Squirrels are divided into three major species groups. They are tree squirrels, ground squirrels, and flying squirrels. Tree squirrels have long, bushy tails, sharp claws, and large ears. Ground squirrels more robust and smaller than Tree squirrels with sturdy fore-limbs to help with digging. Flying squirrels can glide up to 90 meters (250 feet) with the help of membrane of skin on either sides of the body.