That means they stay awake at night and sleep in the daytime. Tree squirrels spend most of their lives in trees. They race along branches, leap from tree to tree and go up and down, down and up, the tree trunks. Tree squirrels build nests in tree trunk holes or high up in the branches. Here they sleep, stay out of bad weather, and raise their young.
Many squirrels live in burrows under the ground instead of in the trees.
They look a lot like tree squirrels, except their tails are often smaller and less furry. Some variety of ground-dwelling squirrel is found almost everywhere. Other squirrels that live in the ground are named chipmunks, prairie dogs, woodchucks, and marmots. Chipmunks are among the smallest of the ground-type squirrels, some weighing only an ounce or two. They always have stripes on their faces and their sides.