Suddenly a squirrel skirmish erupts, perhaps due to a territorial incursion, and the chase is on. Down the tree trunk, head first, two squirrels flash like lightning, until the intruder is banished to another tree. The triumphant winner scurries back to his branch in the oak, surveying the surrounding territory like a king surveying his realm. Within the order of Rodentia squirrels form an extensive family, Sciuridae , consisting of 50 genera and 260 species. The squirrel family includes animals ranging from the size of a mouse to some larger than cats.
Squirrels inhabit every continent except Australia and Antarctica.
They have developed a wide variety of body forms that equip them for life in a broad range of habitats, from semi-arid deserts and prairies to alpine regions, tropical forests, town gardens and parks. Some members of the family, such as marmots and prairie dogs, burrow underground for shelter and spend their days on the ground, while others live primarily in trees, inhabiting various elevations of the forest canopy. Nocturnal members of the family, flying squirrels, have developed a flap of skin between their legs and body, that allows them to glide through the forests rather than leap from branch to branch. Several of the most familiar, the gray and red squirrels, Sciurus carolinensis and S. vulgaris , may be seen in enclosures behind the Small Mammal House. The red squirrels, smaller than their gray cousins, are most active early in the morning shortly after sunrise.