The family Sciuridae includes tree squirrels, ground squirrels, and flying squirrels. Tree squirrels have long, bushy tails, sharp claws and large ears. Some have well-developed ear tufts. Flying squirrels have a furred membrane (patagium) extending between the wrist and ankle that allows them to glide between trees. Ground squirrels are generally more robust than tree squirrels and often have short, sturdy forelimbs that are used for digging. Their tails, while fully furred, generally are not as bushy as those of tree squirrels.
Sciurids range in body size from mouse-sized African pygmy squirrels to robust red giant flying squirrels of Asia, weighing up to 3 kilograms. They vary greatly in geographic range and habitat. Squirrels are native throughout the world, with the exception of Antarctica, Australia, southern South America, and some desert regions. They occupy habitats ranging from tundra to rainforest. Some squirrels live solitary lives such as woodchucks, while others, such as prairie dogs, live in communities of hundreds of individuals with complex social structures. Squirrels are largely herbivorous, eating seeds, nuts, fruits, fungi, and other plant matter; however, insects, eggs and the occasional small vertebrate may be part of the diverse diet of these animals