SQUIRRELS AND RELATIVES FACTS
Squirrels are some of the most familiar rodents. They are small to medium-sized animals with relatively long tails. Squirrels have five toes on the back feet and four on the front feet, with a welldeveloped claw on each digit. Eyes are relatively high on the head and spread apart to allow them a wide range of vision. Size, fur, shape, and tail features depend upon the type of squirrel. There are three general body forms in these animals: flying squirrels, ground squirrels, and tree squirrels.
Flying squirrels have large, bushy tails and bodies adapted for moving between trees. They are generally slim with long legs. A furred membrane, double layer of thin skin, extends between the wrist and ankle, which allows them to glide. They have large eyes. Their fur is soft and dense and is generally brown, gray, or blackish in color. The underside is a paler color.
Ground squirrels range widely in size. The marmots are the largest ground squirrels, with weights of up to 16.5 pounds (7.5 kilograms); the smallest are the American chipmunks, which weigh up to 5 ounces (142 grams). These squirrels are typically short legged with muscular bodies. Their tails are furry, but generally not as bushy as those of tree squirrels.
Tree squirrels have long, bushy tails, sharp claws and large ears. Some have well-developed ear tufts. Tree squirrels also range extensively in size, from the pygmy squirrels that is about the size of a mouse, to the fox squirrels that can measure 18 to 27 inches (46 to 69 centimeters). Their hind legs are extremely long and they have long curved claws. Their tails are almost as long as their bodies.
Squirrels are found throughout the world, except in Australia, Madagascar, southern South America, and certain desert regions, such as in Egypt.
SQUIRRELS AND RELATIVES HABITAT
There are many types of flying squirrels found in south and southeast Asia, especially in tropical, hot and humid, forests. Some species live in northern temperate, not too hot or too cold, regions, up to the Arctic Circle.
Ground squirrels live in many different habitats, such as grassland, forests, meadows, and the arctic tundra. Chipmunks are the one type of ground squirrel that are often found in dense shrubs or closed forests.
Tree squirrels live in forests, woodlands, gardens, cities, and farmlands.
SQUIRRELS AND RELATIVES DIET
Most squirrels eat primarily plant materials. Tree squirrels and flying squirrels often eat nuts and seeds, and will occasionally also feed on fungi, eggs, insects, young birds, and small snakes. Ground squirrels also eat seeds, fruits, and nuts, but often have diets made up of large amounts of grasses and leafy materials.
BEHAVIOR AND REPRODUCTION
Most squirrels are active during the day, yet some species, such as all the flying squirrels, are nocturnal, active at night. Squirrels communicate by making shrill sounds. They also communicate by tail gestures, such as “flicking” the tail to indicate that another squirrel should go away. Most squirrels wrap their tail around themselves when resting. Squirrels build nests high in the trees called dreys, which are made of twigs and leaves. They line the inside of dreys with fur, feathers, or other soft material. The nest typically will have two exits. Squirrels also will build a nest called a den in the hollow of a tree.
Flying squirrels do not actually fly, as bats and birds do—they leap and glide. They leap from a high point, flattening their bodies and extending the legs widely, and then land at a lower point. Some species can glide for as much as 1,476 feet (450 meters). The squirrels can even turn at a right angle to avoid a branch.
Ground squirrels make burrows, tunnels or holes, which they use to rest in during the heat of the day and escape predators, animals hunting them for food. Many of the ground squirrels hibernate, become inactive to conserve energy, for varying periods of time. Some squirrels can hibernate for up to nine months.
Tree squirrels are solitary animals, yet some African species travel in pairs or small groups. These squirrels build nests of leaves or needles in hollow trees or limbs. They are active and maneuver (mah-NOO-ver) easily in trees.
For ground squirrels, the breeding season follows shortly after hibernation. Some species will skip a year of breeding; others can reproduce more than once a year. Baby ground squirrels are generally born underground without fur. There are usually four in a liter. Flying squirrels typically give birth to small litters of one to two offspring, which are generally blind and naked at birth. Tree squirrels generally have a polygamous (puh-LIH-guh-mus) mating system, meaning the male and female can have more than one mate. Litter sizes vary, depending upon the habitat and food availability.
SQUIRRELS AND PEOPLE
People have hunted squirrels for their fur and meat, and for sport. While squirrels are generally considered playful and harmless creatures, these animals can destroy crops and some people consider them pests. Their burrows occasionally damage irrigation systems and can harm livestock, but these rodents also destroy undesirable weeds and insects. Some squirrels are also carriers of organisms that transmit human disease, such as the plague and Rocky mountain tick fever. People have caused a decline in many squirrel populations by destroying their habitats and hunting them.
The World Conservation Union (IUCN) lists two squirrel species as Critically Endangered, facing an extremely high risk of extinction in the wild; nine species as Endangered, facing a very high risk of extinction; twenty-six species as Vulnerable, facing a high risk of extinction in the wild; and thirty-four species as Near Threatened, not currently threatened, but could become so.