8 Animals that Build Nests (It’s Not Just Birds!)

Birds

It wouldn’t be a list of animals that build nests without first highlighting the species most well-known for natural architecture. Not all birds build nests, and, of those birds that do, not every nest is equal. 

For example, compare the nests built by the California condor to that of the ruby-throated hummingbird.

The largest bird in North America, the California condor most often nests in natural cavities along cliffs, including caves. However, they may also nest in large trees, such as the coast redwood. Occasionally, California condors may lay their eggs directly on the ground if nesting in a cave or on a cliff ledge. When they do build a nest, however, they will create a loose nest made of gravel, leaves and barks, or even bones. The nest of the California condor is, on average, around 3 feet in width, with a depth of 8 inches.

In comparison, ruby-throated hummingbirds will also build a well-constructed nest, though they are much smaller than that of the California condor. These birds will build their nests on slender branches or man-made structures, such as chains or extension cords. They create an inner cup around the size of a thimble using thistles or dandelions. The pliable nature of these materials allows for the female to shape it as she pleases.

Regardless of shape or structure, the nests of birds, like many other animals, serve a shared purpose: providing protection and shelter for offspring. Many of the animals that build nests may not use them year-round, instead only building these intricate and interesting structures during the breeding season. 

Tree Squirrels

When looking into a tree and seeing a large nest, it can be easy to think that the nest may belong to a bird. However, while this is always a possibility, tree squirrels will also construct their nests in trees.

There are two main types of tree squirrel nests. The first is the most common to see: the leaf nest. These nests are comprised mainly of leaves, although small twigs may be added throughout. Most often, squirrel leaf nests are found high up in trees, around 20 feet off the ground. Here, they are built in the fork of large branches. This helps provide stability for the nest and protection from strong winds and storms. Although these may look similar to the nests of some bird species, you can identify them because of their large size.

The second type of tree squirrel nest is those constructed within the cavities of trees. Most often, these cavities are created first by woodpeckers or other species. Natural processes may also lead to the creation of these cavities. These act as the preferred home for squirrels because of the protection they provide.

Raccoons

Squirrels aren’t the only mammals to make nests. In fact, raccoons may also build nests. Their nests are often found in trees, cavities, and similar locations. This species is opportunistic, in diet and habitat. As a result, with their natural wild habitats shrinking, you may also find them nesting in human areas such as chimneys or attics. Living in these areas also provides raccoons with the option to forage for food among trash cans and pet food, as well.

Raccoons will build their nest with a variety of materials, depending on what is available. As for many animals that build nests, leaves are a common option due to their availability, softness, and insulation qualities. However, while they may build their own nests, when available, raccoons will choose to take over nests abandoned by squirrels and birds. 

Frogs

The grey foam-nest tree frog (Chiromantis xerampelina) is one example of a non-mammal or bird species that creates a nest. However, in contrast to the nest-building animals explained above, these frogs do not build their nest using leaves.

Instead, the grey foam-nest tree frog has a different approach to keeping its offspring safe. The nest-building process begins with the female excreting a thick, mucus-like substance. As she excretes this substance from the cloaca, she uses her hindlegs to introduce air into the liquid, whipping it into a bubbly, foamy froth. This substance is rather elastic, allowing the female to easily manipulate it into a nest. These foamy nests are found over water, where they will house the offspring until the eggs hatch. Then, the tadpoles will drop into the water where they will develop into adult, nest-building frogs to continue the cycle.

Fish

Nest-building is a common behavior among freshwater and saltwater fish. However, unlike in many avian and mammalian species, it is the male that builds the nest. Nests are often used as a token of courtship, built in such a way as to impress potential mates. 

Nests will vary depending on the species. Betta fish, for instance, will build a foam nest similar to that of the grey foam-nest tree frog. However, instead of using a mucus-like substance hung on plants above water, betta fish will blow bubble nests that gather on the surface of the water.

Other types of fish nests include mound nests, nests built in empty shells, burrows, and woven nests.

Alligators

One of the most surprising animals to build nests is the alligator. As with all reptiles, alligators start life as an egg. Alligators are soft, lacking the stiff outer shell of avian eggs. Because of this, the female alligator, who presents strong maternal instincts, will build a nest and care for her young until they are old enough to become independent. 

Alligators will build their nests on the shores of marshes and swamps, several feet away from the water and often in areas with an abundance of vegetation. An alligator nest is often around 6 feet in diameter. The materials comprising the nest may vary based on what is available, but vegetation and sticks are often used.

Sea Turtles

Among reptiles, sea turtles are likely one of the most well-known animals that build nests. Each year, during the breeding season, coastal organizations and agencies spread an abundance of information about these species’ nest-building behaviors. Some groups may even go out onto the beach to locate and mark sea turtle nests to help prevent human interference. 

However, what does a sea turtle nest look like, and how do they build it?

Sea turtles take an entirely different approach not only to parent but nest-building than alligators. Because the female will leave her eggs, and consequently the offspring to fend for themselves, a protected nest is essential. During the night, the female sea turtle will emerge from the sea and crawl onto the beach. Little is known about why sea turtles will choose one beach over the other. She will construct what is known as a body pit by using her flippers to move sand. She will then lay her eggs into the cavity and cover it once more before returning to the ocean. 

Dinosaurs

Although no longer roaming the Earth, dinosaurs, like other reptiles, once built nests. In fact, many remnants of fossilized dinosaur nests have been uncovered, including eggs. Although there is still much to be learned about the nesting behaviors of dinosaurs, it is likely they built nests and cared for their young in a way more similar to alligators and birds than sea turtles.