Squirrels and Relatives: Sciuridae

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 well-developed 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.