50) at all times. (This can be in very steep or inaccessible areas or "lands-unsuitable for logging")
2. Retain hardwood or mixed pine/hardwood types.
3. Assure rotation of harvest to assure adjoining nesting areas with food areas, every year.
4. In pine types, create or retain hardwood patches (5 acres or more)
5. Plant mast producing trees along fences, streams, etc.
6. Erect nest boxes where cavity trees are lacking.
7. Protect den trees. Den trees are essential to squirrels for winter shelter, escape cover, and rearing of young. Natural den cavities begin to appear in 40-50 year old stands. (Although leaf nests are also used, the survival rate of young is 40% lower in leaf nests compared to cavities.) Frequently, squirrels will claim 2 or 3 dens at the same time. Managers should work for 2 to 3 suitable cavities per acre. Moderate to dense ground cover near den trees seems desirable as cover and concealment as well as for summer soft- mast foods.
8. Population densities are limited in the wild. (Unusually high populations occur in cities where food and nest-sites are abundant and (most importantly) constant.)The home range of gray squirrels varies from 1.5 to 8 acres and is usually smaller where populations are high.
9. Protect mast-producing groves of trees.
10. Thin mast producers to produce large crowns and to increase nut production in well-distributed stands.
11. Work with state agencies to achieve an optimum hunting bag limits and season (Giles and Lee 1979), one that meets many complex objectives.
12. Keep records of harvests and hunter and observer times spent in using the resource. Report changes as a function of funds spent or profits foregone.
13. Predict squirrel hunting pressure and decide on current practices responsive to such likely changes.
14. Discourage discarding carcass when bot fly larvae (Cuterebra warbles or "wolves") are found (380,000 estimated disposed each year in North Carolina in 1960s)

Interest: very small tooth at front molar on the upper teeth.

Submitted by Robert H. Giles, Jr.

This Web site is maintained by R. H. Giles, Jr.
Last revision July 17, 2002.