It is usually about the size of a soccer ball, and the inside is lined with dry grass, shredded bark, moss, feathers, or other available materials. A single squirrel may have several dreys, and if one becomes infested with fleas or other vermin, she will abandon it and quickly build another.
The squirrel's summer drey can be quite flimsy. In the winter, she will build a sturdier, thicker drey lodged on a large branch close to the tree trunk, or she may move into a cozy nest in a hollow trunk.
Don't forget, October is Squirrel Awareness Month!
Cross-Section View of Drey