squirrel corn: see fumitory.

squirrel, name for small or medium-sized rodents of the family Sciuridae, found throughout the world except in Australia, Madagascar, and the polar regions; it is applied especially to the tree-living species. Tree squirrels range from the size of a mouse to the size of a house cat and vary greatly in color; some Asian tree squirrels are brilliantly patterned. In addition to the tree squirrels, the family includes the ground squirrel, chipmunk, marmot, woodchuck, prairie dog, and flying squirrel.

Tree Squirrel Characteristics and Behavior

The so-called typical tree squirrels are members of the genus Sciurus, with about 40 species distributed throughout forested regions of Eurasia and the Americas. These are day-active animals with slender bodies, sleek, thick fur, and bushy tails. Their coats are black, gray, brown, or reddish above and light-colored below. Light, swift, and agile, tree squirrels leap from branch to branch and scurry up and down trees using their sharp claws to dig into the trunk; they always descend head first. The tail is used as a rudder when the animal leaps and as a parachute when it drops. They have excellent sight, including good color vision. The handlike forepaws are used for holding food. Tree squirrels make nests in holes in trees or on branches. They spend much time on the ground, foraging for fruit, nuts, and insects; they also sometimes eat eggs, young birds, and smaller mammals. Members of many species store food for the winter in holes or buried in the ground; they locate these stores by means of smell. They do not hibernate.

Types of Tree Squirrels

Sciurus species include the Eurasian red squirrel, S. vulgaris, and the North American gray squirrels, fox squirrel, and tufted-eared squirrels. Gray squirrels have tails about as long as the combined head and body length. The eastern gray squirrel, S. carolinensis, common in the eastern half of the United States and extreme southern Canada, is up to 20 in. (51 cm) in total length, 5 in. (13 cm) high at the shoulder, and weighs 1 to 11/2 lb (450-700 grams). It has been introduced in Europe. The western gray squirrel, S. griseus, of the U.S. West Coast, is slightly larger. The fox squirrel, S. niger, is the largest North American squirrel, reaching 29 in. (74 cm) in total length; its head is somewhat square. It displays great variation in its fur color but is commonly light brown. It is found in the eastern half of the United States, excluding the extreme northeast. Although its numbers have been greatly diminished by hunting and clearing, it is still common in some areas. It has also been introduced in city parks in western states. The tufted-eared squirrels, also called tassel-eared, or Abert, squirrels, are very distinctive, with tall plumes of hair on their ears. They inhabit yellow pine forests of the Colorado Plateau. One variety, the Kaibab squirrel, is found only on the northern rim of the Grand Canyon. North American red squirrels, also known as pine squirrels and chickarees, are species of the genus Tamiasciurus. They are small and noisy, about 12 in. (30 cm) long and 31/2 in. (9 cm) high, weighing 5 to 10 oz (140-280 grams). They are found in the pine forests of Alaska, Canada, and the N and W United States. Other genera of arboreal squirrels are found mostly in Africa, S and SE Asia, and Central and South America.

Classification

Squirrels are classified in the phylum Chordata, subphylum Vertebrata, class Mammalia, order Rodentia, family Sciuridae.

ground squirrel, name applied to certain terrestrial rodents of the squirrel family. In North America the name refers to members of the genus Citellus and sometimes to the closely related genera Tamias (chipmunk), Cynomys (prairie dog), and Marmota (marmot and woodchuck). Citellus species are found in Asia, E Europe, and North America. In the Old World they are called sousliks. Other ground squirrel genera are found in Africa and S Asia. The approximately 30 North American species of Citellus are found W of Hudson Bay, from the Arctic Ocean to central Mexico. These ground squirrels have rounded heads, short ears and legs, and shorter, less bushy tails than tree squirrels. Their combined head and body length is 41/2 to 131/2 in. (11.4-33 cm) depending on the species; the tail is usually a third to two thirds as long. Most are gregarious, living in extensive underground burrows; they hibernate in colder parts of their range. Members of different species are found in prairie grasslands, arctic tundra, mountain meadows, open forest, desert, and scrub country. In some regions the ground squirrel is called gopher, a name more commonly applied to burrowing rodents of a different family. Primarily vegetarian in their diet, ground squirrels may become agricultural pests, but they destroy insects and mice as well as crops. Their tunnels cause landslides and erosion, but also serve to mix and aerate the soil. Ground squirrels are classified in the phylum Chordata, subphylum Vertebrata, class Mammalia, order Rodentia, family Sciuridae.

flying squirrel, name for certain nocturnal tree squirrels adapted for gliding; they do not actually fly. Most are found in Asia, but one species of the genus Pteromys extends into SE Europe and the two species of Glaucomys are found in North America. The gliding mechanism is a fold of furry skin extending along each side of the body from the wrist to the ankle and, in some species, to the tail. When the animal is at rest the flaps are folded; when it stretches its limbs for leaping, as do all tree squirrels, the flaps are stretched out taut like a parachute. The tail in many species is broad and flat, with a flat row of hairs on either side. The animal uses movements of the flaps, limbs, and tail to control direction. The glide always starts from a high tree branch; if it is a long glide the animal comes to rest near the ground and must climb up again. The small North American flying squirrels leap from heights of 50 ft (15 m) or more and may travel a horizontal distance of over 100 ft (30 m). Flying squirrels are seldom seen because of their nocturnal habits and high dwelling places. They nest, often many together, in holes in trees. They feed on a variety of plant matter, as well as on insects. The North American flying squirrels, found in forested regions over much of the continent, have soft, thick, brownish fur. The northern species, Glaucomys sabrinus, of Canada and the NE and W United States, is up to 12 in. (30 cm) long including the tail, which is nearly as long as the head and body; it weighs 4 to 61/2 oz (110-180 grams). The southern species, G. volans, of the eastern half of the United States and parts of Mexico and Guatemala, is slightly shorter and weighs about a third as much. Most Old World species are similar, but the giant flying squirrels, genus Pteromys, of S Asia, are up to 4 ft (120 cm) long and may be observed sleeping on branches during the day. The scaly-tailed squirrels, or African flying squirrels, are not true squirrels, but members of a separate rodent family (Anomaluridae). Found only in tropical Africa, they are anatomically quite different from the true flying squirrels and include both gliding and nongliding species. Flying squirrels are classified in the phylum Chordata, subphylum Vertebrata, class Mammalia, order Rodentia, family Sciuridae.

Any of several species (genus Saimiri, family Cebidae) of arboreal New World monkeys, found in groups of up to several hundred during the day in riverside forests of Central and South America. They eat fruit, insects, and small animals. They are 10–16 in. (25–40 cm) long and have a heavy, nonprehensile, black-tipped tail, 15–19 in. (37–47 cm) long. They have a small white face, large eyes, and large, usually tufted, ears. The short, soft coat is grayish to greenish, with yellow or orange arms, hands, and feet. The crown of the common squirrel monkey (S. sciureus) is olive or grayish; the red-backed squirrel monkey (S. oerstedii) has a black crown and reddish back.

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Any of about 260 species in 50 genera (family Sciuridae) of mostly diurnal rodents found almost worldwide. Many species are arboreal; some are terrestrial. All species have strong hind legs and a hairy tail. They vary widely in colour and form and range in total length from the 4-in. (10-cm) African pygmy squirrel to the giant squirrels of Asia, about 35 in. (90 cm) long. Tree dwellers live in a tree hollow or nest, and most are active year-round. Ground dwellers live in burrows, and many become dormant in winter (hibernate) or summer (estivate). Most species are primarily vegetarian and are fond of seeds and nuts; some eat insects or supplement their diet with animal protein. Seealso chipmunk; flying squirrel; ground squirrel; marmot; prairie dog.

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Any of numerous relatively short-legged, terrestrial rodents of the squirrel family (Sciuridae), found in North America, Mexico, Africa, Europe, and Asia. The name is often applied to chipmunks. Ground squirrels belong to the genera Ammospermophilus, Xerus, Atlantoxerus, and Spermophilus. They live in burrows, sometimes in colonies. Though primarily herbivores, some feed on insects and other small animals and on carrion. Many species collect food, carrying it in their cheek pouches, and store it in their burrows. Those in cold areas may hibernate in winter; those in dry areas may become dormant in summer. Species range from about 7 to 20 in. (17–52 cm) in length, including the tail.

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Any member of two distinct groups of rodents that are able to make gliding leaps by means of parachute-like membranes connecting their forelegs and hind legs on each side. North American and Eurasian flying squirrels, in the squirrel family (Sciuridae), are slender, long-limbed forest dwellers with soft fur and large eyes. They are 3–24 in. (8–60 cm) long, excluding the often-flattened tail, and feed on nuts, fruit, other plant material, and insects. They seldom descend to the ground. They can glide 200 ft (about 60 m) or more from one tree to another. The scaly-tailed flying squirrels of Africa (family Anomaluridae) have rows of scales on the underside of their tufted tail that help them climb and cling to trees. They are similar in appearance and feeding preferences to the sciurids and are about 4–16 in. (10–40 cm) long without the tail.

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