Bird Nest Identification – 12 Types and How to Spot Them
Birds – far more than any other animal besides humans – are notable for their tendency to build a home. A home in which to raise their young… and in some cases to use all year round.
Bird nests are a tool used by nearly a whole class of animals. Every year, billions of birds put in an amazing amount of effort to construct some of the most elaborate creations in the animal kingdom.
And did you know that in most cases, it is possible to identify the bird by its nest?
In this article, we will show you pictures of some very interesting bird nests.
We will also help you identify the nest that you might have seen in your backyard or on the trail and wondered, to which type of bird does this nest belong?
For the purposes of this article, we will define a nest as anything constructed by a bird or where a bird lays its eggs.
This is the broadest possible definition and allows us to discuss the full extent of bird nesting habits.
Even before they build it, birds have to select the right location for their nest. Once the location is selected, it can take them up to two weeks to build a nest, though, some birds can do it in only two days.
Types of Bird Nests
For the purpose of classification, bird nests can be categorized into 12 general categories.
- Birds With No Nest
- Architecture But Not Nests
- Simple Birds Nests
- Cup Shaped Nests
- Enclosed Bird Nests
- Hanging Bird Nests
- Floating (Aquatic) Bird Nests
- Edible Bird Nests
- Mound Nests
- Holes in the Ground
- Birds That Build Mud Nests
- Holes in Wood
Birds With No Nest
The simplest type of nest of course, is no nest at all.
Quite a few birds do not build any nest, though they do make a choice of where to lay. Beyond this is a simple scrape in the ground.
Nightjars (Caprimulgidae) do not make even a scrape. They lay their two eggs directly onto the ground.
While short-eared owls, Asio flammeus, lay simply on some trampled vegetation.
Many waders, such as Plovers, lay in a simple scrape on bare ground, relying on the cryptic coloration of their eggs to protect them from predation.
Some of the more unusual examples of no nest laying include the Potoos, Nyctibius spp., which lay their single egg on top of a broken-off tree stump. The bird then sits on top of the stump, with its head pointing to the sky. In this position, it looks like an extension of the dead timber. It generally chooses stumps of similar diameter to itself.
Even trickier are the ‘nests’ of Fairy Terns, Sterna nereis, another species that lays only one egg. The egg is laid on a branch or a rock face, generally on an area too small to support 2 eggs.
Laying the egg in a position where it won’t roll off is tricky… and young birds often lose their first attempts before they get the hang of choosing a safe spot.
Fairy Terns have two adaptations to help them survive this seemingly precarious nesting habit.
The adults have evolved to be very careful when settling on and getting off the egg – both sexes incubate the egg.
The second adaptation is that young Fairy Terns have disproportionally large feet and very sharp claws which help them hang on tight to the branch.
The master of no nest nesting, however, has to be the Emperor Penguin (Aptenodytes forsteri).
These birds nest in the Antarctic, where during the winter the temperature can fall to less than -40 degrees C. They nest well inland and when the female has laid a single egg, she leaves for the coast to feed.
Meanwhile, the male has immediately taken over the care of the egg by moving it up onto the top of his feet. He has special folds of skin on his belly which enfold the egg, keeping it safe against all the severity of the elements.
Here he stays – a living nest with an egg on his feet – for the next 60 days, without a meal or much movement at all until his mate returns and the egg hatches.
During this time he has maintained the internal temperature of the egg at 40 degrees above zero degrees C, as much as 80 degrees C higher than the surrounding ambient temperature.
On the other hand, Gentoo penguins make a nest of pebbles and lay two eggs. You can see in the photo one chick and one un-hatched egg.
Note – this image was previously classified as an Emperor penguin but thanks to Alex Taylor (from www.ravenwest.ca) for pointing out the error and helping us rightly identify this beautiful bird as a Gentoo penguin!
Bowers: Architecture But Not Nests
After looking at birds that don’t build any nests at all, we look at birds that build something, it is just not a nest. One would wonder, what would such structures do? Let us find out.
Bowerbirds have an interesting mating ritual. Male bowerbirds build structures – which though often involving great effort – are not actually nests.
These bowers, built by 14 of the 18 known species of Bowerbird, are stages or advertisements. They are built to attract females, which presumably are attracted to larger more ornate structures and which judge a male on his collection of treasures.
The real nest is built by the female after she has been mated by her chosen male. She incubates the eggs and raises the young on her own, while the male stays with his bower to try and attract more females.
Bowerbirds build different sorts of bowers even within one species. Different populations build different designs and collect different ‘treasures’.
Some simple bowers consist of an avenue of twigs – in which the male bird walks up and down to display himself to the female. Some of these may have sticks painted with yellow, brown or purple plant juices.
More complicated bowers involve towers of sticks and display arenas on which the male arranges his collection of treasures and around which he displays himself.
Treasures include feathers, particularly blue ones, snail shells, beetle wings and heads, bones, flowers and anything else which takes the bird’s fancy.
This may include man-made objects such as silver spoons, car keys, gun cartridges, tin mugs, buttons and other colourful scraps of material.
The most impressive bower is built by the Vogelkop Gardener Bowerbird (Amblyornis inornatus) from New Guinea.
In some areas, it builds a huge open-fronted roofed hut up to 2.2 m tall and 2 or more meters across. This structure is built by a bird the size of a Song Thrush!
Australasian Bowerbirds are not the only birds to build structures that are not ever destined to be nests.
Others include the Tooth-billed Cat Bird (Scenopoeetes dentirostris), also from Australia, and Jackson’s Whydah (Euplectes jacksoni) from Kenya and Tanzania. Both of these make structures that are quite simple in comparison with some of the bowers described above.
Cat birds line a 1-2 m arena with upside-down fresh leaves, which they cut from vegetation with their toothed bill.
Jackson’s Whydah is a lekking species in which each male has a personal arena about 1 m across with a pseudo-nest. Mating normally takes place during the inspection of the pseudo-nest by the female.
Like all lekking species, the female builds the true nest later, incubates the eggs and raises the young on her own.
Simple Birds Nests
Simple bird nests are constructed of plant material, sticks or stones. They are quite a common type of bird’s nest and like nestless birds above, all the birds that use them are non-passerines.
The best example of a simple stone nest is that of Adelie Penguins. The nest is basically a mound of stones that serves as protection against flooding.
Most simple nests, however, are made of sticks and twigs built into a simple platform. Which, though it may have a depression in the middle and be quite extensive, does not really have an inside and outside.
A common example of a simple platform nest are those constructed by many doves and pigeons.
Those, like that of the Ruddy Quail Dove, Geotrygon montana, are often a simple lattice with just enough twigs to support the egg.
In these cases, the egg can often be seen through the nest from beneath. Sometimes a flimsy lining of grass and rootlets may be added and in some cases, the lining may be more complete.
Another bird that builds a simple platform is the Hoatzin from S. America.
Yet another well-known example of a platform nest and one which is more substantial than a pigeon’s is that of the European White Stork, Ciconia ciconia, which has for centuries nested on chimneys and specially erected platforms across Europe.
More complicated than the previous nests, it consists of sticks interwoven then plastered to some extent with mud. A depression in the middle is often lined with grass or paper.
Mute Swans’ (Cygnus olor) nests are an example of a different form of simple nest construction.
They do not carry any material to the nest. Instead, they choose the site, they flatten the vegetation and lay the eggs. Then, the female swan builds up the nest around her by dragging material within reach so that eventually it forms a rampart that surrounds her.
Other birds which build simple nests include many gulls and herons.
The most spectacular nests in this category are those built by various eagles. Most bald eagles build their nests in trees. In fact, some of these nests can be so heavy that they damage the tree supporting them.
The largest nests on record, however, are those of the Golden Eagle, Aquila chrysaetos, which tend to build a new nest on top of the previous year’s nest. This results in huge structures often containing more than a ton of material.
Fortunately, Golden Eagles prefer rocky alpine crags as nest sites – which can often support these massive structures more easily than a tree.
Golden Eagles are known to adorn their nests with sprigs of green boughs throughout the nesting season, well after the young have hatched. Many researchers believe that this is evidence of a rudimentary aesthetic sense.
Cup Shaped Nests
The next step up from a simple platform nest is a cup-shaped nest.
These are the most numerous type of bird nests and one that most people consider the typical “a bird’s nest”. They are distinguishable because they have a definite inside as well as outside and the inside is normally lined.
Cup-shaped nests require more effort to make as compared to the previous two categories. But they also give more protection to the eggs and young birds.
Cup-shaped nests can be built in a variety of places, but normally they are built in trees. Often the simplest form is wedged into a ‘Y’-shape division of a branch, but many birds bind or cement them directly to a bough.
The smallest cup-shaped nests belong to the Hummingbirds and Woodstars, which build perfectly shaped thimble-sized nests of moss and cobwebs.
Often the female bird flies during the whole nest construction, hovering here and there while building up the shape.
Different birds’ nests take different lengths of time to build. Some are completed in a day or two, others take 2-3 weeks to complete.
Birds build cup-shaped nests using a mixture of substances. Redwings, Turdus iliacus, build nests of leaves, grasses and fine twigs cemented together and then lined with moss and feathers.
Not all cup-shaped nests have a soft lining though. The female Song Thrush, Turdus philomelos, lines her nest with mud, dung and rotten wood – all of which is cemented together to form a very hard inner surface.
The other extreme to the delicate nest of the Hummingbirds, are the large scraggly looking structures built by crows.
The initial outside of a crow’s nest is built of twigs and grass cemented together with mud.
Within this rough exterior, the crow makes a deep cup and lines it with moss and feathers. Crows’ nests often look rough and ready, but inside they are warm and comfortable.
Other birds, like Kestrels, Falco tinnunculus, are happy to use a crow’s nests once the crow is done.
Enclosed or Domed Bird Nests
Enclosed bird nests are more elaborate cup nests with higher walls and a hole for the birds to enter and exit.
These nests offer better protection to the eggs and young chicks because they are more enclosed.
As with all these categories of bird nests, there is a gradient of complexity and quality among domed nests. For example, Chiffchaffs Phylloscopus collybita, make fairly simple enclosed nests that just have a loose roof.
Similarly, Magpie (Pica pica) nests have a separte roof that they build over the dome.
Wrens and Dippers are examples of birds that build more complex domed nests.
Many domed nests are quite laboriously built and are very intricate. They also vary a lot in size.
On one of the spectrum, you have the small and beautiful nests of the Long-tailed Tit, Aegithalos caudatus. Long-tailed tits camouflage the exterior of the nest with lichens. They also line the inside of the dome with feathers to provide a soft, warm place for its eggs.
On the other end of the size spectrum of domed nests lies the Hamerkop, Scopus umbretta. The domes of the nests of these birds can be over two metres high and about as wide.
The nest is strong enough to take the weight of a full-grown human. The nests have a long entrance and they can be regarded as a fort in the world of birds’ nests.
Rufous-breasted Castle Builder, Synallaxis crythrothorax, builds one of the most peculiar nests in this category. It is two-chambered and dumbbell-shaped with just one of the chambers being used to rear its young.
Hanging Birds Nests and Woven Nests
Hanging birds nests, particularly woven ones, are perhaps the most admirable of bird architectures. They certainly look very beautiful and most require great skill on behalf of the bird to build.
The simplest type of hanging bird nests are cup-nests slung from an overhead bough by a few cobweb supports, such as the nests of the Goldcrest, Regulus regulus, the Fire Crest, Regulus ignicapillus, and various White Eyes Zosteropidae.
An interesting variation is the hanging cup nest of the Hummingbird (Planalto Hermit), Phaethornis pretrei, which has only a single support cable for its nest. To help keep it stable it has a streamer of grass and cobwebs hanging down below the nest.
Other birds which build hanging nests include the Reed Warbler, Acrocephalus scirpaceus, the Fantailed Warbler, Cisticola juncidis, and the Rock Warbler, Origma rubricata, though this last species is not technically speaking a warbler.
Better known than these are the hanging nests of the Icteridae and Oriolidae.
Woven Nests of Weaver Birds
There are nearly 100 species of weaver birds renowned for their carefully woven hanging bird nests.
These nests tend to be either hung from the tip of a branch or a leaf, or suspended between two twigs.
They are globular in shape with a single entrance hole.
Apart from globular nests, weaver birds also construct kidney-shaped nests and retort-shaped nests which are basically globular nests with an entrance tunnel.
Whatever their shape, nearly all weavers make their nests out of grass and the nests are truly woven.
With the bird moving from side-to-side, poking part of the strand of grass through the wall from the side and then pulling it completely through from the other.
Holes in the Ground
Many birds nest on the ground, with nests of varying degrees of complexity. But far fewer birds nest within holes in the ground.
Nesting in holes would seem to be a better strategy than nesting in the open. One survey of over 180,000 eggs revealed that where non-hole nesters averaged 50% rearing success, hole nesters averaged 70%.
Two main sorts of holes can be distinguished: those which open onto a cliff edge or vertical edge of a river bank (hole in the wall, if you like), and those holes in relatively flat ground.
A second method to differentiate hole in the ground nests is between those birds which dig their own holes and those which make use of other bird or animal created holes.
Commonly recognized birds that nest in cliff-edge holes include House Martins (Delichon urbica), Sand Martins (Riparia riparia) and the widely distributed European Kingfisher (Alcedo atthis).
Interestingly, people installing a birdhouse for a purple martin commonly like to know what direction should it face. In the wild, most puple martins are direction neutral when it comes to choosing a site to make a ole for its nest.
Other kingfishers such as the Malachite Kingfisher, Alcedo cristata, several parrots in the S. American genus Conure and the Ground Woodpecker, (Geocoloptes obroceus) of S. Africa also nest in cliff edges.
More unusual are D’Arnoud’s Barbet, (Trachyphorus darnoudii), and the White-whiskered Soft-wing, (Malacoptila panamensis), which nest in holes dug into flat ground. These sorts of nests may be lined to some extent and are generally dry, well-protected homes.
Excavating your own holes, of course, is hard work and many birds are happy to take possession of someone else’s efforts.
Thus the Shelduck, (Tadorna tadorna), among several ducks, and the Manx Shearwater, prefer to nest in abandoned rabbit holes. Probably not as pleasant as this, but just as labor-saving, Cinclodes and Sharp-tailed Stream Creeper’s (Lochmias nematura) nest in rodent burrows.
In the latter case the burrows are often at the edges of open sewers in Brazilian shanty towns giving the bird the nickname ‘President of Filth’.
Holes In Wood
Mud or earth, of course, is not the only place to make a hole and many birds nest in holes found – or excavated in – trees, cacti and even termite nests.
Making a nest in a hole that already exists in a tree is not really an architectural feat, as it involves little effort on the bird’s behalf. Still, holes in trees, alive or dead, make excellent nest sites and numerous birds use them.
Some, like the Blue tit, Parus caerulea, and several of its relatives, Redstarts (Phoenicurus phoenicurus), the common Starling, Sturnus vulgaris, and many of its relatives, as well as various Flycatchers use existing holes to nest in.
They make very little modification to the hole except to supply some lining as nest material.
Fewer birds excavate their own holes in trees. But of those that do the woodpeckers, with their impressive hammer-drill impersonations are by far the best known.
However, the prize for champion tree hole nester has to go to the various species of Hornbills.
These large birds, with the exception of the two species of African Ground Hornbill, all nest in hollows in trees.
This is no simple matter.
The Great Indian Hornbill is a large bird, nearly a meter from bill-tip to tail-end, which likes to nest between 20-45 meters up the tree trunk.
It can therefore only nest in trees that have a diameter greater than 1-2 meters at this height. Trees this large are now rare in many forests, putting serious pressure on the breeding capability of these birds.
Both males and females help excavate the hole, which needs to be quite extensive to house the female and several chicks for some weeks.
Once the hole is large enough to accommodate the female, she gets inside and helps the male wall up the entrance with a mixture of guano (accumulated bird poop), woodchips and mud.
The female will remain in the hole until the young are ready to fledge. Only a small slit will be left in the mud wall, to allow the male to feed the female and her young.
During this time she not only raises the chicks but also molts all her feathers in one go.
Hornbills are long-lived birds and mate for life, so the male has a considerable vested interest in keeping the female well-fed.
Nesting in holes may be secure from many predators and much of the weather, but it has one drawback.
The warm, humid conditions make ideal breeding conditions for various avian pests and nest parasites such as bird and feather lice, ticks and fleas. Young birds present a captive food supply for the parasites.
Hornbills never use the same hole twice and the need to escape these pests may have something to do with this.
Other favorite sites for nest holes are termite nests and cacti (many of which grow as large as small trees).
Each of these provides an interesting example of commensalism.
Firstly, the Orange-fronted Parakeet (Cyanoramphus malherbi) of Central America nests almost exclusively in mounds built by Nasutitermes termites.
Unlike other birds, mammals, etc, which nest in termite mounds, Orange-fronted Parakeets do not have the nest hole sealed off from the rest of the termite mound.
Soldier termites can wander around the birds’ nest and workers remove the young birds’ feces and any parasites they can find.
Obviously, this is good for the Parakeet, but what the termites get out of it, we don’t know for sure yet.
The second relationship is quite amazing. It is a three way relationship between the Gila Woodpecker, the Elf Owl and the Western Blind snake.
The Gila Woodpecker (Melanerpes uropygialis) nests in holes which it excavates in the famous Giant Saguaro cactus of N. America.
The Elf Owl nests in the same hole with the Gila Woodpecker.
The Elf Owl is tolerated because it has the amazing habit of catching Western Blind snakes and bringing them alive back to the nest.
The snakes are insectivores, so benefit by having a cosy home and free food in the form of avian parasites.
The woodpecker benefits because it gets a reduced parasite loading, thus improving the health of its young.
The owl gets not only a reduced parasite loading and a free nest site, but also protection for its young while it is hunting at night when the woodpecker is roosting in the hole.
One of the strangest types of bird nests – and nesting habits – is that followed by the Megapodes.
On Saro in the Solomon Islands, come nesting time, the already-mated female Scrub Hens leaves the forest where it has lived all year and comes down to the beach to look for an area of sand known as a geu.
In a geu, the sand is heated from below by geothermal energy, as well as from above by the sun.
The female digs a hole about 60 cm (2 ft) deep in this toasty sand. After testing the temperature of the sun with special heat sensors on their tongues (about 33 degrees C or 91 degrees F is best), they lay their eggs and fill in the hole.
The females then return to the forest and expend no further effort on their offspring’s behalf.
This and similar systems by other Megapodes, such as the use of hot springs on Celebes and rotting tree stumps on other Solomon Islands, involve no building effort at all.
However, these facilities are not always available and in Australia and Papua New Guinea various Megapodes use the heat generated by composting organic matter to hatch their eggs.
These incubator composts can be huge and require a large input of effort on the bird’s behalf.
Malleefowl have the most complex nesting habits of all the Megapodes.
A male will commence constructing an incubation mound months before the breeding season.
He first scrapes a hole in the ground using his feet (Megapodes = big feet). The hole is about 0.5 m (1.5 ft) deep.
On top of this hole, he piles all the vegetation he can find, as well as nearby topsoil. The resulting nest mound can be about 5 m (16 ft) across and 1m (3 ft) high.
Similar, but slightly less complex nesting rituals are shown by the Scrubfowl, whose ancient nests may be 12 m (36 ft) across and 5 m (16 ft) high. Brush Turkeys, Alectura lathami, also make nests like this. Their nests are similar in size to a Malleefowl.
Less evolved species such as the Moluccan Megapode, Eulipoa wallacei, simply dig a hole in the soil, lay the eggs and then cover them up. They do not expend any further effort.
(Floating) Aquatic Nests
Though a number of birds build their nests at the water’s edge, several groups build them in the water.
Coots build nests that, though surrounded by water, have a foundation of vegetation that reaches the ground below.
Interestingly the Horned Coot, Fulica cornuta, which breeds on mountain lakes in the Andes where water weed is scarce, builds a foundation of stones – nearly to water level – before building the actual nest.
Grebes can be more adventurous. They build their nests in shallow water – and though they are often anchored at one or two points – they are basically floating on the water.
This is necessary because grebes, which are primarily water birds, are very clumsy on land and find life works better if they can swim right onto the nest.
Two other groups of birds build nests that are completely afloat. These are the Jacanas (Lily Trotters), which build extremely flimsy nests that often sink into the water while the bird is sitting.
Fortunately, the eggs are waterproof, so getting dunked regularly does them no harm.
The others are the 3 species of Marsh Terns (e.g., the Black Tern, Chilodonias niger) which build nests of broken reeds in water up to 120 cm (4 ft) deep. These nests are sometimes anchored to nearby vegetation.
Birds That Build Mud Nests
Mud is often a common resource and it makes sense that birds somewhere should have evolved to use it for nest building.
Flamingos are well-known and colorful birds that build very basic nests of mud. You can find them building up piles of mud and feces in the middle of the toxic lakes of Africa.
In fact, flamingos can do more than thrive in highly alkaline water. They can also drink near-boiling water.
Flamingo nests are basically hollow mounds with a depression in the center. They are not built all at once, but some mud is built up above water level and as this dries more is put on top.
Flamingo nests can be as much as 45 cm (1.5 ft) high. There is no lining in these nests except the mud.
Many birds build cup-shaped, mud nests which rest on boughs of trees. These nests often have straw or grass mixed in with the mud, making them stronger when dried – much like ancient bricks. Normally, these birds’ nests are lined with grasses, leaves, moss and feathers.
Some examples of cup mud nests in trees are the Magpie Bird, Grallina cyanoleuca, and the Willie Wagtail, Rhipidura leucophrys, from Australia.
Two other Australian birds, both communal breeders, the Apostle bird, Struthidae cinerea, and the White-winged Chough, Corcorax melanorhamphos, also build mud nests.
In East Africa the Spotted Morning Warbler, Chichladusa guttata, also builds cup mud nests.
A number of birds build more unusual mud nests.
In southern Europe the Rock Nuthatch, Sitta neumayer, builds a large mud nest on the sides of cliffs, that looks like a rounded volcano on its side, i.e. if the cliff was level ground, the volcano would be the right way up.
In South America, the two species of Oven birds, Furnarius rufus and F. cristatus, build perhaps the most complicated mud nests of all.
The nests are globular and often situated on tree stumps. They are about the size of a football.
On one side is a domed entrance that leads to a passage that curves around the left hand side, before going into the central chamber. The inner chamber is well lined and comfortable looking.
The best-known mud nest builders are the Hirundines. Swallows and Martins all over the world labor during the Spring to build their hemispherical nests on the edges of cliffs and under the eaves of houses.
The mud is collected in small pellets and moistened with saliva, before being applied to the wall or existing nest.
Swallow and Martins, in Europe at least, build only in the morning – spending the afternoon feeding. This means that each day’s work gets a chance to dry out and become strong before new mud is added.
If this did not happen the whole thing would collapse under its own weight. Like other mud nesting birds, the nest is normally lined with dried grass and feathers.
Edible Bird Nests
Perhaps the strangest nests of all are those built by the species of Swiftlet in the genus Collocalia.
They nest in caves and build their nests of saliva. To do this they have enlarged salivary glands during the breeding season. To make them even more amazing, these Swiflets often nest in pitch dark caves. They are able to do this by using echolocation, similar to bats.
Quite a few species use saliva in their nests to glue various materials together.
Three species however, Collocalia fuciphaga, C. esculenta and C. maxima, produce nests made almost entirely, or entirely, out of saliva.
These are the nests used by Chinese chefs to prepare bird nest soup – one of the more expensive and tasteless dishes in the world.
The nests are collected from Niah caves – and though collecting is controlled by law – it still results in a huge and unnecessary death of eggs and young birds.
Bird Nests and Plastic
For some species of bird the choice of materials is very hard wired, mud or moss for instance. However other birds are more adaptive in how they build their nests and will make adventitious use of whatever materials around.
In our modern world this material is quite often rubbish, our rubbish that we have failed to dispose of properly. The most common form of rubbish incorporated into nests is by far plastic, but aluminum foil, insulation and even cigarette butts have been recorded.
Observing the trash in bird nests is not always possible, but for species that nest on the ground, or species like storks and raptors that build large nests it is often relatively easy.
Some birds simply incorporate plastic in the same way they would leaves, for other the choice is more deliberate and based on colour and or reflectivity. In these cases, as with the Black Kites in the Italian Alps, it is believed the material is there to show off, the nests with the most plastic belonged to the strongest birds.
In a study published in 2011 it was revealed that Black kites consciously chose white, highly visible plastic with which to decorate their nests.
Plastic being incorporated into bird nests is probably now far more common than most people realize. Another study done in Spring 2020 revealed that plastic debris was to be found in 80 percent of the nests Herring Gulls (Larus argentatus) on an uninhabited island off the coast of Scotland.
The images below come from a bird nest found on the ground in my garden in Cambodia in January 2021, meaning the nest was probably built during the previous breeding season.
Bird Nest FAQs
What other animals make a nest?
Birds are not the only animals to make nests. Fish, mammals, insects and spiders also build nests. Sometimes quite complex ones, for rearing young and for their own general protection.
Well, I hope this page has given you a pretty comprehensive overview of the many different types of bird nests that exist in our world!