SQUIRREL,
common name for many rodents of the family Sciuridae, which
also includes the woodchuck, CHIPMUNK, and PRAIRIE DOG, (qq.v.);
the genus Sciurus includes many common American
species. The subfamily Sciurinae includes the tree and ground squirrels,
with about 225 species; and the subfamily Petauristinae includes
the so-called flying squirrels, with about 35 species. Squirrels
range in size from the pygmy squirrels of Africa, genus Myosciurus, which
are about 13 cm (5 in) long, to the giant squirrels of Asia, genus Ratufa, which
are about 90 cm (36 in) long. The animals are in all parts of the
world except Australia.
Except for the ground squirrels, the animals live mainly in
trees, and their food is largely vegetable (especially nuts, seeds,
and buds), although they occasionally eat insects. Their habit of
storing seeds helps in the dispersion of trees and other plant forms.
In colder climates, ground squirrels commonly hibernate; tree squirrels
do not.
In North America, one of the most common and widely distributed
species is the red squirrel, Tamiasciurus hudsonicus, which
ranges from northern and mountainous parts of the U.S. to the limit
of trees in Canada. East of the Great Plains occur the eastern fox
squirrel, S. niger, and the eastern gray squirrel, S. carolinensis. The
latter is a familiar dweller in city parks and, since its introduction
into Great Britain, has replaced the native red squirrel, S.
vulgaris, in many areas. A similar form in the western
U.S. is the California gray squirrel, S. griseus. In
the Great Plains region are found the ground squirrels, of which
the 13-striped Spermophilus tridecemlineatus is
a common variety.
Flying squirrels have a folded layewr of loose skin along each
side of the body, from the front to the hind leg. When outstretched,
this skin supports the animals as they glide from tree to tree.
In Africa, another rodent family, the Anomaluridae, contains squirrellike
gliders called scaly-tailed flying squirrels.