Nests of Birds

nest of birds
Nests of the Chestnut-collared Swallow (Petrochelidon rufocollaris) made of mud mixed with plant matter.

The Nest of Birds

Definition: A bird nest is a place and structure where birds lay their eggs, incubate them, and rear the nestlings. Nest can be built and attended by a pair or multiple individuals working together in a cooperative breeding system. A bird nest can be a simple depression on the ground or an elaborate hanging dome, all of which protect the eggs and young from the elements and detection by predators.

Nests designs are specific to taxonomic groups. Member of a bird family build nests of similar design.

Because birds descended from dinosaurs called theropods, birds and reptiles show similarities in their nesting biology. However, birds are much more advanced in courtship displays to find a mate, construction and positioning of their nests, and the care of their progeny. In this article, we talk about the characteristics of the most common types of bird nests.

General Aspects of the Nests of Birds

The most common type of nest built by birds is the cup-shaped nest. But there are many shapes, sizes, substrates, and materials that birds use to make their nests. The shape, material used, and nest positioning respond to the birds’ basic needs: to protect the eggs and chicks from inclement weather and, perhaps more importantly, from predators.

Types of Nests

The choice of a nest site and its construction are important because this will be where the egg-laying, incubation, and caring for the young activities occur. The nest is a structure built or conditioned by the parents, although sometimes they can use a natural depression of the land or existing nest. Depending on the nest’s location, parents may camouflage the nest or cover the eggs with twigs and dead leaves to conceal them from possible predators.

nests of birds_oystercatcher
Nest in a depression in the ground. See the nest with two eggs in the lower center part of the photo.

Common Types of Bird Nests 

Nest in a Depression on the Ground

This is one of the simplest constructions of nests and consists of a small depression in the ground or vegetation. This depression has to be deep enough to prevent the eggs from rolling out of the nest. The depression on the ground is sometimes reinforced or lined with branches or even small rocks. Depression in the ground as nests are used by quails, most shorebirds and seabirds, rails, and nightjar.

nests of birds_megapod
A mound nest consists of a pile of plant material and dirt with buried eggs. The decomposition of the material generates heat, which imitates the incubation process. Nest of a Megapode (Leipoa ocellata). Photo: Glen Fergus/Wikipedia.

Nest in a Mound

This particular form of nesting includes the construction of a pile of plant material and dirt. The eggs are placed in the middle of this pile and buried with more branches, dirt, and leaves. The parents abandon the mounds and eggs. The decomposition process of organic matter radiates heat, which incubates the eggs until they hatch. The chicks never know their parents, and they find food and take care of themselves from the moment they hatch. The size of these nests can reach sizes of more than 100 m2 of material. Mound nests are exclusive to the Megapods of Australasia.

nests of birds_burrow
A mot-mot’s burrow nest is located in a vertical dirt bank inside the forest. 

Nest in a Burrow

Most birds that construct this type of nest dig their own burrow, but others use abandoned or existing burrows dug by other animals. This type of nest effectively protects the eggs and chicks from the elements while minimizing the probability of detection by predators.

nests of birds_barbet
Female of a Versicolored Barbet in a cavity in a dead and rotten trunk. Barbets can dig their own cavities as well as use already-made cavities.

Nest in a Cavity

Cavity nests consist of a chamber located in the wood of living or dead trees or trunks of arborescent ferns or cactus. Nests in cavities also include chambers dug in termite nests. The nests in cavities in the wood are found in any region where there is wood as a substrate. The nests in termite nests are mostly restricted to tropical regions where termite nests are prevalent. The birds using cavity nests include woodpeckers, toucans, trogons, barbets, and a few species of the Tyrannidae family (flycatchers), which use existing cavities.

nests of birds_bowl
Cup or bowl-shaped nests are the most common type of design. 

Nest in Cup or Bowl

The nests in the shape of a bowl or cup are mostly circular or semi-circular in shape. It can also be said that this type of nest has the shape of a cup or half a cup. The materials used for constructing this type of nest vary between purely plant material and threads of spider webs or caterpillars, mud, lichens, saliva that the bird produces, or a mixture of mud or saliva with plant materials.

Depending on the materials used, these nests can be flexible or rigid. They can be placed on a simple branch, in crossings of branches, or on forks. Nests made with saliva can be glued to vertical rock walls or similar substrates. Cup-shaped nests are the most commonly built by most birds. 

nests of birds_osprey
A platform nest is generally re-used for many years. The nesting pair adds a layer of nesting material each season, making the nest grow taller and wider. Photo: Neil Demaster/Flickr.

Nest on a Platform

As its name says, platform-type nests are in themselves an accumulation of plant material with a flat surface with a depression in the center to house the eggs and prevent them from rolling out of the nest. The platform nests are generally placed on bifurcations of large branches between which the material is first placed as a base. Then, additional material is added.

In general, platform-type nests are used by the same or different pairs for many breeding stations. The users add a new layer of nest material, and this is how the nest grows in size every year. The nest can grow in size and add weight to the point that it causes structural damage to the substrate that supports them. If the nest falls due to excessive size and volume, it is usually reconstructed using the same supporting structure. Birds that make platform nests include herons, storks, and birds of prey.

nests of birds_nest hanging
A Russet-backed Oropendola (Psaracolius angustifron) arriving at its hanging nest. Hanging nests are prevalent in the Icteridae family.

Hanging Nest

The hanging nests are the most sophisticated among the nests of birds. There are many types of hanging nests, and they usually have an upper part of varying lengths woven to the support branch, a chamber, and an entry at variable locations on the nest. The entrance can be close to the part where the nest is woven to the branch, on one side of the chamber, or at the bottom of the nest. In some hanging nests, the entrance is covered with nest material, making it difficult to detect where it is located.

The shape, size, and placement of hanging nests are variable and specific to individual bird families. Most species within the Icteridae family (Orioles and caciques) and some of the Tyrannidae family (flycatchers) build hanging nests.

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The spherical nests have a roof with a lateral entrance that is usually camouflaged.

Spherical Nest

Spherical nests generally have a spherical shape or a shape that conforms to the structure in which they are built. A spherical nest often looks like an accumulation of twigs and leaves with a concealed, often difficult to detect, entrance. Inside, this type of nest has a very well woven cup where the eggs are placed, and the chicks grow. The spherical nests are usually placed in hidden places, and the non-striking appearance responds to the purpose of going unnoticed by predators.

nests of birds_colonial
Gannet Piqueros nesting colony. Photo: Shellie / Flickr.

Individual Versus Colony Nesting

Most small birds that nest individually must deal with the risk of predation of their clutch and chicks by placing and building a concealed nest. Large birds have exposed large nests because they can defend their eggs and chicks against most predators.

Small birds also build an exposed nest in colonies. Birds nesting in colonies can detect and defend their nest more easily by having many more eyes watching, and many individuals attack and repel predators from their nests.

Another advantage of nesting in colonies is that synchronized breeding produces many eggs and offspring simultaneously. Predators can only take so many eggs and chicks at one time before they are satiated. Predation in colonies results in a proportionally smaller loss at the population level than if the same birds would nest individually over a more extended period of time.
Colonies can also serve as an information centers. Birds that were not successful at finding food can follow those birds that can find the food better.

References:


  • Gill, F. (1995). Ornithology. W.H Freeman and Company, New York.
  • Wimberger, P. H. (1984), The use of green plant material in bird nests to avoid ectoparasite», Auk 101: 615-616

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