A nest is a structure built for certain animals to hold eggs or young. Although nests are most closely associated with birds, members of all classes of vertebrates and some invertebrates construct nests. They may be composed of organic material such as twigs, grass, and leaves, or may be a simple depression in the ground, or a hole in a rock, tree, or building. Human-made materials, such as string, plastic, cloth, or paper, may also be used. Nests can be found in all types of habitat.
The elaborate bird nest of a baya weaver
A night heron building a nest
Swans with nest and eggs at Lake Constance
A dusky woodswallow parent feeding chicks in a nest at Mortimer Bay, Tasmania, Australia.
Nesting behavior refers to an instinct in animals during reproduction to prepare a place with optimal conditions for offspring. The nesting place provides protection against predators and competitors that mean to exploit or kill offspring. It also provides protection against the physical environment.
Bird's nest in grass
Groundhog gathering nesting material for its warm burrow
Wood rat (Neotoma lepida) nest at Joshua Tree National Park
Tawny mining bee (Andrena fulva) nest entrance