Eastern Gray Squirrel (Sciurus carolinensis)

County List:

Rule:

Forested or Mixed Forested/Nonforested Landscapes

      (Oak (Lg Saw or Uneven))
      or (Assorted Hardwoods (Lg Saw or Uneven))
      or (Northern Hardwoods (Lg Saw or Uneven))
      or (Mixed Northern Hardwoods (Lg Saw or Uneven))
      or (Mixed Upland Hardwoods (Lg Saw or Uneven))
      or Residential
   containing:
      (Dead Down Woody Debris and Mast and Living Cavity Trees)

Habitat List:

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Literature:

Look for this squirrel wherever deciduous trees are abundant-in extensive forested tracts, dense woodlots, riparian strips, or even residential neighborhoods and city parks. It avoids young, second-growth woods in favor of large, mature trees that provide nesting hollows and edible nuts or seeds. Sizable stands of walnut, hickory, maple, or beech are preferable, although it also frequents mixed deciduous/coniferous stands.

An eastern gray squirrel seeks refuge in either a tree cavity or an exposed leafy nest. An ideal cavity is at least 12 inches deep and has an opening 3 inchs or more in diameter. A gray squirrel prefers a hollow high in a hardwood tree and often uses a cavity originally excavated by a woodpecker.

This species primarily feeds on acorns, walnuts, hickory nuts, and the like. In spring and summer, it supplements the diet with seeds, mushrooms, buds, flowers, fruits, and insects.

Habitat: Deciduous and mixed forests, especially those with trees that produce mast. River bottomland, woodlots in town, city parks.

Special Habitat Requirements: Oaks, tall trees for dens or leaf nests

Habitat Preferences: Throughout much of forested eastern United States, the fox squirrel often occupies the "upland" woods, the second growth and farm woodlots, while the gray squirrel is confined to the "big" timber along streams, especially where there is a broad river bottom habitat. One ideal habitat, according to Pack et al. is "over-mature" oak hickory woodlands, with an age of 150 to 200 years. Although second-growth timber is now maturing, much of it seems more capable of supporting fox squirrels than gray squirrels. Fortunately, groves of nut-bearing shade trees, established in city parks and along community streets now provide areas where gray squirrels can thrive.

The gray squirrel's attraction to mature groves of nut-bearing (and cavity-filled) oaks, hickories, and beeches has been cited by the numerous field observations of Michigan naturalists. The animals have been noted in forest stands of beech, beech-maple, hemlock-hardwoods, red and white pine, oaks, and mixed hardwoods. Although the second-growth forests are maturing, the mosaic patterns will prevail where suitable woodlands are scattered and frequently logged. However, as Beckwith suggested, the gray squirrel in Michigan is overshadowed by the fox squirrel in oak-hickory stands but comes to the fore when the beech-basswood-maple forest stage is reached.

Density and Local Movement: As a rule, gray squirrels live most of their lives in and around a single nest tree, perhaps moving no more than a few hundred yards in the course of any season.

Because of the reduction in quality of much gray squirrel habitat and the patchy condition of the currently favorable living places, there now seems little chance for observing the astounding numbers of these prolific squirrels as were recorded in Michigan a century or more ago.

Behavior: Gray squirrels use two types of arboreal refuges: dens in tree cavities, and leaf nests. Tree cavities are usually high in mature nut-bearing trees, as much as 40 feet above the ground. At lest two to three trees - with suitable cavities - per acre appear important for optimum gray squirrel habitat. The opening is at least 3 inches across and the cavity is more than 12 inches deep. This refuge can be either an enlarged woodpecker hole or an opening resulting from rot or a broken branch.

Nests of twigs and leaves are usually situated at least 20 to 30 feet above ground in mature oaks, hickories, maples, or elms. In more boreal woodlands, especially in northern areas, nests are frequently found in hemlock and white pine. Most of these nest sites are in forks where substantial branches grows out from the main tree trunk.

Food Habits: The gray squirrel has a varied but basically conservative taste for both plant and animal food. In summer there is usually a choice of animal materials and vegetative parts of plants; in winter the gray squirrel relies mostly on plant reproductive parts (seeds, nuts, acorns). In late winter and early spring, when stored acorns and other nuts are depleted, gray squirrels, and other arboreal sciurids, eat buds and later blooms of such trees as oaks, elms, maples, willow, and even the sap and inner bark of maple and elm. As the new growing season progresses, fungi, mushrooms, insects, insect galls, bird eggs, and fruits, such as grapes and thorn apples are eaten. In fact, about 76 different kinds of plants are consumed.

In autumn, maturation of acorns, walnuts, hickory nuts, and other tree fruits brings about a flurry of activity among the tree squirrels, as they not only feed on this crop but also store it for winter use. Gray squirrels generally hide these durable foods stocks in debris covering the forest floor, sometimes in openings in fallen logs and occasionally in tree cavities and in forks and trees. The nuts may be stored in quantities in cavities but usually singly in a hole in the ground.

Ecology: Eastern gray squirrels are most common in mature continuous woodlands >40 ha with a diverse woody understory. Densities are highest in habitats composed of tree species that produce winter-storable foods such as oak, hickory, and walnut. Due to the variability in seed production, a diversity of nut trees is important to support high densities.

Formation of den cavities requires 8-30 years. A minimum of 1 den/0.8 ha is required to maintain a density of 1 squirrel/1.6 ha. Addition of artificial nests increases densities. Selective cutting £55% of the basal area of trees ³30.5 cm dbh had little effect on densities, reproduction, or survival 1-2 year post-cut except for a temporary decrease in female survival. Female recovery rates were half those of males in a large clear-cut. Small (<8 ha), narrow (<160 m) clear cuts did not change any population parameters.