Shhh, it"s sleeping. But don"t confuse that with hibernating. A tree squirrel, like this red squirrel in Scotland, doesn"t hibernate during the winter. Hibernating is more of a ground squirrel trait. But the red squirrel is particular about where it sleeps, mostly building its nest, or drey, high above the ground in the cavity of an evergreen tree. Nests are often lined with soft materials such as leaves, moss, and grass. This little sleeper is using its bushy tail to keep warm, with the help of some lichen and pine needles.