Editing Bird nest

{{short description|Place where a bird broods its eggs}}
{{About||animal nests in general|Nest|other uses|Bird's nest (disambiguation){{!}}Bird's nest}}
{{EngvarB|date=July 2022}}
{{Use dmy dates|date=July 2021}}

[[File:Acrocephalus arundinaceus nest (cropped).jpg|thumb|right|Deep cup nest of the [[great reed-warbler]]]]

A '''bird nest''' is the spot in which a bird lays and [[Avian incubation|incubates]] its [[Bird egg|eggs]] and raises its young. Although the term popularly refers to a specific [[structures built by animals|structure]] made by the bird itself—such as the grassy cup nest of the [[American robin]] or [[Eurasian blackbird]], or the elaborately woven hanging nest of the [[Montezuma oropendola]] or the [[village weaver]]—that is too restrictive a definition. For some species, a nest is simply a shallow depression made in sand; for others, it is the knot-hole left by a broken branch, a burrow dug into the ground, a chamber drilled into a tree, an enormous rotting pile of vegetation and earth, a shelf made of dried saliva or a mud dome with an entrance tunnel. The smallest bird nests are those of some [[hummingbird]]s, tiny cups which can be a mere {{convert|2|cm|in|1|abbr=on}} across and {{convert|2|–|3|cm|in|1|abbr=on}} high.<ref name="Campbell386">{{Harvnb|Campbell|Lack|1985|p=386}}</ref> At the other extreme, some nest mounds built by the [[dusky scrubfowl]] measure more than {{convert|11|m|ft|abbr=on}} in diameter and stand nearly {{convert|5|m|ft|abbr=on}} tall.<ref>{{Harvnb|Campbell|Lack|1985|p=345}}</ref> The study of birds' nests is known as ''caliology''.

Not all bird species build nests. Some species lay their eggs directly on the ground or rocky ledges, while [[brood parasites]] lay theirs in the nests of other birds, letting unwitting "foster parents" do the work of rearing the young. Although nests are primarily used for breeding, they may also be reused in the non-breeding season for roosting and some species build special ''dormitory nests'' or ''roost nests'' (or ''winter-nest'') that are used only for roosting.<ref name=skutch>{{Citation|title=The nest as a dormitory|last=Skutch |first=Alexander F|journal=Ibis| volume=103| issue=1 | pages=50–70 | doi=10.1111/j.1474-919X.1961.tb02420.x| year=1960|postscript=.}}</ref> Most birds build a new nest each year, though some refurbish their old nests.<ref>[http://smithsonianscience.org/2015/04/bird-nests-variety-is-key-for-avian-architects smithsonianscience.org 2015-04-20 Bird nests: Variety is Key for the world's avian Architects] {{webarchive|url=https://web.archive.org/web/20170103173244/http://insider.si.edu/2015/04/bird-nests-variety-is-key-for-avian-architects/ |date=3 January 2017 }}</ref> The large '''eyries''' (or '''aeries''') of some eagles are platform nests that have been used and refurbished for several years.

In the majority of nest-building species the female does most or all of the nest construction, in others both partners contribute; sometimes the male builds the nest and the hen lines it.<ref>{{Harvnb|Campbell|Lack|1985|p=387}}</ref><ref>{{cite book |last1=Felix |first1=Jiri |title=Garden and Field Birds |date=1973 |publisher=Octopus books |isbn=0-7064-0236-7 |page=17}}</ref> In some [[Polygyny in animals|polygynous]] species, however, the male does most or all of the nest building. The nest may also form a part of the courtship display such as in [[Ploceidae|weaver birds]]. The ability to choose and maintain good nest sites and build high quality nests may be selected for by females in these species. In some species the young from previous broods may also act as [[Helpers at the nest|helpers]] for the adults.

== Type ==
[[File:Nests.svg|thumb|upright=2]]
Not every bird species builds or uses a nest. Some [[auk]]s, for instance—including [[common murre]], [[thick-billed murre]] and [[razorbill]]—lay their eggs directly onto the narrow rocky ledges they use as breeding sites.<ref name="Handbook">{{Harvnb|Ehrlich|Dobkin|Wheye|Pimm|1994|pp=228–232}}</ref> The eggs of these species are dramatically pointed at one end, so that they roll in a circle when disturbed. This is critical for the survival of the developing eggs, as there are no nests to keep them from rolling off the side of the cliff. Presumably because of the vulnerability of their unprotected eggs, parent birds of these auk species rarely leave them unattended.<ref>{{Harvnb|del Hoyo|1992|p=692}}</ref> Nest location and architecture is strongly influenced by local topography and other abiotic factors.{{sfn|Hogan|2010}}

[[King penguin]]s and [[emperor penguin]]s also do not build nests; instead, they tuck their eggs and chicks between their feet and folds of skin on their lower bellies. They are thus able to move about while incubating, though in practice only the emperor penguin regularly does so. Emperor penguins breed during the harshest months of the [[Antarctic]] winter, and their mobility allows them to form huge huddled masses which help them to withstand the extremely high winds and low temperatures of the season. Without the ability to share body heat (temperatures in the centre of tight groups can be as much as 10C above the ambient air temperature), the penguins would expend far more energy trying to stay warm, and breeding attempts would probably fail.<ref>{{Harvnb|del Hoyo|1992|p=148}}</ref>

Some crevice-nesting species, including [[ashy storm-petrel]], [[pigeon guillemot]], [[Eurasian eagle-owl]] and [[Hume's tawny owl]], lay their eggs in the relative shelter of a crevice in the rocks or a gap between boulders, but provide no additional nest material.<ref>{{Harvnb|Ehrlich|Dobkin|Wheye|Pimm|1994|p=252}}</ref><ref>{{Harvnb|Ehrlich|Dobkin|Wheye|Pimm|1994|p=260}}</ref> [[Potoo]]s lay their single egg directly atop a broken stump, or into a shallow depression on a branch—typically where an upward-pointing branch died and fell off, leaving a small scar or knot-hole.<ref>{{Harvnb|Cohn-Haft|1999|p=295}}</ref> [[Brood parasite]]s, such as the [[New World]] [[cowbird]]s, the [[honeyguide]]s, and many of the [[Old World]] and [[Australasia]]n [[cuckoo]]s, lay their eggs in the active nests of other species.<ref>{{Harvnb|Jaramillo|2001|p=548}}</ref><ref>{{Harvnb|Short|Horne|2002b|p=282}}</ref><ref>{{Citation |last1=JE |first1=Simon |last2=Pacheco |year=2005 |title=On the standardization of nest descriptions of neotropical birds |journal=Revista Brasileira de Ornitologia |volume=13 |issue=2 |pages=143–154 |url=http://www.faunaparaguay.com/Sim13.pdf |url-status=live |archive-url=https://web.archive.org/web/20080720071436/http://www.faunaparaguay.com/Sim13.pdf |archive-date=20 July 2008 }}</ref>

{{anchor|Scrapes}}

=== Scrape ===
<!-- [[Scrape nest]] redirects to this heading. -->
[[File:Gniazdo sieweczki RB.JPG|thumb|alt=Three eggs, bluish with black speckling, sit atop a layer of white mollusc shells pieces, surrounded by sandy ground and small bits of bluish stone.|Some nest linings, such as the shell fragments in this ''[[Charadrius]]'' [[plover]] scrape, may help to prevent the eggs from sinking into muddy or sandy soil.]]

The simplest nest construction is the ''scrape'', which is merely a shallow depression in soil or vegetation.<ref>{{Harvnb|Campbell|Lack|1985|p=390}}</ref> This nest type, which typically has a rim deep enough to keep the eggs from rolling away, is sometimes lined with bits of vegetation, small [[rock (geology)|stone]]s, [[seashell|shell]] fragments or [[feather]]s.<ref>{{Harvnb|Ehrlich|Dobkin|Wheye|Pimm|1994|p=xxii}}</ref> These materials may help to camouflage the eggs or may provide some level of insulation; they may also help to keep the eggs in place, and prevent them from sinking into muddy or sandy soil if the nest is accidentally flooded.<ref>{{Harvnb|Ehrlich|Dobkin|Wheye|Pimm|1994|p=441}}</ref> Ostriches, most [[tinamou]]s, many ducks, most [[shorebird]]s, most [[tern]]s, some [[falcon]]s, [[pheasant]]s, [[quail]], [[partridge]]s, [[bustard]]s and [[sandgrouse]] are among the species that build scrape nests.

Eggs and young in scrape nests, and the adults that brood them, are more exposed to [[predator]]s and the [[weather|elements]] than those in more sheltered nests; they are on the ground and typically in the open, with little to hide them. The eggs of most ground-nesting birds (including those that use scrape nests) are cryptically coloured to help camouflage them when the adult is not covering them; the actual colour generally corresponds to the substrate on which they are laid.<ref>{{Harvnb|Campbell|Lack|1985|p=174}}</ref> Brooding adults also tend to be well camouflaged, and may be difficult to flush from the nest. Most ground-nesting species have well-developed [[distraction display]]s, which are used to draw (or drive) potential predators from the area around the nest.<ref>{{Harvnb|Campbell|Lack|1985|p=145}}</ref> Most species with this type of nest have [[precocial]] young, which quickly leave the nest upon hatching.<ref>{{Citation |title=The Nature Handbook: A Guide to Observing the Great Outdoors |first=Ernest Herbert |last=Williams |year=2005 |publisher=Oxford University Press, US |page=115 |isbn=978-0-19-517194-5}}</ref>

[[File:Peregrine falcon nest-scraping, Derby Cathedral.webm|thumb|Female [[peregrine falcon]] nest-scraping on artificial ledge on [[Derby Cathedral]]. Both sexes contribute to the creation of a bare, shallow depression in soil or gravel.]]

In cool climates (such as in the high [[Arctic]] or at high elevations), the depth of a scrape nest can be critical to both the survival of developing eggs and the fitness of the parent bird incubating them. The scrape must be deep enough that eggs are protected from the [[convective]] cooling caused by cold winds, but shallow enough that they and the parent bird are not too exposed to the cooling influences of ground temperatures, particularly where the [[permafrost]] layer rises to mere centimeters below the nest. Studies have shown that an egg within a scrape nest loses heat 9% more slowly than an egg placed on the ground beside the nest; in such a nest lined with natural vegetation, heat loss is reduced by an additional 25%.<ref name=Reid>{{Citation |doi=10.1046/j.1365-2435.2002.00632.x |journal=Functional Ecology |first1=J. M. |last1=Reid |first2=W. |last2=Cresswell |first3=S. |last3=Holt |first4=R. J. |last4=Mellanby |first5=D. P. |last5=Whitby |first6=G. D |last6=Ruxton |volume=16 |issue=3 |pages=305–316 |title=Nest scrape design and clutch heat loss in the Pectoral Sandpiper (''Calidris melanotos'') |year=2002 |postscript=.}}</ref> The insulating factor of nest lining is apparently so critical to egg survival that some species, including [[Kentish plover]]s, will restore experimentally altered levels of insulation to their pre-adjustment levels (adding or subtracting material as necessary) within 24 hours.<ref>{{Citation |doi=10.1163/156853902320262844 |journal=Behaviour |title=Do Kentish plovers regulate the amount of their nest material? An Experimental Test |first1=István |last1=Szentirmai |first2=Tamás |last2=Székely |volume=139 |issue=6 |pages=847–859 |year=2002 |jstor=4535956 |postscript=.}}</ref>

[[File:Pluvialis dominica eggs and nest.jpg|thumb|left|alt=Four beige eggs, heavily speckled with black, sit in a shallow depression lined with pale greenish-white lichen.|Other nest linings, like the [[lichen]] in this [[American golden-plover]] scrape, may provide some level of insulation for the eggs, or may help to camouflage them.]]
In warm climates, such as [[desert]]s and [[Salt pan (geology)|salt flat]]s, heat rather than cold can kill the developing embryos. In such places, scrapes are shallower and tend to be lined with non-vegetative material (including shells, feathers, sticks and soil),{{sfn|Grant |1982|p=11}} which allows convective cooling to occur as air moves over the eggs. Some species, such as the [[lesser nighthawk]] and the [[red-tailed tropicbird]], help reduce the nest's temperature by placing it in partial or full shade.{{sfn|Grant |1982|p=60}}<ref>{{Citation |doi=10.2307/1365438 |title=Temperature Regulation in the Red-tailed Tropicbird and the Red-footed Booby |first1=Thomas R. |last1=Howell |first2=George A |last2=Bartholomew |journal=The Condor |volume=64 |issue=1 |pages=6–18 |year=1962 |postscript=.|jstor=1365438 }}</ref> Others, including some shorebirds, cast shade with their bodies as they stand over their eggs. Some shorebirds also soak their breast feathers with water and then sit on the eggs, providing moisture to enable [[evaporative cooling]].{{sfn|Grant |1982|p=61}} Parent birds keep from overheating themselves by [[gular panting]] while they are incubating, frequently exchanging incubation duties, and standing in water when they are not incubating.{{sfn|Grant |1982|p=62}}

The technique used to construct a scrape nest varies slightly depending on the species. Beach-nesting terns, for instance, fashion their nests by rocking their bodies on the [[sand]] in the place they have chosen to site their nest,<ref>{{Harvnb|del Hoyo|Elliott|Sargatal|1996|p=637}}</ref> while [[Skimmer (bird)|skimmers]] build their scrapes with their feet, kicking sand backwards while resting on their bellies and turning slowly in circles.<ref>{{Harvnb|del Hoyo|Elliott|Sargatal|1996|p=673}}</ref> The ostrich also scratches out its scrape with its feet, though it stands while doing so.<ref>{{Harvnb|del Hoyo|1992|p=80}}</ref> Many tinamous lay their eggs on a shallow mat of dead [[leaves]] they have collected and placed under [[shrub|bush]]es or between the [[root]] buttresses of trees,<ref>{{Harvnb|del Hoyo|1992|p=119}}</ref> and [[kagu]]s lay theirs on a pile of dead leaves against a log, tree trunk or vegetation.<ref>{{Harvnb|del Hoyo|Elliott|Sargatal|1996|p=222}}</ref> [[Marbled godwit]]s stomp a grassy area flat with their feet, then lay their eggs, while other grass-nesting waders bend vegetation over their nests so as to avoid detection from above.<ref>{{Harvnb|del Hoyo|Elliott|Sargatal|1996|p=473}}</ref> Many female ducks, particularly in the northern [[latitude]]s, line their shallow scrape nests with [[down feather]]s plucked from their own breasts, as well as with small amounts of vegetation.<ref>{{Harvnb|del Hoyo|1992|p=558}}</ref> Among scrape-nesting birds, the [[three-banded courser]] and [[Egyptian plover]] are unique in their habit of partially burying their eggs in the sand of their scrapes.<ref>{{Harvnb|del Hoyo|Elliott|Sargatal|1996|p=371}}</ref>

=== Mound ===
[[File:Malleefowl mound.jpg|alt=A large pile of bare earth stands amidst pale tree trunks, bleached grass and fallen sticks.|The huge mound nest of the [[malleefowl]] acts like a compost heap, warming and incubating the eggs as it rots around them.|thumb|right]]

Burying eggs as a form of incubation reaches its zenith with the [[Australasia]]n [[megapode]]s. Several megapode species construct enormous ''mound'' nests made of soil, branches, sticks, twigs and leaves, and lay their eggs within the rotting mass. The heat generated by these mounds, which are in effect giant [[compost heap]]s, warms and incubates the eggs.<ref name="Campbell386"/> The nest heat results from the respiration of thermophilic fungi and other [[microorganism]]s.<ref name="HBW2-287"/> The size of some of these mounds can be truly staggering; several of the largest—which contain more than {{convert|100|m3|yd3}} of material, and probably weigh more than 50 tons (45,000&nbsp;kg)<ref name="HBW2-287">{{Harvnb|Elliott|1994|p=287}}</ref>—were initially thought to be [[Indigenous Australians|Aboriginal]] middens.{{sfn|Hansell|2000|p=9}}

In most mound-building species, males do most or all of the nest construction and maintenance. Using his strong legs and feet, the male scrapes together material from the area around his chosen nest site, gradually building a [[cone (geometry)|conical]] or bell-shaped pile. This process can take five to seven hours a day for more than a month. While mounds are typically reused for multiple breeding seasons, new material must be added each year to generate the appropriate amount of heat. A female will begin to lay eggs in the nest only when the mound's temperature has reached an optimal level.<ref name="HBW2-288">{{Harvnb|Elliott|1994|p=288}}</ref>

[[File:Slimbridge.chilean.flamingo.arp.jpg|thumb|left|upright|alt=Two long-legged, long-necked pink birds stand atop cylindrical piles of mud, with water in the background.|The mound nests of flamingos, like these [[Chilean flamingo]]s, help to protect their eggs from fluctuating water levels.]]

Both the temperature and the moisture content of the mound are critical to the survival and development of the eggs, so both are carefully regulated for the entire length of the breeding season (which may last for as long as eight months), principally by the male.<ref name="HBW2-287"/> [[Ornithologist]]s believe that megapodes may use sensitive areas in their mouths to assess mound temperatures; each day during the breeding season, the male digs a pit into his mound and sticks his head in.<ref>{{Harvnb|Elliott|1994|p=280}}</ref> If the mound's core temperature is a bit low, he adds fresh moist material to the mound, and stirs it in; if it is too high, he opens the top of the mound to allow some of the excess heat to escape. This regular monitoring also keeps the mound's material from becoming compacted, which would inhibit oxygen diffusion to the eggs and make it more difficult for the chicks to emerge after hatching.<ref name="HBW2-288"/> The [[malleefowl]], which lives in more open forest than do other megapodes, uses the sun to help warm its nest as well—opening the mound at midday during the cool spring and autumn months to expose the plentiful sand incorporated into the nest to the sun's warming rays, then using that warm sand to insulate the eggs during the cold nights. During hot summer months, the malleefowl opens its nest mound only in the cool early morning hours, allowing excess heat to escape before recovering the mound completely.<ref>{{Harvnb|Elliott|1994|p=289}}</ref> One recent study showed that the sex ratio of [[Australian brushturkey]] hatchlings correlated strongly with mound temperatures; females hatched from eggs incubated at higher mean temperatures.<ref>{{Citation |last=Göth |first=Anne |title=Incubation temperatures and sex ratios in Australian brush-turkey (''Alectura lathami'') mounds |journal=Austral Ecology |year=2007 |volume=32 |issue=4 |pages=278–285 |doi=10.1111/j.1442-9993.2007.01709.x|bibcode=2007AusEc..32..378G }}</ref>

[[Flamingo]]s make a different type of mound nest. Using their [[beak]]s to pull material towards them,<ref name = "delHoyo516">{{Harvnb|del Hoyo|1992|p=516}}</ref> they fashion a cone-shaped pile of mud between {{convert|15|–|46|cm|in|round=0.5|abbr=on}} tall, with a small depression in the top to house their single egg.<ref>{{Harvnb|Seng|2001|p=188}}</ref> The height of the nest varies with the substrate upon which it is built; those on [[clay]] sites are taller on average than those on dry or sandy sites.<ref name = "delHoyo516"/> The height of the nest and the circular, often water-filled trench which surrounds it (the result of the removal of material for the nest) help to protect the egg from fluctuating water levels and excessive heat at ground level. In East Africa, for example, temperatures at the top of the nest mound average some {{convert|20|°C-change|abbr=on}} cooler than those of the surrounding ground.<ref name = "delHoyo516"/>

The base of the [[horned coot]]'s enormous nest is a mound built of stones, gathered one at a time by the pair, using their beaks. These stones, which may weigh as much as 450 g (about a pound) each, are dropped into the shallow water of a lake, making a [[Cone (geometry)|cone]]-shaped pile which can measure as much as {{convert|4|m2|ft2|abbr=on}} at the bottom and {{convert|1|m2|ft2|abbr=on}} at the top, and {{convert|0.6|m|ft|abbr=on}} in height. The total combined weight of the mound's stones may approach 1.5 tons (1,400&nbsp;kg). Once the mound has been completed, a sizable platform of aquatic vegetation is constructed on top. The entire structure is typically reused for many years.<ref>{{Citation|title=Rails |first1=Barry |last1=Taylor |first2=Ber |last2=van Perlo |year=1998 |publisher=Pica Press |location=Sussex |isbn=978-1-873403-59-4 |page=557}}</ref>

=== Burrow ===
<!-- [[Burrow nest]] redirects to this heading. -->
[[File:Riparia riparia-Oeverzwaluw.jpg|thumb|Like most burrow-nesting species, [[sand martin]]s dig a horizontal tunnel into a vertical dirt cliff.]]

Soil plays a different role in the ''burrow'' nest; here, the eggs and young—and in most cases the incubating parent bird—are sheltered under the earth. Most burrow-nesting birds excavate their own burrows, but some use those excavated by other species and are known as secondary nesters; [[burrowing owl]]s, for example, sometimes use the burrows of [[prairie dog]]s, [[ground squirrel]]s, [[badger]]s or [[tortoise]]s,<ref>{{Harvnb|Behrstock|2001|p=344}}</ref> China's endemic [[white-browed tit]]s use the holes of ground-nesting rodents<ref>{{Harvnb|Harrap|Quinn|1996|p=21}}</ref> and [[common kingfisher]]s occasionally nest in rabbit burrows.<ref name = "HBW6-169">{{Harvnb|Woodall|2001|p=169}}</ref> Burrow nests are particularly common among seabirds at high latitudes, as they provide protection against both cold temperatures and predators.<ref name=LowTemp>{{Citation |title=Animal Life at Low Temperature |first=John |last=Davenport |journal=Journal of Animal Ecology |year=1992 |volume=61 |issue=3 |publisher=Springer |isbn=978-0-412-40350-7 |pages=[https://archive.org/details/animallifeatlowt0000dave/page/81 81–82] |doi=10.2307/5635 |jstor=5635 |bibcode=1992JAnEc..61..798B |url=https://archive.org/details/animallifeatlowt0000dave/page/81 }}</ref> [[Puffin]]s, [[shearwater]]s, some megapodes, [[motmot]]s, [[tody|todies]], most [[kingfisher]]s, the [[crab plover]], [[Geositta|miner]]s and [[Sclerurus|leaftosser]]s are among the species which use burrow nests.

Most burrow nesting species dig a horizontal tunnel into a vertical (or nearly vertical) dirt cliff, with a chamber at the tunnel's end to house the eggs.<ref>{{Harvnb|Ehrlich|Dobkin|Wheye|Pimm|1994|p=xxiii}}</ref> The length of the tunnel varies depending on the substrate and the species; [[sand martins]] make relatively short tunnels ranging from {{convert|50|–|90|cm|in|abbr=on}},<ref>{{Harvnb|Ehrlich|Dobkin|Wheye|Pimm|1994|p=345}}</ref> for example, while those of the [[burrowing parakeet]] can extend for more than three meters (nearly 10&nbsp;ft).<ref>{{Harvnb|Juniper|Parr|2003|p=24}}</ref> Some species, including the ground-nesting [[puffbird]]s, prefer flat or gently sloping land, digging their entrance tunnels into the ground at an angle.<ref>{{Harvnb|Rasmussen|Collar|2002|p=119}}</ref> In a more extreme example, the [[D'Arnaud's barbet]] digs a vertical tunnel shaft more than a meter (39&nbsp;in) deep, with its nest chamber excavated off to the side at some height above the shaft's bottom; this arrangement helps to keep the nest from being flooded during heavy rain.<ref>{{Harvnb|Short|Horne|2002a|p=162}}</ref> [[Buff-breasted paradise-kingfisher]]s dig their nests into the compacted mud of active termite mounds, either on the ground or in trees.<ref name="HBW6-169"/> Specific soil types may favour certain species and it is speculated that several species of bee-eater favor [[loess]] soils which are easy to penetrate.<ref>{{cite journal| title= Loess and bee-eaters I: Ground properties affecting the nesting of European bee-eaters (''Merops apiaster'' L.1758) in loess deposits| journal= Quaternary International| volume= 296| pages=220–226| year=2013|author1= Smalley, Ian| author2=O'Hara-Dhand, Ken|author3= McLaren, Sue|author4= Svircev, Zorica|author5=Nugent, Hugh|doi=10.1016/j.quaint.2012.09.005| bibcode= 2013QuInt.296..220S| hdl= 2381/31362| url= https://figshare.com/articles/journal_contribution/10137392| hdl-access= free}}</ref><ref>{{cite journal |last=Heneberg |first=P. | title=Soil penetrability as a key factor affecting nesting of burrowing birds| journal=Ecological Research| volume=24 |issue=2 |year=2009| pages= 453–459| doi=10.1007/s11284-008-0520-2|bibcode=2009EcoR...24..453H |s2cid=22934726}}</ref>

[[File:Merops apiaster burrows.jpg|thumb|left|Increased vulnerability to predators may have led some burrow-nesting species, like the [[European bee-eater]], to become colonial breeders.]]

Birds use a combination of their beaks and feet to excavate burrow nests. The tunnel is started with the beak; the bird either probes at the ground to create a depression, or flies toward its chosen nest site on a cliff wall and hits it with its bill. The latter method is not without its dangers; there are reports of kingfishers being fatally injured in such attempts.<ref name="HBW6-169"/> Some birds remove tunnel material with their bills, while others use their bodies or shovel the dirt out with one or both feet. Female paradise-kingfishers are known to use their long tails to clear the loose soil.<ref name="HBW6-169"/>

Some [[crepuscular]] [[petrel]]s and [[prion (bird)|prion]]s are able to identify their own burrows within dense colonies by smell.<ref>{{Citation |last1=Bonadonna |first1=Francesco |last2=Cunningham |first2=Gregory B. |last3=Jouventin |first3=Pierre |last4=Hesters |first4=Florence |last5=Nevitt |first5=Gabrielle A. |title=Evidence for nest-odour recognition in two species of diving petrel |journal=The Journal of Experimental Biology |year=2003 |volume=206 |pages=3719–3722 |doi=10.1242/jeb.00610 |pmid=12966063 |issue=Pt 20 |postscript=.|doi-access=free |bibcode=2003JExpB.206.3719B }}</ref> Sand martins learn the location of their nest within a colony, and will accept any chick put into that nest until right before the young fledge.<ref>{{Citation |title=Perspectives on Animal Behavior |first1=Judith |last1=Goodenough |first2=Betty |last2=McGuire |first3=Robert A. |last3=Wallace |first4=Elizabeth |last4=Jacob |location=Hoboken, NJ |publisher=John Wiley and Sons |page=430 |isbn=978-0-470-04517-6|date=22 September 2009 }}</ref>

Not all burrow-nesting species incubate their young directly. Some megapode species, such as the [[maleo]], bury their eggs in sandy pits dug where sunlight, subterranean volcanic activity, or decaying tree roots will warm the eggs.<ref name="Campbell386"/><ref name="HBW2-287"/> The crab plover also uses a burrow nest, the warmth of which allows it to leave the eggs unattended for as long as 58 hours.<ref>{{Citation|last1=De Marchi|first1=G.|last2=Chiozzi |first2=G. |last3=Fasola |first3=M. |year=2008|title=Solar incubation cuts down parental care in a burrow nesting tropical shorebird, the crab plover ''Dromas ardeola''|journal=Journal of Avian Biology|volume=39|issue=5|pages=484–486|doi=10.1111/j.0908-8857.2008.04523.x}}</ref>

Predation levels on some burrow-nesting species can be quite high; on [[Alaska]]'s Wooded Islands, for example, [[North American river otter|river otter]]s munched their way through some 23 percent of the island's [[fork-tailed storm-petrel]] population during a single breeding season in 1977.<ref>{{Citation |title=The Breeding Biology of the Fork-tailed Storm-Petrel (''Oceandroma furcata'') |last1=Boersma |first1=P. Dee |first2=Nathaniel T. |last2=Wheelwright |first3=Mary K. |last3=Nerini |first4=Eugenia Stevens |last4=Wheelwright |journal=Auk |volume=97 |pages=268–282 |date=April 1980 |url=http://sora.unm.edu/sites/default/files/journals/auk/v097n02/p0268-p0282.pdf |issue=2 |url-status=live |archive-url=https://web.archive.org/web/20140821072357/http://sora.unm.edu/sites/default/files/journals/auk/v097n02/p0268-p0282.pdf |archive-date=21 August 2014 }}</ref> There is some evidence that increased vulnerability may lead some burrow-nesting species to form colonies, or to nest closer to rival pairs in areas of high predation than they might otherwise do.<ref>{{Harvnb|Ehrlich|Dobkin|Wheye|Pimm|1994|p=17}}</ref>

=== Cavity ===
[[File:Forpus xanthopterygius -tree hole -Brazil-8.jpg|thumb|"Secondary cavity nesters", like this [[cobalt-rumped parrotlet]], use natural cavities or holes excavated by other species.]]

The ''cavity'' nest is a chamber, typically in living or dead wood, but sometimes in the trunks of [[tree fern]]s<ref name="HBW6-94">{{Harvnb|Collar|2001|p=94}}</ref> or large [[cactus|cacti]], including [[Carnegiea|saguaro]].<ref name="HBW6-94"/><ref name = "WP"/> In tropical areas, cavities are sometimes excavated in arboreal insect nests.<ref>{{Citation |last=Brightsmith |first=Donald J. |title=Use of Arboreal Termitaria by Nesting Peruvian Amazon |journal=Condor |year=2000 |volume=102 |issue=3 |pages=529–538 |url=http://sora.unm.edu/sites/default/files/journals/condor/v102n03/p0529-p0538.pdf |doi=10.1650/0010-5422(2000)102[0529:UOATBN]2.0.CO;2 |s2cid=52541280 |url-status=live |archive-url=https://web.archive.org/web/20160128025203/http://sora.unm.edu/sites/default/files/journals/condor/v102n03/p0529-p0538.pdf |archive-date=28 January 2016 }}</ref><ref name = "HBW6-96">{{Harvnb|Collar|2001|p=96}}</ref> A relatively small number of species, including [[woodpecker]]s, [[trogon]]s, some [[nuthatch]]es and many [[Ramphastides|barbets]], can excavate their own cavities. Far more species—including parrots, [[Paridae|tit]]s, [[bluebird]]s, most [[hornbill]]s, some kingfishers, some [[true owl|owl]]s, some ducks and some flycatchers—use natural cavities, or those abandoned by species able to excavate them; they also sometimes usurp cavity nests from their excavating owners. Those species that excavate their own cavities are known as "primary cavity nesters", while those that use natural cavities or those excavated by other species are called "secondary cavity nesters". Both primary and secondary cavity nesters can be enticed to use [[nest box]]es (also known as bird houses); these mimic natural cavities, and can be critical to the survival of species in areas where natural cavities are lacking.<ref>{{Citation |journal=BirdScope |date=Winter 2005 |title=Nest Boxes: More than Just Birdhouses |last=Phillips |first=Tina |volume=19 |issue=1 |url=http://www.birds.cornell.edu/Publications/Birdscope/Winter2005/nest_boxes.html |url-status=live |archive-url=https://web.archive.org/web/20070719060059/http://www.birds.cornell.edu/Publications/Birdscope/winter2005/nest_boxes.html |archive-date=19 July 2007 }}</ref>

Woodpeckers use their chisel-like bills to excavate their cavity nests, a process which takes, on average, about two weeks.<ref name = "WP">{{Harvnb|Reed|2001|pp=380–1}}</ref> Cavities are normally excavated on the downward-facing side of a branch, presumably to make it more difficult for predators to access the nest, and to reduce the chance that rain floods the nest.<ref name = "Conner">{{Harvnb|Conner|1975|p=373}}</ref> There is also some evidence that fungal rot may make the wood on the underside of leaning trunks and branches easier to excavate.<ref name = "Conner"/> Most woodpeckers use a cavity for only a single year. The endangered [[red-cockaded woodpecker]] is an exception; it takes far longer—up to two years—to excavate its nest cavity, and may reuse it for more than two decades.<ref name = "WP"/> The typical woodpecker nest has a short horizontal tunnel which leads to a vertical chamber within the trunk. The size and shape of the chamber depends on species, and the entrance hole is typically only as large as is needed to allow access for the adult birds. While wood chips are removed during the excavation process, most species line the floor of the cavity with a fresh bed of them before laying their eggs.

[[File:BlackWoods.jpg|thumb|left|Only a relatively small number of species, including the woodpeckers, are capable of excavating their own cavity nests.]]

Trogons excavate their nests by chewing cavities into very soft dead wood; some species make completely enclosed chambers (accessed by upward-slanting entrance tunnels), while others—like the extravagantly plumed [[resplendent quetzal]]—construct more open niches.<ref name="HBW6-96"/> In most trogon species, both sexes help with nest construction. The process may take several months, and a single pair may start several excavations before finding a tree or stump with wood of the right consistency.

Species which use natural cavities or old woodpecker nests sometimes line the cavity with soft material such as grass, moss, lichen, feathers or fur. Though a number of studies have attempted to determine whether secondary cavity nesters preferentially choose cavities with entrance holes facing certain directions, the results remain inconclusive.<ref name="Rendell">{{citation |last1=Rendell |first1=Wallace B. |last2=Robertson |first2=Raleigh J. |title=Cavity Entry Orientation and Nest-site Use by Secondary Hole-nesting Birds |journal=Journal of Field Ornithology |year=1994 |volume=65 |pages=27–35 |issue=1 |url=http://sora.unm.edu/sites/default/files/journals/jfo/v065n01/p0027-p0035.pdf |url-status=live |archive-url=https://web.archive.org/web/20160304210619/http://sora.unm.edu/sites/default/files/journals/jfo/v065n01/p0027-p0035.pdf |archive-date=4 March 2016 }}</ref> While some species appear to preferentially choose holes with certain orientations, studies (to date) have not shown consistent differences in fledging rates between nests oriented in different directions.<ref name = "Rendell"/>

Cavity-dwelling species have to contend with the danger of predators accessing their nest, catching them and their young inside and unable to get out.<ref>{{Citation |title=New Generation Guide to the Birds of Britain and Europe |first1=Christopher M |last1=Perrins |first3=Norman |last3=Arlott |first2=David |last2=Attenborough |year=1987 |publisher=University of Texas Press |page=230 |location=Austin, TX |isbn=978-0-292-75532-1}}</ref> They have a variety of methods for decreasing the likelihood of this happening. Red-cockaded woodpeckers peel bark around the entrance, and drill wells above and below the hole; since they nest in live trees, the resulting flow of resin forms a barrier that prevents snakes from reaching the nests.<ref>{{harvnb|Rudolph|Kyle|Conner|1990}}</ref> [[Red-breasted nuthatch]]es smear sap around the entrance holes to their nests, while [[white-breasted nuthatch]]es rub foul-smelling insects around theirs.<ref>{{Harvnb|Reed|2001|p=437}}</ref> [[Eurasian nuthatch]]es wall up part of their entrance holes with mud, decreasing the size and sometimes extending the tunnel part of the chamber. Most female hornbills seal themselves into their cavity nests, using a combination of mud (in some species brought by their mates), food remains and their own droppings to reduce the entrance hole to a narrow slit.<ref>{{Harvnb|Kemp|2001|p=469}}</ref>

A few birds are known to use the nests of insects within which they create a cavity in which they lay their eggs. These include the [[rufous woodpecker]] which nests in the arboreal nests of ''[[Crematogaster]]'' ants and the [[collared kingfisher]] which uses termite nests.<ref>{{Cite journal|last=Moreau|first=R. E.|date=1936|title=XXVI.-Bird-Insect Nesting Associations|journal=Ibis|language=en|volume=78|issue=3|pages=460–471|doi=10.1111/j.1474-919X.1936.tb03399.x}}</ref>

In December 2024, scientists reported that birds that build their nests in cavities are more than six times more likely to incorporate snakeskin into their nests than those which build cup-shaped nests. The same study found that the snake skin helped deter predators from eggs during their incubation period.<ref>{{Cite news |last=Golembiewski |first=Kate |date=2025-01-25 |title=Snakeskin Isn’t Just a Fashion Statement for Birds |url=https://www.nytimes.com/2025/01/25/science/snakeskin-birds-nests.html |access-date=2025-01-30 |work=The New York Times |language=en-US |issn=0362-4331}}</ref>

=== Cup ===
<!-- [[Cup nest]] redirects to this heading. -->
[[File:Heliothryx barroti on nest.jpg|thumb|Like many small birds, the [[purple-crowned fairy]] uses considerable amounts of [[spider silk]] in its cup nest.]]
The ''cup'' nest is smoothly hemispherical inside, with a deep depression to house the eggs. Most are made of pliable materials—including grasses—though a small number are made of [[mud]] or [[saliva]].{{sfn|Hansell |2000|p=[https://archive.org/details/birdnestsconstru0000hans/page/280 280]}} Many [[passerine]]s and a few non-passerines, including some [[hummingbird]]s and some swifts, build this type of nest.

[[File:Turdus merula Nesting.jpg|thumb|left|Cup nest of a [[common blackbird]]]]
Small bird species in more than 20 passerine families, and a few non-passerines—including most hummingbirds, kinglets and crests in the genus ''[[Regulus (bird)|Regulus]]'', some [[tyrant flycatcher]]s and several [[New World warbler]]s—use considerable amounts of [[spider silk]] in the construction of their nests.<ref>{{Harvnb|Ehrlich|Dobkin|Wheye|Pimm|1994|p=445}}</ref><ref name=Erickson>{{Citation |last=Erickson |first=Laura |title=The Wonders of Spider Silk |journal=BirdScope |date=Spring 2008 |volume=22 |issue=2 |pages=7}}</ref> The lightweight material is strong and extremely flexible, allowing the nest to mold to the adult during incubation (reducing heat loss), then to stretch to accommodate the growing nestlings; as it is sticky, it also helps to bind the nest to the branch or [[leaf]] to which it is attached.<ref name=Erickson/>

{{multiple image|total_width=350|footer=Museum specimen of a [[blue-grey gnatcatcher]] cup nest, made with lichens, hair, and spiderwebs.|image1=Blue gray gnatcatcher nest, side 2016-01-07-17.24 (24438660975).jpg|width1=5360|height1=3840|image2=Blue gray gnatcatcher nest, top 2016-01-07-17.39 (24330333612).jpg|width2=5248|height2=3904}}
[[File:Bird nest on a tree.jpg|thumb|278x278px|A bed nest on a tree]]
Many swifts and some hummingbirds{{sfn|Gould |Gould |2007|p=200}} use thick, quick-drying saliva to anchor their nests. The [[chimney swift]] starts by dabbing two globs of saliva onto the wall of a chimney or tree trunk. In flight, it breaks a small twig from a tree and presses it into the saliva, angling the twig downwards so that the central part of the nest is the lowest. It continues adding globs of saliva and twigs until it has made a crescent-shaped cup.{{sfn|Gould |Gould |2007|p=196}}

Cup-shaped nest insulation has been found to be related to nest mass,<ref name="Kern 1984 455–466">{{Citation|last=Kern|first=M|title=Racial differences in nests of white-crowned sparrows|journal=Condor|year=1984|volume=86|issue=4|pages=455–466|doi=10.2307/1366826|jstor=1366826}}</ref><ref name="Heenan 2011">{{Citation|last1=Heenan|first1=Caragh|last2=Seymour |first2=R.|title=Structural support, not insulation, is the primary driver for avian cup-shaped nest design|journal=[[Proceedings of the Royal Society B]]|year=2011|doi=10.1098/rspb.2010.2798|pmid=21325330|volume=278|issue=1720|pages=2924–2929|pmc=3151712}}</ref> nest wall thickness,<ref name="Heenan 2011"/><ref name="Skowron 1980 816–824">{{Citation|last1=Skowron|first1=C|last2=Kern|first2=M.|title=The insulation in nests of selected North-American songbirds|journal=Auk|year=1980|volume=97|issue=4|pages=816–824|doi=10.1093/auk/97.4.816}}</ref><ref>{{Citation|last1=Whittow |first1=F.N.|last2=Berger |first2=A.J.|title=Heat loss from the nest of the Hawaiian honeycreeper, 'Amakihi'|journal=Wilson Bulletin|year=1977|volume=89|pages=480–483}}</ref> nest depth,<ref name="Kern 1984 455–466"/><ref name="Heenan 2011"/> nest weave density/porosity,<ref name="Kern 1984 455–466"/><ref name="Skowron 1980 816–824"/><ref name="Kern 1984 443–454">{{Citation|last1=Kern|first1=M. D.|last2=Van Riper|first2=C.|title=Altitudinal variations in nests of the Hawaiian honeycreeper Hemignathus virens virens|journal=Condor|year=1984|volume=86|issue=4|pages=443–454|doi=10.2307/1366825|jstor=1366825}}</ref> surface area,<ref name="Heenan 2011"/> height above ground<ref name="Kern 1984 455–466"/> and elevation above sea level.<ref name="Kern 1984 443–454"/>

[[File:Процесс строительства гнезда.WebM|thumb|A pair of [[long-tailed tit]]s in the process of building a nest]]
More recently, nest insulation has been found to be related to the mass of the incubating parent.<ref name="Heenan 2011"/> This is known as an [[allometric]] relationship. Nest walls are constructed with an adequate quantity of nesting material so that the nest will be capable of supporting the contents of the nest. Nest thickness, nest mass and nest dimensions therefore correlate with the mass of the adult bird.<ref name="Heenan 2011"/> The flow-on consequence of this is that nest insulation is also related to parent mass.<ref name="Heenan 2011"/>

[[File:Nest 013.jpg|thumb|Hanging bird nest]]
=== Saucer or plate ===

The ''saucer'' or ''plate'' nest, though superficially similar to a cup nest, has at most only a shallow depression to house the eggs.

=== Platform ===
[[File:Osprey landing in the nest at Camp Echockotee.JPG|thumb|left|Many raptors, like the [[osprey]], use the same huge platform nest for years, adding new material each season.]]
[[File:Grebecoveringeggs4502.jpg|thumb|Some waterbirds, including the [[grebe]]s, build floating platform nests.]]

The ''platform'' nest is a large structure, often many times the size of the (typically large) bird which has built it. Depending on the species, these nests can be on the ground or elevated.<ref>{{Citation |title=Zoology: An Inside View of Animals |first=Kenneth |last=Hyde |year=2004 |publisher=Kendall Hunt |location=Dubuque, IA |isbn=978-0-7575-0997-1 |page=474}}</ref>
In the case of raptor nests, or ''eyries'' (also spelled ''aerie''), these are often used for many years, with new material added each breeding season. In some cases, the nests grow large enough to cause structural damage to the tree itself, particularly during bad storms where the weight of the nest can cause additional stress on wind-tossed branches.

=== Pendent ===
[[File:Taveta Golden-weaver nest.JPG|thumb|[[Taveta golden weaver]] building pendent nest.]]

The ''pendent'' nest is an elongated sac woven of pliable materials such as grasses and plant fibers and suspended from a branch. [[Oropendola]]s, [[cacique (bird)|cacique]]s, [[Old World oriole|oriole]]s, [[Ploceidae|weavers]] and [[sunbird]]s are among the species that weave pendent nests. In weaver birds, the nest is suspended from a single point on a branch, while other birds incorporate more than one branch to support the nest.

=== Sphere ===

The ''sphere'' nest is a roundish structure; it is completely enclosed, except for a small opening which allows access. Most spherical nests are woven out of plant material. Spider webs are also frequently used, upon which other material such as lichens may be stuck for camouflage. The [[cape penduline tit]] incorporates false entrances, the parent bird carefully making sure to close the actual entrance when leaving the nest. The entrances are lined with spider webs which help seal the openings.<ref>{{Cite journal |last=Skead |first=C. J. |date=1959 |title=A study of the Cape penduline tit ''Anthoscopus minutus minutus'' (Shaw & Nodder) |url=https://www.tandfonline.com/doi/full/10.1080/00306525.1959.9633335 |journal=Ostrich |language=en |volume=30 |issue=sup1 |pages=274–288 |doi=10.1080/00306525.1959.9633335 |bibcode=1959Ostri..30S.274S |issn=0030-6525|url-access=subscription }}</ref>

==Nest protection and sanitation==

Many species of bird conceal their nests to protect them from predators. Some species may choose nest sites that are inaccessible or build the nest so as to deter predators.{{sfn|Rudolph|Kyle|Conner|1990}} Bird nests can also act as habitats for other [[inquiline]] species which may not affect the bird directly. Birds have also evolved nest sanitation measures to reduce the effects of parasites and pathogens on nestlings.

Some aquatic species such as [[grebe]]s are very careful when approaching and leaving the nest so as not to reveal the location. Some species will use leaves to cover up the nest prior to leaving.

Ground birds such as plovers may use ''broken wing'' or ''rodent run'' displays to distract predators from nests.<ref>{{harvnb|Byrktedal|1989}}</ref>

Many species attack predators or apparent predators near their nests. [[Kingbird]]s attack other birds that come too close. In North America, [[northern mockingbird]]s, [[blue jay]]s, and [[Arctic tern]]s can peck hard enough to draw blood.<ref>{{harvnb|Gill|1995}}</ref> In Australia, a bird attacking a person near its nest is said to ''swoop'' the person. The [[Australian magpie]] is particularly well known for this behavior.<ref>{{harvnb|Kaplan|2004}}</ref>

Nests can become home to many other organisms including parasites and pathogens.<ref>{{Citation |last=Hicks |first=Ellis A. |title=Checklist and bibliography on the occurrence of insects in birds' nests |year= 1959|publisher=Iowa State College Press, Ames| url=https://archive.org/details/checklistbibliog00hick}}</ref> The excreta of the fledglings also pose a problem. In most passerines, the adults actively dispose the [[fecal sac]]s of young at a distance or consume them. This is believed to help prevent ground predators from detecting nests.<ref>{{harvnb|Petit|Petit|Petit|1989}}</ref> Young birds of prey however usually void their excreta beyond the rims of their nests.<ref>{{harvnb|Rosenfeld|Rosenfeld|Gratson|1982}}</ref> [[calliphoridae|Blowflies]] of the genus ''[[Protocalliphora]]'' have specialized to become obligate nest parasites with the maggots feeding on the blood of nestlings.<ref>{{harvnb|Sabrosky|Bennett|Whitworth|1989}}</ref>

Some birds have been shown to choose aromatic green plant material for constructing nests that may have insecticidal properties,<ref>{{harvnb|Wimberger|1984}}</ref><ref>{{harvnb|Clark|Mason|1985}}</ref> while others may use materials such as carnivore scat to repel smaller predators.<ref>{{harvnb|Schuetz|2005}}</ref> Some urban birds, house sparrows and house finches in Mexico, have adopted the use of cigarette butts which contain nicotine and other toxic substances that repel ticks and other ectoparasites.<ref>{{Cite journal |last1=Suárez-Rodríguez |first1=Monserrat |last2=Garcia |first2=Constantino Macías |date=2017 |title=An experimental demonstration that house finches add cigarette butts in response to ectoparasites |url=https://onlinelibrary.wiley.com/doi/10.1111/jav.01324 |journal=Journal of Avian Biology |language=en |volume=48 |issue=10 |pages=1316–1321 |doi=10.1111/jav.01324 |issn=0908-8857|url-access=subscription }}</ref><ref>{{cite journal|doi=10.1098/rsbl.2012.0931|pmid=23221874|pmc=3565511|title=Incorporation of cigarette butts into nests reduces nest ectoparasite load in urban birds: New ingredients for an old recipe?|journal=Biology Letters|volume=9|issue=1|pages=20120931|year=2012|last1=Suarez-Rodriguez|first1=M.|last2=Lopez-Rull|first2=I.|last3=MacIas Garcia|first3=C.}}</ref>

Some birds use pieces of snake slough in their nests.<ref>{{Citation|last=Strecker|first=John K|year=1926|title=On the use, by birds, of snakes' sloughs as nesting material|journal=Auk|volume=53|pages=501–507|url=http://sora.unm.edu/sites/default/files/journals/auk/v043n04/p0501-p0507.pdf|doi=10.2307/4075138|issue=4|url-status=live|archive-url=https://web.archive.org/web/20131224084143/http://sora.unm.edu/sites/default/files/journals/auk/v043n04/p0501-p0507.pdf|archive-date=24 December 2013|jstor=4075138}}</ref> It has been suggested that these may deter some nest predators such as squirrels.<ref>{{Citation|first1=Elizabeth C.|last1=Medlin|first2=Thomas S.|last2=Risch|title=An experimental test of snake skin use to deter nest predation|journal=The Condor|year=2006|volume=108|issue=4|pages=963–965|doi=10.1650/0010-5422(2006)108[963:AETOSS]2.0.CO;2|s2cid=86039366 |url=https://zenodo.org/record/956844|doi-access=free}}</ref>

==Colonial nesting==

[[File:PMontezumaNests03.jpg|thumb|Nesting colony of [[Montezuma oropendola]]s]]{{Main|Bird colony}}
Though most birds nest individually, some species—including [[seabird]]s, penguins, flamingos, many [[heron]]s, [[gull]]s, [[tern]]s, [[Ploceidae|weaver]], some [[corvid]]s and some [[Old World sparrow|sparrow]]s—gather together in sizeable colonies. Birds that nest colonially may benefit from increased protection against predation. They may also be able to better use food supplies, by following more successful foragers to their foraging sites.<ref>{{Harvnb|Ward|Zahavi|1973}}</ref>

== Ecological importance ==
[[File:Bird-nest (2).jpg|thumb|alt=Two bird nest close to each other|Two expired bird nest.]]
In constructing nests, birds act as [[ecosystem engineer]]s by providing a sheltered microclimate and concentrated food sources for invertebrates.<ref>{{Cite journal|last1=Boyes|first1=Douglas H.|last2=Lewis|first2=Owen T.|date=2018-08-27|title=Ecology of Lepidoptera associated with bird nests in mid-Wales, UK|journal=Ecological Entomology|volume=44|issue=1|pages=1–10|doi=10.1111/een.12669|s2cid=91557693|issn=0307-6946|doi-access=free}}</ref> A global checklist lists eighteen invertebrate orders that occur in bird nests.<ref>{{Cite journal|last1=Berner|first1=Lewis|last2=Hicks|first2=Ellis A.|date=June 1959|title=Checklist and Bibliography on the Occurrence of Insects in Birds Nests|url=http://dx.doi.org/10.2307/3492142|journal=The Florida Entomologist|volume=42|issue=2|pages=92|doi=10.2307/3492142|jstor=3492142|issn=0015-4040}}</ref>

==In human culture==
[[File:Ciconia ciconia juv small.jpg|thumb|alt=Three long-legged, long-billed black and white birds stand on a huge pile of sticks atop an artificial platform on a pole.|A human-made nest platform in Poland built as a conservation measure and to prevent storks disrupting electricity supplies through nesting on pylons. Three young [[white stork]]s are on the top of the nest and two [[Eurasian tree sparrow]]s are perching on the side of the nest.]]

Many birds may nest close to human habitations. In addition to [[nest box]]es which are often used to encourage cavity nesting birds (see below), other species have been specially encouraged : for example nesting [[white stork]]s have been protected and held in reverence in many cultures,<ref>{{Citation |last=Kushlan |first=James A. |year=1997 |title=The Conservation of Wading Birds |journal=Colonial Waterbirds |volume=20 |issue=1 |pages=129–137 |doi=10.2307/1521775 |jstor=1521775 |postscript=.}}</ref> and the nesting of [[peregrine falcon]]s on tall modern or historical buildings has captured popular interest.<ref>{{harvnb|Cade|Bird|1990}}</ref>

Colonial breeders produce [[guano]] in and around their nesting sites, which is a valuable fertilizer from the Andean Pacific coast and other areas.

The saliva nest of the [[edible-nest swiftlet]] is used to make [[Edible bird's nest|bird's nest soup]],<ref name="Couzens">{{Citation |title=Top 100 Birding Sites of the World |first=Dominic |last=Couzens |pages=85–86 |publisher=University of California Press |location=Berkeley, CA |year=2008 |isbn=978-0-520-25932-4}}</ref> long considered a delicacy in China.<ref>{{Citation |title=They Eat That?: A Cultural Encyclopedia of Weird and Exotic Food from Around the World |first1=Jonathan |last1=Deutsch |first2=Natalya |last2=Murakhver |page=17 |publisher=ABC-CLIO |year=2012 |isbn=978-0-313-38058-7 |location=Santa Barbara, CA |url=https://books.google.com/books?id=kcikMWmnQm4C&pg=PA17 |url-status=live |archive-url=https://web.archive.org/web/20130604193533/http://books.google.com/books?id=kcikMWmnQm4C&pg=PA17 |archive-date=4 June 2013 }}</ref> Collection of the swiftlet nests is big business: in one year, more than 3.5 million nests were exported from Borneo to China,<ref>{{Citation |title=Biology of Birds |first1=D. R. |last1=Khanna |first2=P. R. |last2=Yadav |page=129 |url=https://books.google.com/books?id=fDblIChi7KwC&pg=PA129 |publisher=Discovery Publishing House |location=New Delhi, India |year=2005 |isbn=978-81-7141-933-3 |url-status=live |archive-url=https://web.archive.org/web/20130603193145/http://books.google.com/books?id=fDblIChi7KwC&pg=PA129 |archive-date=3 June 2013 }}</ref> and the industry was estimated at $1&nbsp;billion US per year (and increasing) in 2008.<ref name="Couzens"/> While the collection is regulated in some areas (at the [[Gomantong Caves]], for example, where nests can be collected only from February to April or July to September), it is not in others, and the swiftlets are declining in areas where the harvest reaches unsustainable levels.<ref name="Couzens"/>

Some species of birds are considered nuisances when they nest in the proximity of human habitations. [[Feral pigeons]] are often unwelcome and sometimes also considered as a health risk.<ref>{{harvnb|Haag-Wackernagel|Moch|2004}}</ref>

The [[Beijing National Stadium]], principal venue of the [[2008 Summer Olympics]], has been nicknamed "The Bird Nest" because of its architectural design, which its designers likened to a bird's woven nest.<ref>{{cite web |url=http://www.bjghw.gov.cn/forNationalStadium/indexeng.asp#11 |title=Competition entries for design of Beijing National Stadium |publisher=Beijing Municipal Commission of Urban Planning |access-date=25 February 2008 |archive-url = https://web.archive.org/web/20080220015738/http://www.bjghw.gov.cn/forNationalStadium/indexeng.asp#11 <!-- Bot retrieved archive --> |archive-date = 20 February 2008}}</ref>

In the 19th and early 20th centuries, [[naturalist]]s often collected bird's eggs and their nests. The practice of egg-collecting or [[oology]] is now illegal in many jurisdictions worldwide; the study of bird nests is called '''[[caliology]]'''.<ref>{{Citation |last=Dixon |first=Charles | year= 1902| title= Birds' nests| publisher=Frederick A Stokes |location=New York |url=https://archive.org/details/cu31924000206114 |page=v}}</ref>

==Artificial bird nests==
[[File:Duck tube aka artificial nest tube at Peter Pond, Emsworth (P1020415).jpg|thumb|Artificial duck nest]]
Bird nests are also built by humans to help in the conservation of certain birds. For example, artificial [[swallow]] nests are generally built with plaster, wood, terracotta or stucco.<ref>[http://www.americanartifacts.com/smma/per/nesttest.htm Artificial swallow nests] {{webarchive|url=https://web.archive.org/web/20140317105512/http://www.americanartifacts.com/smma/per/nesttest.htm |date=17 March 2014 }}</ref><ref>[http://shopping.rspb.org.uk/swallow-nest.html Terracotta nests] {{webarchive|url=https://web.archive.org/web/20140317111246/http://shopping.rspb.org.uk/swallow-nest.html |date=17 March 2014 }}</ref>

Artificial nests, such as [[nest box]]es, are an important conservation tool for many species, however nest box programs rarely compare their effectiveness with individuals not using nest boxes. Red-footed falcons using nest boxes in heavily managed landscapes produced fewer fledglings than those nesting in natural nests, but also than pairs nesting in nest boxes in more natural habitats.<ref>{{cite journal |author1= Bragin, E. A. |author2= Bragin, A. E. | author3= Katzner, T. E. | year=2017| title= Demographic consequences of nestbox use for Red-footed Falcons ''Falco vespertinus'' in Central Asia | journal=Ibis| volume=159| pages=841–853| doi=10.1111/ibi.12503| issue=4}}</ref>
{{Clear}}

==References==

===Notes===
{{Reflist}}

===Cited texts===
{{Refbegin}}
* {{citation |last=Behrstock |first=Robert A. |editor-last= Elphick |editor-first= Chris |editor2-last= Dunning |editor2-first= John B. Jr. |editor3-last= Sibley |editor3-first= David |contribution= Typical Owls |title=The Sibley Guide to Bird Life & Behaviour |publisher=Christopher Helm |location=London |year=2001 |isbn=978-0-7136-6250-4}}
* {{Citation|last=Byrktedal|first=Ingvar|year=1989|title=Nest defense behavior of Lesser Golden-Plovers|journal=Wilson Bull.|volume=101|issue=4|pages=579–590|url=http://sora.unm.edu/sites/default/files/journals/wilson/v101n04/p0579-p0590.pdf}}
* {{Citation|last1=Cade|first1=T.J.|last2=Bird|first2=D.M.|year=1990|title=Peregrine Falcons (''Falco peregrinus'') nesting in an urban environment: a review|journal=Can. Field-Nat.|volume=104|issue=2 |pages=209–218|doi=10.5962/p.356349 |doi-access=free}}
* {{citation |editor-last= Campbell |editor-first= Bruce |editor2-last= Lack |editor2-first= Elizabeth |title=A Dictionary of Birds |year=1985 |publisher=T and A D Poyser |location=Carlton, England |isbn=978-0-85661-039-4}}
* {{Citation|last1=Clark|first1=L.|first2=J. Russell|last2=Mason|year=1985|title=Use of nest material as insecticidal and anti-pathogenic agents by the European Starling|journal=Oecologia|volume=67|issue=2|pages=169–176|doi=10.1007/BF00384280|pmid=28311305|bibcode=1985Oecol..67..169C|s2cid=32307579}}
* {{citation |last=Cohn-Haft |first=Mario |contribution= Family Nyctibiidae (Potoos) |editor-last=del Hoyo |editor-first=Josep |editor2-last= Elliott |editor2-first= Andrew |editor3-last= Sargatal |editor3-first= Jordi |title=Handbook of Birds of the World, Volume 5: Barn-owls to Hummingbirds |year=1999 |publisher=Lynx Edicions |location=Barcelona |isbn=978-84-87334-25-2|title-link=Handbook of Birds of the World }}
* {{citation |last=Collar |first=N. J. |contribution= Family Trogonidae (Trogons) |editor-last=del Hoyo |editor-first=Josep |editor2-last= Elliott |editor2-first= Andrew |editor3-last= Sargatal |editor3-first= Jordi |title=Handbook of Birds of the World, Volume 6: Mousebirds to Hornbills |year=2001 |publisher=Lynx Edicions |location=Barcelona |isbn=978-84-87334-30-6|title-link=Handbook of Birds of the World }}
* {{Citation|doi=10.2307/1369932|last=Collias|first=Nicholas E.|year=1997|title=On the origin and evolution of nest building by passerine birds|
journal=Condor|volume=99|issue=2|pages=253–270|url=http://sora.unm.edu/sites/default/files/journals/condor/v099n02/p0253-p0270.pdf|jstor=1369932}}
* {{citation |last=Conner |first=Richard N. |title=Orientation of entrances to woodpecker nest cavities |year=1975 |journal=Auk |volume=92 |pages=371–374 |doi=10.2307/4084566 |issue=2|jstor=4084566 |doi-access=free }}
* {{citation |last=del Hoyo |first=Josep |contribution= Family Phoenicopteridae (Flamingos) |editor-last=del Hoyo |editor-first=Josep |editor2-last= Elliott |editor2-first= Andrew |editor3-last= Sargatal |editor3-first= Jordi |title=Handbook of Birds of the World, Volume 1: Ostrich to Ducks |year=1992 |publisher=Lynx Edicions |location=Barcelona |isbn=978-84-87334-10-8|title-link=Handbook of Birds of the World }}
* {{citation |editor-last=del Hoyo |editor-first=Josep |editor2-last= Elliott |editor2-first= Andrew |editor3-last= Sargatal |editor3-first= Jordi |title=Handbook of Birds of the World, vol. 3 |year=1996 |publisher=Lynx Edicions |location=Barcelona |isbn=978-84-87334-20-7|title-link=Handbook of Birds of the World }}
* {{citation |last1=Ehrlich |first1=Paul R. |author-link=Paul R. Ehrlich |last2=Dobkin |first2=David S. |last3=Wheye |first3=Darryl |last4=Pimm |first4=Stuart L. |title=The Birdwatcher's Handbook |year=1994 |publisher=Oxford University Press |location=Oxford |isbn=978-0-19-858407-0 |url=https://archive.org/details/birdwatchershand00ehrl }}
* {{citation |last=Elliott |first=Andrew |contribution= Family Megapodiidae (Megapodes) |editor-last=del Hoyo |editor-first=Josep |editor2-last= Elliott |editor2-first= Andrew |editor3-last= Sargatal |editor3-first= Jordi |title=Handbook of Birds of the World, Volume 2: New World Vultures to Guineafowl |year=1994 |publisher=Lynx Edicions |location=Barcelona |isbn=978-84-87334-15-3|title-link=Handbook of Birds of the World }}
* {{citation |title=Animal Architects: Building and the Evolution of Intelligence |first1=James L |last1=Gould |first2=Carol Grant |last2=Gould |publisher=Basic Books |location=New York, NY |year=2007 |isbn=978-0-465-02782-8 |url=https://archive.org/details/animalarchitects00goul }}
* {{Citation |title=Avian Incubation in a Hot Environment |series=Ornithological Monographs |volume=30 |first=Gilbert |last=Grant |year=1982 |publisher=[[American Ornithologists' Union]] |location=Washington, DC |isbn=978-0-943610-30-6 |url=http://sora.unm.edu/node/155}}
* {{citation |last1=Haag-Wackernagel |first1=D |last2= Moch |first2=H. |title=Health hazards posed by feral pigeons |journal=J. Infect. |year=2004 |volume=48 |pages=307–313 |doi=10.1016/j.jinf.2003.11.001 |pmid=15066331 |issue=4}}
* {{citation |last=Gill |first=Frank B. |year=1995 |title=Ornithology |publisher=Macmillan |page=383 |isbn=978-0-7167-2415-5 |url=https://books.google.com/books?id=jFfs1jsPfwgC&pg=PA383 |access-date=16 December 2009}}
* {{citation |last=Hansell |first=Mike |title=Bird Nests and Construction Behaviour |year=2000 |publisher=Cambridge University Press |isbn=978-0-521-01764-0 |url= https://archive.org/details/birdnestsconstru0000hans}}
* {{citation |last1= Harrap |first1= Simon |last2= Quinn |first2= David |title=Tits, Nuthatches & Treecreepers |year=1996 |publisher=Christopher Helm |location=London |isbn=978-0-7136-3964-3}}
* {{citation |last=Hogan |first=C. Michael |date=2010 |url= http://www.eoearth.org/article/Abiotic_factor?topic=49461 |title=Abiotic factor |encyclopedia=Encyclopedia of Earth |editor1= Emily Monosson |editor2=C. Cleveland |publisher=National Council for Science and the Environment |location=Washington DC|archive-url=https://web.archive.org/web/20130608071757/http://www.eoearth.org/article/Abiotic_factor?topic=49461 |archive-date=8 June 2013 }}
* {{citation |last=Jaramillo |first=Alvaro |editor-last= Elphick |editor-first= Chris |editor2-last= Dunning |editor2-first= John B. Jr. |editor3-last= Sibley |editor3-first= David |contribution= Blackbirds, Orioles and Allies |title=The Sibley Guide to Bird Life & Behaviour |publisher=Christopher Helm |location=London |year=2001 |isbn=978-0-7136-6250-4}}
* {{citation |last1=Juniper |first1= Tony |last2= Parr |first2= Mike |title=Parrots: A Guide to the Parrots of the World |location=London |publisher=Christopher Helm |year=2003 |isbn=978-0-7136-6933-6}}
* {{citation |last=Kaplan |first=Gisela |title=Australian Magpie: Biology and Behaviour of an Unusual Songbird |publisher=CSIRO Publishing |location=Melbourne, Victoria |year=2004 |page=121 |isbn=978-0-643-09068-2 |url=https://books.google.com/books?id=ap6gjCjr5lMC&pg=PA121|access-date=16 December 2009}}
* {{citation |last=Kemp |first=A. C. |contribution= Family Bucerotidae (Hornbills) |editor-last=del Hoyo |editor-first=Josep |editor2-last= Elliott |editor2-first= Andrew |editor3-last= Sargatal |editor3-first= Jordi |title=Handbook of Birds of the World, Volume 6: Mousebirds to Hornbills |year=2001 |publisher=Lynx Edicions |location=Barcelona |isbn=978-84-87334-30-6|title-link=Handbook of Birds of the World }}
* {{Citation|last1=Petit|first1=Kenneth E.|last2=Petit|first2=Lisa J.|last3=Petit|first3=Daniel R.|year=1989|title=Fecal Sac Removal: Do the Pattern and Distance of Dispersal Affect the Chance of Nest Predation?|journal=The Condor|volume=91|issue=2|pages=479–482 |doi=10.2307/1368331 |url=http://sora.unm.edu/sites/default/files/journals/condor/v091n02/p0479-p0482.pdf|jstor=1368331}}
* {{citation |last=Reed |first=J. Michael |editor-last= Elphick |editor-first= Chris |editor2-last= Dunning |editor2-first= John B. Jr. |editor3-last= Sibley |editor3-first= David |contribution= Woodpeckers and Allies |title=The Sibley Guide to Bird Life & Behaviour |publisher=Christopher Helm |location=London |year=2001 |isbn=978-0-7136-6250-4}}
* {{citation |last1=Rasmussen |first1=Pamela C. |last2=Collar |first2=Nigel J. |contribution= Family Bucconidae (Puffbirds) |editor-last=del Hoyo |editor-first=Josep |editor2-last= Elliott |editor2-first= Andrew |editor3-last= Sargatal |editor3-first= Jordi |title=Handbook of Birds of the World, Volume 7: Jacamars to Woodpeckers |year=2002 |publisher=Lynx Edicions |location=Barcelona |isbn=978-84-87334-37-5|title-link=Handbook of Birds of the World }}
* {{Citation|first1=R.N.|last1=Rosenfeld|first2=A. J.|last2=Rosenfeld|first3=M. W.|last3=Gratson|year=1982|title=Unusual Nest Sanitation by a Broad-Winged Hawk|url=http://sora.unm.edu/sites/default/files/journals/wilson/v094n03/p0365-p0366.pdf|journal=The Wilson Bulletin|volume=94|issue=3|pages=2365–366}}
* {{Citation|last1=Rudolph|first1=D. C.|first2=H.|last2=Kyle|first3=R. N.|last3=Conner |year=1990 |title=Red-cockaded woodpeckers vs. Rat Snakes: The effectiveness of the resin barrier |journal=Wilson Bull. |volume=102 |issue=l |pages=14–22 |url=http://sora.unm.edu/sites/default/files/journals/wilson/v102n01/p0014-p0022.pdf}}
* {{Citation|last1=Sabrosky|first1=Curtis W.|last2=Bennett|first2=G. F.|last3=Whitworth|first3=T. L.|year=1989|title=Bird blow-flies (''Protocalliphora'') (Diptera: Calliphoridae) in North America with notes on the Palearctic species |publisher=Smithsonian Institution Press |location=Washington, DC}}
* {{Citation|last=Schuetz|first=Justin G.|year=2005|title=Common waxbills use carnivore scat to reduce the risk of nest predation|journal=Behavioral Ecology|volume=16|issue=1|pages=133–137|url=http://beheco.oxfordjournals.org/cgi/content/full/16/1/133|archive-url=https://archive.today/20130113053113/http://beheco.oxfordjournals.org/cgi/content/full/16/1/133|url-status=dead|archive-date=13 January 2013|doi=10.1093/beheco/arh139|doi-access=free}}
* {{citation |last=Seng |first=William J. |editor-last= Elphick |editor-first= Chris |editor2-last= Dunning |editor2-first= John B. Jr. |editor3-last= Sibley |editor3-first= David |contribution= Flamingos |title=The Sibley Guide to Bird Life & Behaviour |publisher=Christopher Helm |location=London |year=2001 |isbn=978-0-7136-6250-4}}
* {{citation |last1=Short |first1=Lester L. |last2=Horne |first2=Jennifer F. M. |contribution= Family Capitonidae (Barbets) |editor-last=del Hoyo |editor-first=Josep |editor2-last= Elliott |editor2-first= Andrew |editor3-last= Sargatal |editor3-first= Jordi |title=Handbook of Birds of the World, Volume 7: Jacamars to Woodpeckers |year=2002a |publisher=Lynx Edicions |location=Barcelona |isbn=978-84-87334-37-5|title-link=Handbook of Birds of the World }}
* {{citation |last1=Short |first1=Lester L. |last2=Horne |first2=Jennifer F. M. |contribution= Family Indicatoridae (Honeyguides) |editor-last=del Hoyo |editor-first=Josep |editor2-last= Elliott |editor2-first= Andrew |editor3-last= Sargatal |editor3-first= Jordi |title=Handbook of Birds of the World, Volume 7: Jacamars to Woodpeckers |year=2002b |publisher=Lynx Edicions |location=Barcelona |isbn=978-84-87334-37-5|title-link=Handbook of Birds of the World }}
* {{citation |last1=Skowron|first1=C|last2=Kern|first2=M.|title=The insulation in nests of selected North-American songbirds|journal=Auk|year=1980|volume=97|issue=4|pages=816–824|doi=10.1093/auk/97.4.816}}
* {{citation |last1= Ward |first1= P. |last2= Zahavi |first2= A. |year=1973 |title=The importance of certain assemblages of birds as "information centers" for food finding |journal=Ibis |volume=115 |issue= 4 |pages=517–534 |doi=10.1111/j.1474-919X.1973.tb01990.x}}
* {{citation |last1=Whittow, F.N.|last2=Berger|first2=A.J.|title=Heat loss from the nest of the Hawaiian honeycreeper, 'Amakihi'|journal=Wilson Bulletin|year=1977|volume=89|pages=480–483}}
* {{Citation|last=Wimberger|first=P. H.|year=1984|title=The use of green plant material in bird nests to avoid ectoparasites|journal=Auk|volume=101|issue=3|pages=615–616 |url=http://sora.unm.edu/sites/default/files/journals/auk/v101n03/p0615-p0618.pdf|doi=10.1093/auk/101.3.615}}
* {{citation |last=Woodall |first=Peter F. |contribution= Family Alcedinidae (Kingfishers) |editor-last=del Hoyo |editor-first=Josep |editor2-last= Elliott |editor2-first= Andrew |editor3-last= Sargatal |editor3-first= Jordi |title=Handbook of Birds of the World, Volume 6: Mousebirds to Hornbills |year=2001 |publisher=Lynx Edicions |location=Barcelona |isbn=978-84-87334-30-6|title-link=Handbook of Birds of the World }}
{{Refend}}

==External links==
{{Commons category|Bird nests}}
{{EB1911 poster|Nidification}}
* [http://people.eku.edu/ritchisong/birdnests.html Lecture notes on bird nesting]
* [https://web.archive.org/web/20070808102521/http://dnr.state.il.us/lands/education/wild/birdnest.htm Department of natural resources Illinois state]
* [http://www.earthlife.net/birds/nests.html Earthlife site on bird nests]
* [http://www.prbo.org/cms/docs/edu/activity4.pdf Point Reyes Bird Observatory Teacher Resource Packet—Activity 4: Building Bird Nests]
* {{Cite Americana |last=Ingersoll |first=Ernest |authorlink=Ernest Ingersoll |wstitle=Birds, Nests of |short=x}}
* {{Cite NIE|wstitle=Nidification |short=x}}

{{Birds|state=collapsed}}

{{DEFAULTSORT:Bird Nest}}
[[Category:Shelters built or used by animals]]
[[Category:Bird breeding]]
[[Category:Articles containing video clips]]