Birds' nests are amazing structures in various sizes and styles. Birds stay in nests on average from two to 10 weeks, depending on the bird and their development. Some raptors spend up to 90 days, while precocial birds (mostly developed birds at birth) only spend hours in the nest after hatching. Some birds reuse their old nests every year.
Learning about the different styles of nests can help birders better appreciate birds' engineering ingenuity, and looking at different nest types can be an excellent clue for proper bird identification. People can also help birds make nests by leaving behind the scraps they need.
Why Birds Build Nests
No matter the bird's style, all nests serve the same purpose: to protect eggs and hatchlings. There are different ways nests do this, including:
- Cushioning: Many nests are lined with soft plant fibers, animal fur, fine grasses, feathers, moss, and similar materials that cushion the eggs. This cushioning protects the eggs even when a brooding adult moves around on top of the nest. Most nests also have a degree of flexibility or elasticity to protect growing hatchlings without breaking or collapsing.
- Shelter: Nests help shade and protect eggs and chicks from poor weather. Some birds do this by creating nests that include roofs or overhangs. More often, however, the nest is positioned in a sheltered location out of the wind and protected from the worst of the hot summer sun, stormy winds, or drenching rains.
- Camouflage: Eggs and chicks are exceptionally vulnerable, and most nests are constructed to help keep the birds and eggs hidden from predators. Birds may do this by building their nest in a hidden location or using materials to help conceal the nest. Bits of bark, lichen, moss, or other materials are often used to decorate the outside of the nest as camouflage.
In some cases, nests also help attract mates, and some birds build especially elaborate nests or may start several nests in different locations to better appeal to a mate. Once the partnership is formed, the nest construction will be finished, and the eggs laid.
Bird Nest Designs
There is great variety among nests types. While the same species will always make the same nest structure, it's usually because it fits their needs, size, and environment.
Eagles reuse their nests yearly, continuously adding to their nests. They are known for having some of the most enormous nests in the avian world. According to Guinness World Records, the largest bird's nest was built by a pair of bald eagles in St Petersburg, Florida, measuring 9 feet and 6 inches wide and 20 feet deep. It weighed more than two tons (4,409 lb).
A simple cup-shaped nest is the most typical, common nest type. Cups are often positioned along tree branches or tree forks or may be nestled on ledges or in numerous unique places. The cup's overall size, dimensions, and depth may differ, and some birds build distinct inner and outer cup layers.
Birds that build cup nests: Barn swallows, ruby-throated hummingbirds, yellow warblers, American robins, and many different passerines
A basic scrape is a shallow depression on the ground without much nesting material, though it may have a light lining of down, grass, pebbles, weeds, or other debris. Scrapes are popular nest types for terrestrial birds or birds that prefer open habitats that lack abundant trees, such as shorebirds or tundra species.
Birds that build scrape nests: Common ostrich, killdeer, American avocet, Arctic tern, and many shorebirds
A nesting burrow is dug into the ground and may be a shallow cave or could have a long tunnel leading to a nesting chamber. These nests are often excavated in a soft material such as loose dirt banks or guano accumulation. The inner nesting chamber may be lined with some material or could be bare. Birds may excavate their burrows or may usurp suitable holes from other animals.
Birds that nest in burrows: Atlantic puffin, burrowing owl, great hornbill, barbets, kiwis, and many kingfishers
A mound nest is built on the ground but is a large accumulation of nesting material in a tall cone or bell-shaped structure. The height and diameter of the nest mound will vary. The eggs may be nearly buried in the nest, which helps provide additional protection and insulation, or they can rest on top of the mound.
Birds that build mound nests: Horned coot, Adelie penguin, malleefowl, and most flamingo species
Cavity-nesting birds are common and will either excavate their nesting cavities or use natural cavities in trees, snags, or cacti. Holes in telephone poles or even nestled in gaps in houses and birdhouses are also great options for cavity-nesting species. The interior cavity may be bare or lined with various materials, and some birds may even build loose cups inside the hole.
Birds that use nest cavities: Eastern bluebird, house sparrow, most woodpeckers, many parrots, tits, and chickadees
A platform nest is a relatively large, bulky structure often built of larger twigs or sticks. The surface is typically flat or may have a very shallow depression, but not enough to be considered a deliberate cup. Many birds reuse platform nests for many years, often adding material to the nest each year.
Birds that build platform nests: Bald eagle, osprey, great blue heron, white stork, and many other raptors and large wading birds
Pendant or Suspended
Pendant nests are elaborately woven sacks that dangle from branches, giving birds in the nest excellent protection from predators. Some are not suspended far from the branches, while others may hang several feet below their attachment point. Birds enter the nest through an entrance on the side.
Birds that build pendant nests: Baltimore orioles, caciques, oropendolas, and most weaver bird species
A sphere or dome nest is almost completely enclosed and provides great protection and camouflage. The trade-off, however, is that these nests are often on the ground or in low areas and may be more susceptible to predators. The nest entrance is typically on the side, protecting from the rain.
Birds that build sphere nests: American dipper, marsh wren, winter wren, ovenbird, and different meadowlarks
Some waterbirds build floating nests from mud, cattails, reeds, and other aquatic vegetation directly on top of the water. They anchor the nests to reeds and vegetation to keep them concealed and stop them from drifting away.
Birds that build floating nests: Loons, grebes, coots, and gallinules
Many birds flock together and nest near each other, developing nesting colonies; others build one giant nest complex with separate nesting compartments within, like the social weaver in Africa that creates one nesting compound that can house 400 to 500 birds.
Birds that build nest colonies: Social weavers, parakeets
What Are Bird Nests Made Of?
In some cases, you can identify a bird by what the nest is made of. House sparrows prefer to collect nest material found close to their nest. They use straw, grasses, and small twigs to make their nests, sometimes including found feathers, string, and paper. Starlings use fresh-cut green leaves from the spring pruning of shrubs. They may also use moss raked from a lawn or scraps of found wool. House martins, song thrushes, and blackbirds use mud to construct their nests.
Birds like chaffinches and long-tailed tits rely on spiders for food and their webs for construction materials. They also use moss and lichens to line and camouflage their nests.
Others might use binding materials, such as saliva, to build or help support the nest. For example, swiftlets make their nests entirely from solidified saliva to construct their cuplike nests.
Birds in cold climates might line their nests with insulating materials, such as grass, to help keep the eggs warm. Birds in warmer regions might use rocks instead because the gaps allow better air flow to keep the eggs cool.
Birds Without Nests
While birds can be creative architects, several bird species have no nests and don't even scrape the ground before laying an egg; they find a spot and lay. Some species, such as the peregrine falcon, common murre, nightjar, short-eared owls, and emperor penguin, lay their eggs in the open or a relatively secluded spot without having a nested structure.
Some birds, like the potoo, use an unusual spot like the top of a tree stump, while a fairy tern will use a bare tree branch. These birds have adaptations like only laying one egg, both male and female incubating the egg, or having longer feet and sharp claws to keep the egg from rolling off a tree branch.
Other birds, such as the brown-headed cowbird, are brood parasites that lay their eggs in other birds' nests, abandoning their parental duties altogether.