More than any other animal except for humans, bird are known for their ability to build. Birds build nests in which to lay their eggs. For some birds, nests provide shelter from rain and cold. Bird nests vary greatly in complexity. Some birds build no nests at all, while others build simple nests of twigs or leaves. Perhaps the most familiar type of nest is the cup-shaped nest built in trees by many species of birds. The most complex type is the enclosed nest. Basically, the enclosed nest is a cup-shaped nest covered by a dome-shaped roof. Enclosed nests are solidly built and intricate. They have multiple chambers, and several generations of birds may live there for years. Even after the builders of these nests abandon them, they may be used by other birds or other types of animals.