Tree squirrel Tree squirrel Tree squirrels are the members of the squirrel family (Sciuridae) commonly just referred to as "squirrels". They include over a hundred arboreal species native to all continents except Antarctica and Oceania. They do not form a single natural, or monophyletic group; they are related to others in the squirrel family, including ground squirrels, flying squirrels, marmots, and chipmunks. The defining characteristic used to determine which species of Sciuridae are tree squirrels is dependent on their habitat rather than their physiology. Tree squirrels live mostly among trees, as opposed to those that live in burrows in the ground or
Arboreal locomotion gravity. Many arboreal species lower their center of mass to reduce pitching and toppling movement when climbing. This may be accomplished by postural changes, altered body proportions, or smaller size. Small size provides many advantages to arboreal species: such as increasing the relative size of branches to the animal, lower center of mass, increased stability, lower mass (allowing movement on smaller branches), and the ability to move through more cluttered habitat. Size relating to weight affects gliding animals such as the reduced weight per snout-vent length for 'flying' frogs. Some species of primate, bat, and all species of sloth achieve