Characteristics
Squirrels are generally small animals, ranging in size from the African pygmy squirrel at 7–10 cm (2.8–3.9 in) in length and just 10 g (0.35 oz) in weight, to the Alpine marmot which is 53–73 cm (21–29 in) long and weighs from 5 to 8 kg (11 to 18 lb). Squirrels typically have slender bodies with bushy tails and large eyes. Their fur is generally soft and silky, although much thicker in some species than others. The color of squirrels is highly variable between—and often even within—species.
The hind limbs are generally longer than the fore limbs, and they have four or five toes on each foot. Their paws on their fore feet include a thumb, although this is often poorly developed. The feet also have soft pads on the undersides.
Squirrels live in almost every habitat from tropical rainforest to semiarid desert, avoiding only the high polar regions and the driest of deserts. They are predominantly herbivorous, subsisting on seeds and nuts, but many will eat insects and even small vertebrates.
As their large eyes indicate, squirrels generally have an excellent sense of vision, which is especially important for tree-dwelling species. They also have very versatile and sturdy claws for grasping and climbing. Many also have a good sense of touch, with vibrissae on their heads and limbs.
The teeth of sciurids follow the typical rodent pattern, with large gnawing incisors that grow throughout life, and grinding cheek teeth set back behind a wide gap, or diastema. The typical dental formula for sciurids is
The life span of the Gray squirrel is approximately six years. Most urban squirrels do not reach their first birthday. This is due not to predators, but rather to automobiles. Compare this to its rural counterpart, which often perishes from lack of food.
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