Editing Bird nest (section)

=== 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>