Sciurus niger

Under a proposed taxonomic arrangement for Sciurini (de Abreu-Jr et al. 2020a, de Abreu-Jr et al. 2020b), S. niger (along with S. arizonensis, S. nayaritensis, S. alleni, and S. oculatus) would be moved to the genus Parasciurus; pending further investigation, this arrangement is tentatively not accepted following the American Society of Mammalogists (2024).

Large range in central and eastern U.S. and adjacent south-central Canada; introduced and established in many places in western North America; many occurrences and locally common, but typically rare in the southeastern U.S. where populations have declined and become fragmented due to loss of open mature forest habitat.

Most of the eastern and central United States and adjacent south-central Canada; New York to Florida, west along major river systems to New Mexico and Colorado (Geluso 2004), Wyoming, and Montana. Introduced and established in many areas in western North America and on Pelee Island, Ontario, Canada.

Weigl et al. (1989) recognized three morphologically and ecologically different but intergrading groups of fox squirrels (see also Williams 1977, Sherman et al. 1984). One group ("eastern fox squirrel") includes populations along the Coastal Plain from the Delmarva Peninsula to Central Florida and west to the eastern edge of the Mississippi River flood plain (Weigl et al. 1989), including subspecies niger, cinereus, bachmani, and shermani as mapped by Hall (1981). A second group ("western fox squirrel") ranges from the valleys of south-central Pennsylvania, the Appalachian mountains, and the uplands of the Gulf states west to the prairie (Weigl et al. 1989). A third "group" is an artificial one, including two isolated forms restricted to trophically poor, wetter areas in southern Florida (S. n. avicennia) and the Mississippi flood plain (S. n subauratus).

The greatest threat is to populations in the southeastern U.S., where distribution and abundance have been reduced by loss of mature forest habitat. The widely spaced trees typical of mature longleaf pine-turkey oak forest upon which populations in the southeastern U.S. depend favor the squirrel's large size, running proficiency, and tendency to escape along the ground. The very open, parklike forest stands resulting from frequent fires produce better crops of pine cones and mast (Goodrum 1938, Smith and Follmer 1972, Weigl et al. 1989). However, the longleaf pine ecosystem, which once comprised some 70 million hectares across the southeastern Coastal Plain, is today represented by only about 2% of its original range (Ware et al. 1993). Survival of the fox squirrel in the Southeast is intimately tied to the fortunes of this declining ecosystem. The squirrel's longleaf pine forest habitat is considered to be a fire climax (Waggoner 1975, Boyer and Peterson 1983, Christensen 1988, Platt et al. 1988). When fire is excluded, hardwoods become more abundant, the canopy begins to close, and the community begins to merge with adjacent deciduous forests and wetlands. These conditions favor the more abundant gray squirrel, which prefers densely stocked stands, dense undergrowth, and which tends to move through the canopy. While human modification of landscape has generally benefited fox squirrels in the western part of the range (Hibbard 1956, Weigl et al. 1989), fox squirrels in the southeastern U.S. have generally suffered. Their large body size requires substantial food supplies and large nesting cavities. These are found in open stands of mature, mast-producing trees. When these forests are logged, the second growth woodland that replaces these habitats, often with a dense understory, provides less of both key resources and also places a large cursorial species like the fox squirrel at higher risk of predation (Taylor 1973, Weigl et al. 1989). In addition, closed-canopy deciduous woodland with a well-developed understory favors the gray squirrel over most fox squirrels, and particularly over fox squirrels in the Southeast (Nixon and McCain 1969; Havera and Nixon 1978, 1980; Weigl et al. 1989). Home ranges of sympatric fox squirrels and gray squirrels may overlap without exclusion (Armitage and Harris 1982), but where the two species are in competition for the same but reduced food resources, lower energetic costs and higher reproductive potential favors the more numerous gray squirrel, particularly in years of poor mast production. Gray squirrels occur at higher densities, are able to exploit more numerous, smaller tree cavities and canopy food sources not available to fox squirrels, and are more likely to survive mast failures. Fox squirrels in the southeastern U.S. are highly adapted to and dependent on limited food supplies, so that anything that diminishes the quantity or quality of that habitat can have devastating effects. Because of their cursorial abilities and large size, which enable them to handle the massive cones of longleaf pine, they have an almost exclusive resource base as long as sufficiently extensive and mature tracts of this habitat exist. Habitat loss to development and agriculture is exacerbated by the conversion of pine-oak forests to large, heavily managed, short-rotation pine plantations, which provide little or none of the required food resources. Remaining longleaf and other pine forests are too small, too young, or too disturbed to provide adequate supplies of food (Weigl et al. 1989). Isolated patches of suitable habitat in the southeastern U.S. might still support fox squirrels that can move easily between them, but secondary succession in old fields and residential development has created migration corridors for gray squirrels, linking previously isolated fox squirrel habitat and enabling invasion by the more numerous gray squirrels (Weigl et al. 1989). Continued fragmentation of longleaf pine habitat also increases distances over which fox squirrels must travel in search of food, particularly in poor mast years. These factors put squirrels at greater risk of mortality from automobile traffic and predation by feral dogs. While leaf nests are built and used by fox squirrels in the southeastern U.S., cavity nests apparently are preferred for rearing young and as protection from severe weather conditions. Because the pine-oak forest typical of much of the squirrels' range is too young to have large numbers of suitable cavities, squirrels must rely on leaf nests, which may put their young at greater risk of predation, or they resort to cavities in adjacent bottomland forests where competition from other species may be high. Another threat to fox squirrel population in the southeastern U.S. may be their status as game animals. Weigl et al. (1989) suggested that, in large areas of good habitat, fox squirrel populations can probably support moderate hunting pressure, since low densities discourage hunters from specifically targeting fox squirrels. However, because of the squirrel's low reproductive rate, as the amount of suitable habitat continues to decline, hunting of smaller and more disjunct populations of squirrels could threaten regional survival of the species. Williams (1994) suggested that fox squirrel populations in longleaf pine sandhills in South Carolina may be adversely affected by hunting pressure. In these resource-poor habitats populations are "just hanging on." However, populations in bottomland hardwood areas may be able to better withstand hunting. Competitive and predation pressures on fox squirrels in the southeastern U.S. will increase as the acreage of preferred mature pine-oak forest is reduced and fox squirrels are forced into bottomland and successional forest, pine plantations, and developed areas. In addition, where large gray squirrel populations increase the prey base, sympatric fox squirrels may suffer higher predation, which an animal with low reproductive rates may not be able to support. Consequently, as the fox squirrel is forced into marginal habitats that favor other sciurids, they may be eliminated. See also files for subspecies.