Bird nests are, arguably, an example of a tool used by nearly a whole class of animals. Whether you agree or not does not diminish the amazing efforts millions of birds construct every year all around the world.
Birds – far more than any other animal besides man – 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.
Birds are not the only animals to make nests. Fishes, mammals, insects and spiders also build nests. Sometimes quite complex ones, for rearing young and for their own general protection.
For the purposes of this page, 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.
The different types of bird nests range from non-existent to extensive, multi-chambered apartments – which can be fully weatherproof and may last for years or even decades.
Nests come in a wide range of categories, the following types cover most nests you will find. Some of these 12 categories are quite small, others are large containing huge diversity:
- 1 Types Of Bird Nests:
- 1.1 Bowers: Architecture But Not Nests
- 1.2 Birds With No Nest
- 1.3 Simple Birds Nests
- 1.4 Cup Shaped Nests
- 1.5 Enclosed Bird Nests
- 1.6 Hanging Birds Nests and Woven Nests
- 1.7 Holes in the Ground
- 1.8 Holes In Wood
- 1.9 Mound Nests
- 1.10 (Floating) Aquatic Nests
- 1.11 Birds That Build Mud Nests
- 1.12 Edible Bird Nests
- 1.13 Bird Nests and Plastic
Types Of Bird Nests:
- Birds With No Nest
- Floating (Aquatic) Bird Nests
- Edible Bird Nests
- Mound Nests
- Simple Birds Nests
- Cup Shaped Nests
- Enclosed Bird Nests
- Hanging Bird Nests
- Holes in the Ground
- Birds That Build Mud Nests
- Holes in Wood
- Not Nests
- Bird Nests and Plastic
Before building a nest, the pair of birds have to decide on where to build.
This is called ‘nest site selection‘ behaviour. Different species go about this in various ways and in many species both partners work together to decide on the site. Birds in this category include many gulls.
In some species, though, the pair work together and the female takes a definite lead on the proceedings, i.e. Blackbirds, Turdus merula, and surprisingly the Red-necked Phalarope Phaleropus lobatus.
This is surprising because once the site has been chosen, the female lays her eggs and departs – leaving the male to do all the incubation.
In other species such as the Dunnock, Prunella modularis, the female chooses the site and builds the nest. In contrast, with Blue tits, Parus caerulea, European Sparrows, Passer domesticus, and Wrens, Troglodytes troglodytes, it is the male who chooses the site and then tries to attract the female to it.
The male Wren is a bit of a workaholic and builds several nets, normally 4 or 5, but up to 12. The female chooses one of these and the male uses another to roost in.
Just to prove that variety is the spice of life, Scottish Crossbills, Loxia pinicola, show no definite patterns. In some couples the male leads, in others the female.
The second behavioral activity is material collection and building.
These range from ‘sideways throwing’ – a simple single movement to get nesting material to the nest (this is limited to ground nesters only).
‘Sideways building’ is similar, but involves more care in the placing of the material and results in a better constructed birds nest. Sideways throwing and sideways building are exhibited by many ducks, geese, gulls, petrels, pheasants swans and waders.
Physically carrying material to the nest site is the next step up and is carried out by all the remaining nest building birds.
At its simplest, it is shown by penguins carrying a stone in their bills a few metres to the nest site. At its most complex it involves birds searching out for particular substances – such as cobwebs and feathers – to bring to the nest.
Once material is brought to the site, it needs to be incorporated into the nest. For ground nesting species, this can be as simple as just picking it up. For tree nesting species, it usually involves some degree of interweaving the individual items until they form some sort of matrix.
This can be fairly straight forward in the platform nests of pigeons, but reaches great sophistication in the weavers – where material is actually sown together and a considerable degree of manipulatory skill is needed. Whatever the type of nest, watching a bird build one is a fascinating and rewarding experience.
Bowers: Architecture But Not Nests
Firstly, there are structures built by birds which do not really fit into any of the above categories because they are not nests. These are the bowers of the various species of Bowerbird.
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 the 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, which in some areas builds a huge open-fronted roofed hut up to 2.2 m tall and 2 or more metres 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 which 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 leking species in which each male has a personal arena about 1 m across with a pseudo-nest. Mating normally takes place during inspection of the pseudo-nest by the female. Like all leking species, the female builds the true nest later, incubates the eggs and raises the young on her own.
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 colouration 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 which 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.
The master of no nest nesting, however, has to be the Emperor Penguin (Aptenodytes forsteri).
These birds nest in the Antarctic during winter, when the temperature can fall to less than -30 degrees C. They nest well inland and when the female has laid the single egg, she leaves for the coast to feed. Meanwhile the male has immediately taken over care for 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 C, as much as 80 degrees C higher than the surrounding ambient temperature.
Simple Birds Nests
Simple bird nests are constructed of plant material, sticks or stones. They are quite a common type of birds 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 which 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 which 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.
No material is carried to the bird’s nest. Instead, once the site is chosen and the vegetation flattened, the eggs are laid and the female swan builds up the nest around her by dragging material within reach so that eventually it forms a rampart around 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 build in trees and the nests of the Bald Eagle (Haliaeetus leucocephalus) in N. America 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 of the foremost 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 nest and one that most people consider the typical “birds nest”. They are distinguishable because they have a definite inside as well as an outside and the inside is normally lined. They require more effort to make, but convey 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 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, others take 2-3 weeks to complete.
Cup-shaped nests are often built of 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 the bird’s nest, built of twigs and grass cemented together with mud, is larger than the adult bird. Within this rough exterior, a deep cup lined with moss and feathers is made. Crows’ Corvus corone nests often look rough and ready, but inside they are warm and comfortable.
Crows build very well and their nests last for several years. But unlike the closely related but larger Raven Corvus corax, they never reuse a nest.
Other birds, like Kestrels Falco tinnunculus, are happy to use them once the crow has finished with them.
Enclosed Bird Nests
Enclosed bird nests are basically an extended cup nest, where the basic cup has deeper walls and a roof with an entrance hole.
Domed or enclosed nests would seem to offer more protection for the eggs and young than a simple cup. In some cases they obviously do, and they also supply better protection from the elements. Though there is not much scientific evidence to support the theory that they offer better protection from predators.
As with all these categories of bird nests, there is a gradient of complexity and quality among domed nests. The simplest have only a loose roof like those of the Chiffchaff, Phylloscopus collybita, or a separate roof constructed about the dome such as the nest of the Magpie, Pica pica.
Wrens and Dipper build more solid domes.
Many domed bird nests are very intricate and solidly constructed. They may be small and beautiful, such as the nests of the Long-tailed Tit, Aegithalos caudatus, which camouflages the outside with lichens and lines the inside with hundreds of thousands of feathers.
The largest and most spectacular domed nests belong to the Hamerkop, Scopus umbretta.
These birds build a huge dome of over 8,000 sticks which can be 2 m high and nearly 2 m wide. This nest is easily strong enough to withstand a man walking across the top of it. They have a long entrance tunnel and are the avian equivalent of a fortress.
A more unusual example of a domed nest is the nest of the Rufous-breasted Castle Builder, Synallaxis crythrothorax, which creates a dumbbell-shaped nest with a tube connecting both chambers – only one of which is used to rear the 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 birds 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 – often on mass – nests of the Icteridae and Oriolidae.
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 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 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, and those holes in relatively flat ground. A second plane of division is between those birds which dig their own holes and those which make use of other people’s.
Commonly recognised birds which nest in cliff edge holes include House Martins (Delichon urbica), Sand Martins (Riparia riparia) and the widely distributed European Kingfisher (Alcedo atthis).
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 all 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. Not as pleasant as this, Cinclodes sp. and Sharp-tailed Stream Creeper’s (Lochmias nematura) nest in rodent burrows.
In the latter case the burrows are often in the edges of open sewers giving the bird the nickname ‘President of Filth’ in Brazilian shanty towns.
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 bird 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.
Others, like the many hole nesting Parrots and Nuthatches, will modify existing holes to varying degrees. 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 metre from bill-tip to tail-end, which likes to nest between 20-45 metres up the tree trunk.
It can therefore only nest in trees which have a diameter greater than 1-2 metres 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, 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 will not only raise the chicks in great security, but also moult 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. With a captive food supply in the young birds, parasite loads in nest holes build up rapidly. Hornbills never use the same hole twice and the need to escape these pests may have something to do with this.
Other favourite sites for nest holes are cacti, many of which grow as large as small trees, and termite nests.
Each of these provides an interesting example of commensualism.
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’ faeces and any parasites they can find. Obviously, this is good for the Parakeet, but what the termites get out of it, no-on knows for sure.
The second relationship is quite amazing. The Gila Woodpecker (Melanerpes uropygialis) nests in holes which it excavates in the famous Giant Saguaro cactus of N. America.
In the same hole with it, nests the Elf Owl (Micrathene whitneyi). 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 leave the forest where they have lived all year and come 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. Into this sand the females dig a hole about 60 cm (2 ft) deep, and after testing the temperature of the sun with special heat sensors on their tongues (about 33 degrees C is best), they lay their eggs and fill the hole in.
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 (Megapodes = big feet) about 0.5 m (1.5 ft) deep. On top of this he piles all the vegetation he can find, as well as nearby topsoil. The resulting nest mound will 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. Also similar are Brush Turkeys, Alectura lathami, whose 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. No further control is exercised.
(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 which though surrounded by water, have a foundation of vegetation which reaches the ground below. Interestingly the Horned Coot, Fulica cornuta, which breeds on mountain lakes in the Andes where water weed is scarce, build a foundation of stones – nearly to water level – before building the actual nest.
More adventurous are various grebes. Grebes build the 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 which 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 colourful birds which build very basic nests of mud. In the middle of the soda lakes of Africa, you can find both species building up piles of mud and faeces.
These structures are basically a hollow mound with a depression in the centre. 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. They 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 bird’s 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 S. 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 which 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 labour 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 aluminium 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.
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!