Unlike other squirrels, flying squirrels are nocturnal. Fox, gray, red, and flying squirrels nest and spend most of their time in trees. The Red giant flying squirrel is a large species of flying squirrel. Northern flying squirrels (Glaucomys sabrinus) and southern flying squirrels (Glaucomys volans) are the only two native flying squirrel species found in North America.They are both gray-brown, but the northern flying squirrel has belly fur that is gray at the base, and for the southern flying squirrel the belly fur is all white. Description. Chipmunks, woodchucks and ground squirrels have dens underground and rarely spend time in trees. Eastern fox squirrel; Eastern gray squirrel; Red Squirrel; Flying Squirrels: Two species of flying squirrels … These flying squirrels have dark red colouring, large eyes and long slender tail. They have a membrane of skin between their legs and arms, which is used to glide between trees. Nests are made of leaves, shredded bark, mosses, or lichens. Red squirrels are sometimes called “pine squirrels” or “chickarees”; the gray squirrel is also known as the “eastern gray squirrel.” Both are members of the squirrel family, along with flying squirrels, chipmunks, and woodchucks. Some also build globular nests high in trees where branches join the trunk. They den in tree cavities, grottoes or rock crevices on cliffs, and cave ledges.