When we think of squirrels, we generally think of trees and hard mast. Nevertheless, squirrels use a variety of habitats, including clearcuts. Also, young stands become old stands, which will then support higher densities of squirrels.
Generally, gray squirrels favor hardwood and mixed pine-hardwood types. However, their abundance in urban areas is proof that they also thrive in openings and along edges. A common denominator in these seemingly dissimilar habitats is a variety of mast-producing hardwood trees (USDA 1971).
Huntley (1986) states that throughout the eastern United States, gray squirrels are most abundant in unfragmented bottomland and mesic upland forests with closed canopies. In Louisiana, no gray squirrels were captured in stands that had been thinned or selectively cut, regardless of their state of regeneration (McElfresh et al. 1980). A study in southeastern Ohio by Nixon et al. (1980) found that most gray squirrels using clearcuts (22 years old) in hardwood stands were likely to be transients. They also found that squirrels foraged farther into 15- and 20-year-old stands than in stands only 7 years old.
Several other studies in Texas, Mississippi, and Alabama found that squirrel populations remained high following cutting in pine, hardwood, or mixed pine-hardwood forests if streamside management zones (SMZs), hardwood stringers, or other strips of natural vegetation are retained (Hedrick 1973, McElfresh et al. 1980, Warren and Hurst 1980, Dickson and Huntley 1985, Dickson 1989, Fischer and Holler 1991). Dickson (1989) found that virtually no squirrels or squirrel nests were in SMZs less than 130 feet wide, but they were common in SMZs more than 165 feet wide.
Most published studies of fox squirrels indicate that this species is primarily associated with older age classes of forests. Fox squirrels occupy both hardwood and pine habitat, but are more tolerant of open conditions than gray squirrels. Nevertheless, both species overlap somewhat in their use of habitats (USDA 1971, Flyger and Gates 1982). In pine habitat, fox squirrels occur mostly in xeric upland habitats with sparse woody understories (Huntley 1986) while gray squirrels prefer the denser vegetation of flood plain and bottomland habitats. Fox squirrels in North Carolina preferred open, mature, pine-oak habitat, especially longleaf pine-turkey oak and the ecotones between pine and other vegetation types (Weigel et al. 1989). In the South Carolina Coastal Plain, fox squirrels used ecotones and brush with a young hardwood overstory more often than predicted by availability, while avoiding mowed fields and young pine plantations (Whitehouse 1989). Female fox squirrels often selected older growth habitats than males, including old pine-sawtimber and mixed pine-hardwoods.
Southern flying squirrels reach their greatest abundance in hardwood forests (Cronan and Brooks 1962) because of the hard mast and tree cavities found there. They also are found in large enough numbers in pine stands to be a major cavity competitor for red-cockaded woodpeckers (Harlow and Lennartz 1983).
Young stands lacking hard mast or snags generally are not preferred habitats for southern flying squirrels. In central Massachusetts, southern flying squirrel numbers decreased in response to small plot clearcuttings (Dykema 1990). Studies of the southern flying squirrel in New Hampshire indicate home range size is regulated to some extent by the abundance of hard mast resources. Core areas contained significantly more snags, large hickories, beeches, and total large-mast producing trees than did low-use areas (Fridell 1990). Even in mature, even-aged pine stands in the Coastal Plain of South Carolina, acorns are an important food year-round (Harlow and Doyle 1990). Regenerating stands created through clearcutting will, over time, regain habitat attributes favored by southern flying squirrels. In a study by Healy and Brooks (1988) in West Virginia, southern flying squirrel capture rates were not correlated with stand age or overstory structure in 12 even-aged stands ranging from 8 to 205 years old.Next page...Effects of Clearcutting on Nongame Small Mammals