More than 200 species of squirrels are found throughout the world; only Antarctica, Australia, Madagascar, New Zealand and southern South America have none. All squirrel species are one of three types: tree squirrels, ground squirrels and flying squirrels. They play an important part in controlling insect populations, distributing seeds, aerating soil and pollinating plants. Different species of squirrels range in length from 5 inches to 3 feet.
Tree squirrels consist of many species, including gray squirrels, black squirrels, red squirrels, fox squirrels and tufted-ear squirrels. They have long bushy tails and sharp claws. Tree squirrels are found in wooded areas, parks and residential areas. They build nests in hollow tree trunks or in the forks of branches. Tree squirrels hide food in small caches in the fall, scattering them over a large area. During winter they rely on these caches for meals.
Ground squirrels include chipmunks, prairie dogs, rock squirrels and marmots. They sleep, mate and nest in tunnels or burrows underground, spending their days foraging for food on the ground. Ground squirrels have short tails and sturdy forelegs designed for digging. They enjoy sunbathing on rocks and tree stumps. Ground squirrels are colonists, watching out for each other and giving verbal warnings when they sense danger. Some ground squirrels hibernate during the winter months.
The only nocturnal squirrels, flying squirrels don't really fly. They have parachute-like flaps of skin on their sides that connect to their front wrists and back heels. They are able to glide through the trees, up to 150 feet, by leaping to a distant tree branch with all four legs spread. Flying squirrels nest in tree holes. The northern flying squirrel and southern flying squirrel are the two species found in the United States.
Squirrels are omnivores, eating both plants and animals. Seeds, nuts, grains, fruits, berries, roots, leaves, flowers, pine cones, mushrooms, insects, bird eggs and newly hatched baby birds are all included in the squirrel's diet. Their varied menu depends on the region they live in and what's available there. The North American red squirrel, for instance, eats a specialized diet of conifer cone seeds.
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