Squirrels belong to the family Sciuridae, which is made up of small- to medium-sized rodents. Other members of the family include chipmunks, marmots and prairie dogs. Squirrels range in length from 5 inches up to 3 feet. They are native to Canada, North America, South America, Asia, Africa and Europe, and have been introduced into Australia. This broad geographic range helps to explain why there are over 200 species of squirrel in the world. Three groups of squirrels found in the United States are tree squirrels, ground squirrels and flying squirrels.
Fox squirrels (Sciurus niger) are tree squirrels that inhabit the eastern half of the United States. They are so named because of the reddish gray and pale brown color of their fur, resembling the appearance of fox fur. Although tree squirrels depend on trees for food and protection from predators, fox squirrels spend an appreciable amount of time on the ground. They spend more time foraging on the ground compared to neighboring species of tree squirrel like the eastern gray squirrel. Fox squirrels will even spend time in fields far away from any trees. These squirrels prefer environments where woodland and open fields border each other.
Eastern Gray Squirrel
The eastern gray squirrel (Sciurus carolinensis) inhabits the western-most states and the eastern half of the United States. They are a very adaptable species, which explains their broad geographic range. Their adaptability has allowed them to inhabit and thrive in city parks and other human developments. Since they are tree squirrels, they spend a majority of their time in trees where they eat, sleep and rest. They often live in areas with other tree squirrel species like the fox squirrel. One way to tell the eastern gray squirrel apart from other species of tree squirrel is by the gray fur on the top of its body and its white underside. They weigh up to 1.5 pounds, measure between 18 and 20 inches in length, and have a broad and bushy tail.
California Ground Squirrel
The California ground squirrel (Spermophilus beecheyi) inhabits California, Oregon and Washington. They forage above ground near their burrows, eating a diet of nuts, fruits, roots and small animals. It is common to find this squirrel residing in a home garden. This squirrel is sometimes considered a pest because of the damage it inflicts on garden produce. If a ground squirrel is seen in the garden, it can be identified as a California ground squirrel by its brown fur and semi-bushy tail. There is little chance of seeing this squirrel during the winter gardening season, however, because that is its hibernation period.
Southern and Northern Flying Squirrel
The southern flying squirrel (Glaucomys volans) and the northern flying squirrel (Glaucomys sabrinus) are two species found in the U.S. Two distinct physical traits of flying squirrels are their flat tails and the flap of skin that connects their fore and hind legs. These features allow flying squirrels to glide in the air for distances up to 150 feet. They glide from tree to tree looking to consume nuts, fruits and small birds. The northern flying squirrel can be found in the northernmost states across the U.S., while the southern flying squirrel is found in the eastern half of the country.