If you leave a wooden box outside near a tree trunk, you might find a surprise—a dormouse could be nestled inside! But humans should never go near a nest unless it is abandoned.
Like dormice, squirrels use nests to protect their young. These nests often are ball-shaped, and made from twigs and leaves. Although squirrels do not hibernate during the winter, they use their nests for shelter from the cold. Squirrels also use their nests to care for their young. The young stay in those nests until they are six weeks old. The mother changes the bedding of the nest regularly to keep it clean.
The nests of dormice are made of hay, bark fibers, and plant material. Dormice weave these materials into round or oval-shaped nests. These nests help dormice hibernate all winter, until April or May. In the warm months, dormice sleep in the nest during the day.
[Source: National Geographic: Animal Tracks and Signs]