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The fox squirrel (or eastern fox squirrel, Bryant's fox squirrel) (Sciurus niger) is the largest species of tree squirrel native to North America. Despite the differences in size and coloration, they are sometimes mistaken for American Red Squirrels or Eastern Gray Squirrels in areas where both species co-exist.
Eastern fox squirrels are most abundant in open forest stands with little understory vegetation; they are not found in stands with dense undergrowth. Ideal habitat is small stands of large trees interspersed with agricultural land. The size and spacing of pines and oaks are among the important features of eastern fox squirrel habitat. The actual species of pines and oaks themselves may not always be a major consideration in defining eastern fox squirrel habitat. Eastern fox squirrels are often observed foraging on the ground several hundred meters from the nearest woodlot. Eastern fox squirrels also commonly occupy forest edge habitat. Eastern fox squirrels have two types of shelters: leaf nests and tree dens. They may have two tree cavity homes or a tree cavity and a leaf nest. Tree dens are preferred over leaf nests during the winter and for raising young. When den trees are scarce, leaf nests are used year-round. Leaf nests are built during the summer months in forks of deciduous trees about 30 feet (9 m) above the ground. Eastern fox squirrels use natural cavities and crotches (forked branches of a tree) as tree dens. Den trees in Ohio had an average diameter at breast height (d.b.h.) of 21 inches (53 cm) and were an average of 58.6 yards (52.7 m) from the nearest woodland border. About 88% of den trees in eastern Texas had an average d.b.h. of 12 inches (30 cm) or more. Dens are usually 6 inches (15 cm) wide and 14 to 16 (35–41 cm) inches deep. Den openings are generally circular and about 2.9 to 3.7 inches (7.3–9.4 cm). Eastern fox squirrels may make their own den in a hollow tree by cutting through the interior; however, they generally use natural cavities or cavities created by northern flickers (Colaptes auratus) or red-headed woodpeckers (Melanerpes erythrocephalus). Crow nests have also been used by eastern fox squirrels. Eastern fox squirrels use leaf nests or tree cavities for shelter and litter rearing. 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. Overstory trees with an average d.b.h. of 15 inches (38 cm) or more generally provide adequate cover and reproductive habitat. Optimum tree canopy closure for eastern fox squirrels is from 20% to 60%. Optimum conditions understory closure occur when the shrub-crown closure is 30% or less.
Found climbing in an oak tree in front of my house