A bird nest is the spot in which a bird

Bird

Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...

 lays and incubates

Avian incubation

Incubation refers to the process by which certain oviparous animals hatch their eggs, and to the development of the embryo within the egg. The most vital factor of incubation is the constant temperature required for its development over a specific period. Especially in domestic fowl, the act of...

 its eggs

Egg (biology)

An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...

 and raises its young. Although the term popularly refers to a specific structure

Structures built by animals

Nature abounds with structures built by animals other than humans, or animal architecture, as it is commonly termed, such as termite mounds, wasp and bee hives, burrow complexes of rodents, beaver dams, elaborate nests of birds, webs of spiders and many more.Often, these structures incorporate...

 made by the bird itself—such as the grassy cup nest of the American Robin

American Robin

The American Robin or North American Robin is a migratory songbird of the thrush family. It is named after the European Robin because of its reddish-orange breast, though the two species are not closely related, with the European robin belonging to the flycatcher family...

 or Eurasian Blackbird, or the elaborately woven hanging nest of the Montezuma Oropendola

Montezuma Oropendola

The Montezuma Oropendola, Psarocolius montezuma, is a New World tropical icterid bird. It is a resident breeder in the Caribbean coastal lowlands from southeastern Mexico to central Panama, but is absent from El Salvador and southern Guatemala. It also occurs on the Pacific slope of Nicaragua and...

 or the Village Weaver

Village Weaver

The Village Weaver , also known as the Spotted-backed Weaver or Black-headed Weaver , is a species of bird found in much of sub-Saharan Africa...

—that is too restrictive a definition. For some species, a nest is simply a shallow depression made in sand; for others, it is the knot-hole left by a broken branch, a burrow dug into the ground, a chamber drilled into a tree, an enormous rotting pile of vegetation and earth, a shelf made of dried saliva or a mud dome with an entrance tunnel.