Bird 3410 225793715 2008-07-15T12:51:00Z Apteva 7203312 /* Economic importance */ {{pp-semi-protected|small=yes}} {{otheruses}} {{redirect|Aves}} {{Taxobox | name = Birds | fossil_range = {{fossil range|160}}Late [[Jurassic]] – Recent | image = Phalacrocorax-auritus-007.jpg | image_width = 240px | image_caption = [[Double-crested Cormorant]], ''Phalacrocorax auritus'' | regnum = [[Animal]]ia | phylum = [[Chordata]] | subphylum = [[Vertebrata]] | unranked_classis = [[Archosauria]] | classis = '''Aves''' | classis_authority = [[Carolus Linnaeus|Linnaeus]], 1758 | subdivision_ranks = [[Order (biology)|Orders]] | subdivision = About two dozen - see [[#Modern bird orders|section below]] }} {{Spoken Wikipedia|Bird_(Intro).ogg|2008-01-05}} '''Birds''' ([[class (biology)|class]] '''Aves''') are [[Bipedalism|biped]]al, endothermic ([[warm-blooded]]), [[vertebrate]] animals that lay [[egg (biology)|eggs]]. There are around 10,000 living species, making them the most diverse [[tetrapod]] vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Birds range in size from the {{convert|5|cm|in|sigfig=1|abbr=on}} [[Bee Hummingbird]] to the {{convert|2.7|m|sigfig=1|abbr=on}} [[Ostrich]]. The fossil record indicates that birds [[evolution|evolved]] from [[Theropoda|theropod]] [[dinosaur]]s during the [[Jurassic]] period, around 150–200 Ma (million years ago), and the earliest known bird is the Late Jurassic ''[[Archaeopteryx]]'', ''c'' 155–150 Ma. Most [[paleontologist]]s regard birds as the only [[clade]] of dinosaurs that survived the [[Cretaceous–Tertiary extinction event]] approximately 65.5 Ma. Modern birds are [[body plan|characterised]] by feathers, a beak with no teeth, the laying of hard-shelled eggs, a high [[metabolism|metabolic]] rate, a four-chambered heart, and a lightweight but strong [[Bird skeleton|skeleton]]. All birds have forelimbs modified as wings and most can [[bird flight|fly]], with some exceptions including [[ratite]]s, [[penguin]]s, and a number of diverse [[Endemism in birds|endemic]] island species. Birds also have unique [[digestive system|digestive]] and [[respiratory system]]s that are highly adapted for flight. Some birds, especially [[corvids]] and [[parrots]], are among the most intelligent animal species; a number of bird species have been observed manufacturing and using [[tools]], and many social species exhibit [[cultural]] transmission of knowledge across generations. Many species undertake long distance annual [[bird migration|migrations]], and many more perform shorter irregular movements. Birds are social; they communicate using visual signals and through calls and [[bird song|songs]], and participate in social behaviours including [[Helpers at the nest|cooperative breeding]] and hunting, [[Flocking (behavior)|flocking]], and [[Mobbing behavior|mobbing]] of predators. The vast majority of bird species are [[socially monogamous]], usually for one breeding season at a time, sometimes for years, but rarely for life. Other species have breeding systems that are [[polygyny|polygynous]] ("many females") or, rarely, [[polyandry|polyandrous]] ("many males"). Eggs are usually laid in a nest and [[Avian incubation|incubated]] by the parents. Most birds have an extended period of parental care after hatching. Many species are of economic importance, mostly as sources of food acquired through hunting or farming. Some species, particularly [[songbird]]s and [[parrot]]s, are popular as pets. Other uses include the harvesting of [[guano]] (droppings) for use as a [[fertiliser]]. Birds [[List of fictional birds|figure prominently]] in all aspects of human culture from religion to poetry to popular music. About 120–130 species have become [[extinction|extinct]] as a result of human activity since the 17th century, and hundreds more before then. Currently about 1,200 species of birds are threatened with extinction by human activities, though efforts are underway to [[bird conservation|protect]] them. ==Evolution and taxonomy== {{main|Bird evolution}} [[Image:SArchaeopteryxBerlin2.jpg|thumb|right|''[[Archaeopteryx]]'', the earliest known bird]] The first [[biological classification|classification]] of birds was developed by [[Francis Willughby]] and [[John Ray]] in their 1676 volume ''Ornithologiae''.<ref>{{cite book |last=del Hoyo |first=Josep |coauthors=Andy Elliott & Jordi Sargatal |title= [[Handbook of Birds of the World]], Volume 1: Ostrich to Ducks |year= 1992 |publisher=[[Lynx Edicions]] |location= Barcelona |isbn=84-87334-10-5}}</ref> [[Carolus Linnaeus]] modified that work in 1758 to devise the taxonomic classification system currently in use.<ref> {{la icon}} {{cite book | last = Linnaeus | first = Carolus | authorlink = Carolus Linnaeus | title = [[Systema Naturae|Systema naturae per regna tria naturae, secundum classes, ordines, genera, species, cum characteribus, differentiis, synonymis, locis. Tomus I. Editio decima, reformata]] | publisher = Holmiae. (Laurentii Salvii) | date = 1758 | pages = 824 | url=}}</ref> Birds are categorised as the [[Class (biology)|biological class]] Aves in [[Linnaean taxonomy]]. [[Phylogenetic taxonomy]] places Aves in the dinosaur [[clade]] [[Theropoda]].<ref name="Theropoda">{{cite journal |last=Livezey |first=Bradley C. |coauthors=Richard L. Zusi |month=January |year=2007 |title=Higher-order phylogeny of modern birds (Theropoda, Aves: Neornithes) based on comparative anatomy. II. Analysis and discussion |journal=[[Zoological Journal of the Linnean Society]] |volume=149 |issue=1 |pages= 1–95 |doi=10.1111/j.1096-3642.2006.00293.x}}</ref> Aves and a sister group, the clade [[Crocodilia]], together are the sole living members of the [[reptile]] clade [[Archosauria]]. [[Phylogenetics|Phylogenetically]], Aves is commonly defined as all descendants of the most recent common ancestor of modern birds and ''[[Archaeopteryx|Archaeopteryx lithographica]]''.<ref> {{cite book |last= Padian| first= Kevin|authorlink=Kevin Padian|coauthor=L.M. Chiappe Chiappe LM |editor= [[Philip J. Currie]] & Kevin Padian (eds.) |title= Encyclopedia of Dinosaurs|year= 1997|publisher= [[Academic Press]]|location= San Diego|pages= 41–96|chapter= Bird Origins|isbn=0-12-226810-5}} </ref> ''Archaeopteryx'', from the [[Kimmeridgian]] stage of the [[Late Jurassic]] (some 155–150 million years ago), is the earliest known bird under this definition. Others, including [[Jacques Gauthier]] and adherents of the [[Phylocode]] system, have defined Aves to include only the modern bird groups, excluding most groups known only from fossils, and assigning them, instead, to the [[Avialae]]<ref>{{cite book |last= Gauthier |first= Jacques|editor= Kevin Padian |title= The Origin of Birds and the Evolution of Flight|Series= Memoirs of the California Academy of Science '''8'''|year= 1986|pages= 1–55|chapter= Saurischian Monophyly and the origin of birds|isbn=0-940228-14-9}}</ref> in part to avoid the uncertainties about the placement of ''Archaeopteryx'' in relation to animals traditionally thought of as theropod dinosaurs.<!-- See WP:RS [http://www.phylonames.org/forum/viewtopic.php?t=7]--><!--Mayr et al 2005 "A well-preserved Archaeopteryx specimen with theropod features" + comment + Mayr's comment on the comment--> All modern birds lie within the [[subclass (biology)|subclass]] [[Neornithes]], which has two subdivisions: the [[Paleognathae]], containing mostly flightless birds like [[ostrich]]es, and the wildly diverse [[Neognathae]], containing all other birds.<ref name="Theropoda"/> These two subdivisions are often given the [[taxonomic rank|rank]] of [[superorder]],<ref>{{cite web |url=http://people.eku.edu/ritchisong/birdbiogeography1.htm |title=Bird biogeography |accessdate=2008-04-10 |format= |work=}}</ref> although Livezey & Zusi assigned them "cohort" rank.<ref name="Theropoda"/> Depending on the [[alpha taxonomy|taxonomic]] viewpoint, the number of known living bird species varies anywhere from 9,800<ref>{{cite book | title=[[The Clements Checklist of Birds of the World]] | first= James F. | last = Clements |edition=6th edition | authorlink=James Clements |location=Ithaca | publisher = [[Cornell University Press]] | date = 2007 | isbn= 978-0-8014-4501-9 }}</ref> to 10,050.<ref>{{cite book |last=Gill |first=Frank |authorlink=Frank Gill (ornithologist) |year=2006 |title=Birds of the World: Recommended English Names |location=Princeton |publisher=[[Princeton University Press]] |isbn=978-0-691-12827-6}}</ref> ===Dinosaurs and the origin of birds=== {{main|Origin of birds}} [[Image:Confuchisornis sanctus.JPG|thumb|left|''[[Confuciusornis]]'', a Cretaceous bird from [[China]]]] Fossil evidence and intensive biological analyses have demonstrated beyond any reasonable doubt that birds are [[Theropoda|theropod]] [[Dinosauria|dinosaurs]]. More specifically, they are members of [[Maniraptora]], a group of theropods which includes [[dromaeosaur]]s and [[Oviraptoridae|oviraptorids]], among others.<ref>{{cite book |last=Paul |first=Gregory S. |authorlink=Gregory S. Paul |chapter=Looking for the True Bird Ancestor |year=2002 |title=Dinosaurs of the Air: The Evolution and Loss of Flight in Dinosaurs and Birds |location=Baltimore |publisher=John Hopkins University Press |isbn=0-8018-6763-0 |pages=171–224}}</ref> As scientists discover more non-avian theropods that are closely related to birds, the previously clear distinction between non-birds and birds has become blurred. Recent discoveries in the [[Liaoning]] Province of northeast [[People's Republic of China|China]], which demonstrate that many small [[Feathered dinosaurs|theropod dinosaurs had feathers]], contribute to this ambiguity.<ref>{{cite book |last=Norell |first=Mark |coauthors=Mick Ellison |year=2005 |title=Unearthing the Dragon: The Great Feathered Dinosaur Discovery |location=New York |publisher=Pi Press |isbn=0-13-186266-9| pages=}}</ref> The consensus view in contemporary [[paleontology]] is that the birds, [[Aves]], are the closest relatives of the [[deinonychosaur]]s, which include [[dromaeosaurid]]s and [[troodontid]]s. Together, these three form a group called [[Paraves]]. The [[basal (phylogenetics)|basal]] [[dromaeosaur]] ''[[Microraptor]]'' has features which may have enabled it to glide or fly. The most basal deinonychosaurs are very small. This evidence raises the possibility that the ancestor of all paravians may have been [[arborea]]l, and/or may have been able to glide.<ref name=AHTetal07>{{cite journal |last=Turner |first=Alan H. |coauthors= Pol, Diego; Clarke, Julia A.; Erickson, Gregory M.; and Norell, Mark |year=2007 |title=A basal dromaeosaurid and size evolution preceding avian flight |url=http://www.sciencemag.org/cgi/reprint/317/5843/1378.pdf |format=pdf |journal=[[Science (journal)|Science]]|volume=317 |pages=1378–1381 |doi=10.1126/science.1144066 |pmid=17823350 }}</ref><ref name="xuetal2003">{{cite journal|author=Xing, X., Zhou, Z., Wang, X., Kuang, X., Zhang, F., and Du, X.|date=2003|title=Four-winged dinosaurs from China|journal=[[Nature (journal)|Nature]]|volume=421|issue=6921|pages=335–340|doi=10.1038/nature01342}}</ref> The [[Late Jurassic]] ''[[Archaeopteryx]]'' is well-known as one of the first [[transitional fossil]]s to be found and it provided support for the theory of [[evolution]] in the late 19th century. ''[[Archaeopteryx]]'' has clearly reptilian characters: teeth, clawed fingers, and a long, lizard-like tail, but it has finely preserved wings with flight feathers identical to those of modern birds. It is not considered a direct ancestor of modern birds, but is the oldest and most primitive member of [[Aves]] or [[Avialae]], and it is probably closely related to the real ancestor. It has even been suggested that ''Archaeopteryx'' was a dinosaur that was no more closely related to birds than were other dinosaur groups,<ref name="Thulborn1984">{{cite journal|author=Thulborn, R.A.|date=1984|title=The avian relationships of ''Archaeopteryx'', and the origin of birds|journal=Zoological Journal of the Linnean Society|volume=82|pages=119–158|doi=10.1111/j.1096-3642.1984.tb00539.x}}</ref> and that ''[[Avimimus]]'' was more likely to be the ancestor of all birds than ''Archaeopteryx''.<ref name="Kurzanov1987">{{cite journal|author=Kurzanov, S.M.|date=1987|title=Avimimidae and the problem of the origin of birds|journal=Transactions of the joint Soviet - Mongolian Paleontological Expedition|volume=31|pages=31–94}}</ref> ====Alternative theories and controversies==== There have been many controversies in the study of the origin of birds. Early disagreements included whether birds evolved from [[dinosaur]]s or more primitive [[archosaur]]s. Within the dinosaur camp there were disagreements as to whether [[ornithischian]] or [[theropod]] dinosaurs were the more likely ancestors.<ref name="Heilmann1927">Heilmann, Gerhard. "The origin of birds" (1927) "Dover Publications", New York.</ref> Although [[ornithischia]]n (bird-hipped) dinosaurs share the hip structure of modern birds, birds are thought to have originated from the [[saurischia]]n (lizard-hipped) dinosaurs, and therefore evolved their hip structure [[Analogy (biology)|independently]].<ref>{{cite journal |last=Rasskin-Gutman |first=Diego |coauthors=Angela D. Buscalioni |month=March |year=2001 |title=Theoretical morphology of the Archosaur (Reptilia: Diapsida) pelvic girdle |journal=[[Paleobiology (journal)|Paleobiology]] |volume=27 |issue=1 |pages=59–78|doi=10.1666/0094-8373(2001) |doi_brokendate=2008-06-28}}</ref> In fact, a bird-like hip structure evolved a third time among a peculiar group of theropods known as the [[Therizinosauridae]]. Scientists [[Larry Martin]] and [[Alan Feduccia]] believe that birds are not dinosaurs, but that birds evolved from early [[archosaur]]s like ''[[Longisquama]]''. The majority of their publications argued that the similarities between birds and [[maniraptora]]n dinosaurs were convergent, and that the two were unrelated. In the late 1990s the evidence that birds were [[maniraptora]]ns became almost indisputable, so Martin and Feduccia adopted a modified version of a hypothesis by dinosaur artist [[Gregory S. Paul]]; where maniraptorans are secondarily flightless birds but,<ref>{{cite book |author=Paul, Gregory S. |title=Dinosaurs of the air: the evolution and loss of flight in dinosaurs and birds |publisher=Johns Hopkins University Press |location=Baltimore |year=2002 |pages=224-258 |isbn=0-8018-6763-0 |oclc= |doi=}}</ref> in their version, birds evolved directly from [[Longisquama]]. Thus birds are still not dinosaurs, but neither are most of the known species that are currently classified as [[theropod]] dinosaurs. [[Maniraptora]]ns are, instead, flightless, [[archosaurian]], birds.<ref>{{cite journal |last=Feduccia |first=Alan |coauthors=Theagarten Lingham-Soliar, J. Richard Hinchliffe |month=November |year= 2005|title=Do feathered dinosaurs exist? Testing the hypothesis on neontological and paleontological evidence |journal=Journal of Morphology |volume=266 |issue=2 |pages=125–66 |doi=10.1002/jmor.10382 |pmid=16217748}}</ref> This theory is contested by most [[palaeontology|paleontologists]].<ref>{{cite journal |last=Prum |first=Richard O. |month=April |year=2003 |title=Are Current Critiques Of The Theropod Origin Of Birds Science? Rebuttal To Feduccia 2002 |journal=[[The Auk]] |volume=120 |issue=2 |pages=550–61 |url=http://links.jstor.org/sici?sici=0004-8038(200304)120:2%3C550:ACCOTT%3E2.0.CO;2-0 |doi=10.1642/0004-8038(2003)120[0550:ACCOTT]2.0.CO;2}}</ref> The features cited as evidence of flightlessness are interpreted by mainstream paleontologists as [[exaptation]]s, or "pre-adaptations", that [[maniraptora]]ns inherited from their common ancestor with birds. [[Protoavis|''Protoavis texensis'']], was described in 1991 as a bird older than [[Archaeopteryx]]. Critics have indicated that the fossil is poorly preserved, extensively reconstructed, and may be a [[chimera]] (made up of fossilized bones from several different kinds of animals). The braincase is most likely that of a very early [[coelurosaur]]<ref>{{cite journal |last=Zhou |first=Zhonghe |month=October |year=2004 |title=The origin and early evolution of birds: discoveries, disputes, and perspectives from fossil evidence |journal=[[Die Naturwissenschaften]] |volume=91 |issue=10 |pages=455–71 |doi=10.1007/s00114-004-0570-4}}</ref> ===Early evolution of birds=== {{Seealso|List of fossil birds}} {{userboxtop| toptext=&nbsp;}} {{clade|style=font-size:75% |label1=Aves&nbsp; |1={{clade |1=''[[Archaeopteryx]]'' |label2=&nbsp;[[Pygostylia]]&nbsp; |2={{clade |1=[[Confuciusornithidae]] |label2=&nbsp;[[Ornithothoraces]]&nbsp; |2={{clade |1=[[Enantiornithes]] |label2=&nbsp;[[Ornithurae]]&nbsp; |2={{clade |1=[[Hesperornithiformes]] |2=[[Neornithes]] }} }} }} }} }} <center><small>Basal bird phylogeny simplified after Chiappe, 2007<ref name="chiappe2007">{{cite book |last=Chiappe |first=Luis M. |year=2007 |title=Glorified Dinosaurs: The Origin and Early Evolution of Birds |location=Sydney |publisher=University of New South Wales Press |isbn=978-0-86840-413-4}}</ref></small></center> {{userboxbottom}} Birds diversified into a wide variety of forms during the [[Cretaceous Period]].<ref name="chiappe2007"/> Many groups retained [[symplesiomorphy|primitive characteristics]], such as clawed wings and teeth, though the latter were lost independently in a number of bird groups, including [[modern birds]] (Neornithes). While the earliest forms, such as ''Archaeopteryx'' and ''[[Jeholornis]]'', retained the long bony tails of their ancestors,<ref name="chiappe2007"/> the tails of more advanced birds were shortened with the advent of the [[pygostyle]] bone in the [[clade]] Pygostylia. The first large, diverse lineage of short-tailed birds to evolve were the [[Enantiornithes]], or "opposite birds", so named because the construction of their shoulder bones was in reverse to that of modern birds. Enantiornithes occupied a wide array of ecological niches, from sand-probing shorebirds and fish-eaters to tree-dwelling forms and seed-eaters.<ref name="chiappe2007"/> More advanced lineages also specialised in eating fish, like the superficially [[gull]]-like subclass of [[Ichthyornithes]] ("fish birds").<ref> {{cite journal |last=Clarke |first=Julia A. |coauthors= |month=September |year=2004 |title=Morphology, Phylogenetic Taxonomy, and Systematics of ''Ichthyornis'' and ''Apatornis'' (Avialae: Ornithurae) |journal=Bulletin of the American Museum of Natural History |volume=286 |pages=1–179 |doi= |url=http://digitallibrary.amnh.org/dspace/bitstream/2246/454/1/B286.pdf}}</ref> One order of Mesozoic seabirds, the [[Hesperornithiformes]], became so well adapted to hunting fish in marine environments that they lost the ability to fly and became primarily aquatic. Despite their extreme specialisations, the Hesperornithiformes represent some of the closest relatives of modern birds.<ref name="chiappe2007"/> ===Radiation of modern birds=== {{Seealso|Sibley-Ahlquist taxonomy|dinosaur classification}} Containing all modern birds, the subclass Neornithes is, due to the discovery of ''[[Vegavis]]'', now known to have evolved into some basic lineages by the end of the Cretaceous<!--see also Historical Biology 18:205--><ref>{{cite journal |last=Clarke |first=Julia A. |coauthors=Claudia P. Tambussi, Jorge I. Noriega, Gregory M. Erickson and Richard A. Ketcham |month=January |year=2005 |title=Definitive fossil evidence for the extant avian radiation in the Cretaceous |journal=[[Nature (journal)|Nature]] |volume=433 |issue= |pages=305–308 |doi=10.1038/nature03150 |pmid=15662422 |url=http://www.digimorph.org/specimens/Vegavis_iaai/nature03150.pdf}} [http://www.nature.com/nature/journal/v433/n7023/suppinfo/nature03150.html Supporting information]</ref> and is split into two superorders, the [[Paleognathae]] and [[Neognathae]]. The paleognaths include the [[tinamou]]s of [[Central America|Central]] and [[South America]] and the [[ratite]]s. The basal divergence from the remaining Neognathes was that of the [[Galloanserae]], the superorder containing the [[Anseriformes]] ([[duck]]s, [[goose|geese]], [[swan]]s and [[screamer]]s) and the [[Galliformes]] (the [[pheasant]]s, [[grouse]], and their allies, together with the [[mound builder (bird)|mound builders]] and the [[guan (bird)|guan]]s and their allies). The dates for the splits are much debated by scientists. It is agreed that the Neornithes evolved in the Cretaceous, and that the split between the Galloanseri from other Neognathes occurred before the [[Cretaceous–Tertiary extinction event|K–T extinction event]], but there are different opinions about whether the [[Evolutionary radiation|radiation]] of the remaining Neognathes occurred before or after the extinction of the other dinosaurs.<ref name="Ericson">{{cite journal |last=Ericson |first=Per G.P. |coauthors=Cajsa L. Anderson, Tom Britton ''et al.'' |month=December |year=2006 |title=Diversification of Neoaves: Integration of molecular sequence data and fossils |journal=[[Biology Letters]] |volume=2 |issue=4 |pages=543–547 |doi=10.1098/rsbl.2006.0523 |pmid=17148284 |url=http://www.senckenberg.de/files/content/forschung/abteilung/terrzool/ornithologie/neoaves.pdf}}</ref> This disagreement is in part caused by a divergence in the evidence; molecular dating suggests a Cretaceous radiation, while [[fossil]] evidence supports a [[Tertiary]] radiation. Attempts to reconcile the molecular and fossil evidence have proved controversial.<ref name="Ericson"/><ref>{{cite journal |last=Brown |first=Joseph W. |coauthors=Robert B. Payne, David P. Mindell |month=June |year=2007 |title=Nuclear DNA does not reconcile 'rocks' and 'clocks' in Neoaves: a comment on Ericson ''et al.'' |journal=[[Biology Letters]] |volume=3 |issue=3 |pages=257–259 |doi=10.1098/rsbl.2006.0611 |pmid=17389215}}</ref> The classification of birds is a contentious issue. [[Charles Sibley|Sibley]] and [[Jon Ahlquist|Ahlquist]]'s ''Phylogeny and Classification of Birds'' (1990) is a landmark work on the classification of birds,<ref>{{cite book |last=[[Charles Sibley|Sibley]] |first=Charles |coauthors=[[Jon Edward Ahlquist]] |year=1990 |title=Phylogeny and classification of birds |location=New Haven |publisher=Yale University Press |isbn=0-300-04085-7| pages=}}</ref> although it is frequently debated and constantly revised. Most evidence seems to suggest that the assignment of orders is accurate,<ref>{{cite book |last=[[Ernst Mayr|Mayr]] |first=Ernst |coauthors= Short, Lester L.|title= Species Taxa of North American Birds/A Contribution to Comparative Systematics|year=1970 |publisher= Nuttal Orinthological Club|location= Cambridge |oclc=517185}}</ref> but scientists disagree about the relationships between the orders themselves; evidence from modern bird anatomy, fossils and DNA have all been brought to bear on the problem, but no strong consensus has emerged. More recently, new fossil and molecular evidence is providing an increasingly clear picture of the evolution of modern bird orders. ====Modern bird orders==== <!--<div style="align:right; float:right;" border=1>--> {{userboxtop| toptext=&nbsp;}} {{clade |label1=Neornithes&nbsp;&nbsp; |1={{clade |label1=[[Paleognathae]]&nbsp; |1={{clade |1=[[Struthioniformes]] |2=[[Tinamiformes]] }} |label2=&nbsp;[[Neognathae]]&nbsp; |2={{clade |1=Other birds |label1=&nbsp; |label2=[[Galloanserae]]&nbsp; |2={{clade |1=[[Anseriformes]] |2=[[Galliformes]] }} }} }} }} <center><small>Basal divergences of modern birds<br/>based on [[Sibley-Ahlquist taxonomy]]</small></center> <!--</div>--> {{userboxbottom}} This is a list of the taxonomic orders in the subclass Neornithes, or modern birds. This list uses the traditional classification (the so-called [[James Clements|Clements]] order), revised by the Sibley-Monroe classification. The [[list of birds]] gives a more detailed summary of the orders, including families. '''Subclass Neornithes'''<br/> [[Paleognathae]]: * [[Struthioniformes]]—[[ostrich]]es, [[emu]]s, [[kiwi]]s, and allies * [[Tinamiformes]]—tinamous [[Neognathae]]: * [[Anseriformes]]—waterfowl * [[Galliformes]]—fowl * [[Charadriiformes]]—[[gull]]s, [[button-quail]]s, plovers and allies * [[Gaviiformes]]—loons * [[Podicipediformes]]—grebes * [[Procellariiformes]]—[[albatross]]es, [[petrel]]s, and allies * [[Sphenisciformes]]—penguins * [[Pelecaniformes]]—[[pelican]]s and allies * [[Phaethontiformes]]—tropicbirds * [[Ciconiiformes]]—[[stork]]s and allies * [[Cathartiformes]]—New World vultures * [[Phoenicopteriformes]]—flamingos * [[Falconiformes]]—[[falcon]]s, [[eagle]]s, [[hawk]]s and allies * [[Gruiformes]]—[[Crane (bird)|cranes]] and allies * [[Pteroclidiformes]]—sandgrouse * [[Columbiformes]]—[[dove|doves and pigeons]] * [[parrot|Psittaciformes]]—[[parrot]]s and allies * [[Cuculiformes]]—[[cuckoo]]s and [[turaco]]s * [[Opisthocomiformes]]—[[hoatzin]] * [[owl|Strigiformes]]—owls * [[Caprimulgiformes]]—[[nightjar]]s and allies * [[Apodiformes]]—[[swift]]s and [[hummingbird]]s * [[Coraciiformes]]—[[kingfisher]]s and allies * [[Piciformes]]—[[woodpecker]]s and allies * [[Trogoniformes]]—trogons * [[Coliiformes]]—mousebirds * [[Passerine|Passeriformes]]—passerines The radically different Sibley-Monroe classification ([[Sibley-Ahlquist taxonomy]]), based on molecular data, found widespread adoption in a few aspects, as recent molecular, fossil, and anatomical evidence supported the [[Galloanserae]] for example.<ref name = "Ericson"/> ==Distribution== [[Image:House sparrow04.jpg|thumb|left|The range of the [[House Sparrow]] has expanded dramatically due to human activities.<ref>{{cite book |last=Newton |first= Ian|year=2003 |title=The Speciation and Biogeography of Birds |location=Amsterdam |publisher=Academic Press |isbn=0-12-517375-X| pages=p. 463}}</ref> ]] Birds live and breed in most terrestrial habitats and on all seven continents, reaching their southern extreme in the [[Snow Petrel|Snow Petrel's]] breeding colonies up to {{convert|440|km|mi|-1}} inland in [[Antarctica]].<ref>{{cite book |last=Brooke |first=Michael |year=2004 |title=Albatrosses And Petrels Across The World |location=Oxford |publisher= Oxford University Press|isbn=0-19-850125-0| pages=}}</ref> The highest bird [[biodiversity|diversity]] occurs in tropical regions. It was earlier thought that this high diversity was the result of higher [[speciation]] rates in the tropics, however recent studies found higher speciation rates in the high latitudes that were offset by greater [[extinction]] rates than in the tropics.<ref>{{cite journal |last=Weir |first=Jason T. |coauthors=Dolph Schluter |month=March |year=2007 |title=The Latitudinal Gradient in Recent Speciation and Extinction Rates of Birds and Mammals |journal=[[Science (journal)|Science]] |volume=315 |issue=5818 |pages=1574–76 |doi=10.1126/science.1135590 |pmid=17363673}}</ref> Several families of birds have adapted to life both on the world's oceans and in them, with some [[seabird]] species coming ashore only to breed<ref name = "Burger">{{cite book |last=Schreiber |first=Elizabeth Anne |coauthors=Joanna Burger |year=2001 |title=Biology of Marine Birds |location=Boca Raton |publisher=CRC Press |isbn=0-8493-9882-7| pages=}}</ref> and some [[penguin]]s have been recorded diving up to {{convert|300|m|ft|-1}}.<ref>{{cite journal |last=Sato |first=Katsufumi |coauthors=Y. Naito, A. Kato ''et al.'' |month=May |year=2002 |title=Buoyancy and maximal diving depth in penguins: do they control inhaling air volume? |journal=Journal of Experimental Biology |volume=205 |issue=9 |pages=1189–1197 |pmid=11948196 |url=http://jeb.biologists.org/cgi/content/full/205/9/1189}}</ref> Many bird species have established breeding populations in areas to which they have been [[introduced species|introduced]] by humans. Some of these introductions have been deliberate; the [[Ring-necked Pheasant]], for example, has been introduced around the world as a [[game bird]].<ref>{{cite book |last=Hill |first=David |coauthors=Peter Robertson |year=1988 |title=The pheasant: Ecology, Management, and Conservation |location=Oxford |publisher=BSP Professional |isbn=0-632-02011-3| pages=}}</ref> Others have been accidental, such as the establishment of wild [[Monk Parakeet]]s in several North American cities after their escape from captivity.<ref>{{cite web|last=Spreyer |first=Mark F.|coauthors= Enrique H. Bucher| year=1998|title=Monk Parakeet (Myiopsitta monachus)|work=The Birds of North America|publisher=Cornell Lab of Ornithology|url= http://bna.birds.cornell.edu/bna/species/322 |doi=10.2173/bna.322}}</ref> Some species, including [[Cattle Egret]],<ref>{{cite journal |last=Arendt |first=Wayne J. |year=1988 |title=Range Expansion of the Cattle Egret, (''Bubulcus ibis'') in the Greater Caribbean Basin |journal=Colonial Waterbirds |volume=11 |issue=2 |pages=252–62 |doi=10.2307/1521007}}</ref> [[Yellow-headed Caracara]]<ref>{{cite book |last=Bierregaard |first=R.O. |year=1994 |chapter=Yellow-headed Caracara |editor=Josep del Hoyo, Andrew Elliott & Jordi Sargatal (eds.) |title=[[Handbook of the Birds of the World]]. Volume 2; New World Vultures to Guineafowl |location=Barcelona |publisher=Lynx Edicions |isbn=84-87334-15-6| pages=}}</ref> and [[Galah]],<ref>{{cite book |last=Juniper |first=Tony |coauthors=Mike Parr |year=1998 |title=Parrots: A Guide to the Parrots of the World |location=London |publisher=[[Helm Identification Guides|Christopher Helm]] |isbn=0-7136-6933-0| pages=}}</ref> have [[Avian range expansion|spread naturally]] far beyond their original ranges as agricultural practices created suitable new habitat. ==Anatomy== {{main|Bird anatomy}} {{main|Bird vision}} [[Image:Birdmorphology.svg|thumb|300px|right|External anatomy of a bird: 1 Beak, 2 Head, 3 Iris, 4 Pupil, 5 Mantle, 6 Lesser [[covert (feather)|coverts]], 7 Scapulars, 8 Median coverts, 9 Tertials, 10 Rump, 11 Primaries, 12 Vent, 13 Thigh, 14 Tibio-tarsal articulation, 15 Tarsus, 16 Feet, 17 Tibia, 18 Belly, 19 Flanks, 20 Breast, 21 Throat, 22 Wattle]] {{Spoken Wikipedia|Bird_(Anatomy).ogg|2008-01-05}} Compared with other vertebrates, birds have a [[body plan]] that shows many unusual adaptations, mostly to facilitate [[bird flight|flight]]. The skeleton consists of very lightweight bones. They have large air-filled cavities (called pneumatic cavities) which connect with the [[respiratory system]].<ref>{{cite web |last=Ehrlich |first=Paul R. |coauthors=David S. Dobkin, and Darryl Wheye |title=Adaptations for Flight |url=http://www.stanford.edu/group/stanfordbirds/text/essays/Adaptations.html |date=1988 |work=Birds of Stanford |publisher=[[Stanford University]] |accessdate=2007-12-13}} Based on The Birder's Handbook (Paul Ehrlich, David Dobkin, and Darryl Wheye. 1988. Simon and Schuster, New York.)</ref> The skull bones are fused and do not show [[cranial sutures]].<ref name = "Gill">{{cite book |last=Gill |first=Frank |year=1995 |title=Ornithology |publisher=WH Freeman and Co |location=New York |isbn=0-7167-2415-4 |pages=}}</ref> The [[orbit (anatomy)|orbits]] are large and separated by a bony [[septum]]. The [[vertebral column|spine]] has cervical, thoracic, lumbar and caudal regions with the number of cervical (neck) vertebrae highly variable and especially flexible, but movement is reduced in the anterior thoracic vertebrae and absent in the later vertebrae.<ref>{{cite news |title=The Avian Skeleton |url=http://www.paulnoll.com/Oregon/Birds/Avian-Skeleton.html |work=paulnoll.com |accessdate=2007-12-13}}</ref> The last few are fused with the [[pelvis]] to form the [[synsacrum]].<ref name = "Gill"/> The ribs are flattened and the [[sternum]] is keeled for the attachment of flight muscles except in the flightless bird orders. The forelimbs are modified into wings.<ref>{{cite news |title=Skeleton of a typical bird |url=http://fsc.fernbank.edu/Birding/skeleton.htm |date= |work=Fernbank Science Center's Ornithology Web |accessdate=2007-12-13}}</ref> Like the [[reptile]]s, birds are primarily uricotelic, that is, their [[kidney]]s extract nitrogenous wastes from their bloodstream and excrete it as [[uric acid]] instead of [[urea]] or [[ammonia]]. Uric acid is excreted along with feces as a semisolid waste since birds do not have a separate bladder or uretral opening.<ref>{{cite web |last=Ehrlich |first=Paul R. |coauthors=David S. Dobkin, and Darryl Wheye |title=Drinking |url=http://www.stanford.edu/group/stanfordbirds/text/essays/Drinking.html |date=1988 |work=Birds of Stanford |publisher=Standford University |accessdate=2007-12-13}}</ref><ref>{{cite journal |last=Tsahar |first= Ella|coauthors= Carlos Martínez del Rio, Ido Izhaki and Zeev Arad |title=Can birds be ammonotelic? Nitrogen balance and excretion in two frugivores |journal=Journal of Experimental Biology |volume=208 |issue=6 |pages=1025–34 |year=2005 |pmid=15767304 |doi=10.1242/jeb.01495 }}</ref> However, birds such as hummingbirds can be facultatively ammonotelic, excreting most of the nitrogenous wastes as ammonia.<ref>{{cite journal |last=Preest |first=Marion R. |coauthors=Carol A. Beuchat |month=April |year=1997 |title=Ammonia excretion by hummingbirds |journal=Nature |volume=386 |issue= |pages=561–62 |doi=10.1038/386561a0}}</ref> They also excrete [[creatine]], rather than [[creatinine]] like mammals.<ref name = "Gill"/> This material, as well as the output of the intestines, emerges from the bird's [[cloaca]].<ref>{{cite journal |last=Mora |first=J. |coauthors=J. Martuscelli, Juana Ortiz-Pineda, and G. Soberón |year=1965 |title=The Regulation of Urea-Biosynthesis Enzymes in Vertebrates |journal=[[Biochemical Journal]] |volume=96 |pages=28–35 |pmid=14343146 |url= http://www.biochemj.org/bj/096/0028/0960028.pdf}}</ref><ref>{{cite journal |last=Packard |first=Gary C.|year=1966 |title=The Influence of Ambient Temperature and Aridity on Modes of Reproduction and Excretion of Amniote Vertebrates |journal=[[The American Naturalist]] |volume=100 |issue=916 |pages=667–82 |url=http://links.jstor.org/sici?sici=0003-0147(196611/12)100:916%3C667:TIOATA%3E2.0.CO;2-T |doi=10.1086/282459}}</ref> The cloaca is a multi-purpose opening: waste is expelled through it, birds mate by [[Bird anatomy#Reproduction|joining cloaca]], and females lay eggs from it. In addition, many species of birds regurgitate [[Pellet (ornithology)|pellets]].<ref>{{cite journal |last=Balgooyen |first=Thomas G. |year=1971 |title=Pellet Regurgitation by Captive Sparrow Hawks (''Falco sparverius'') |journal=[[Condor (journal)|Condor]] |volume=73 |issue=3 |pages=382–85 |doi=10.2307/1365774 |url=http://elibrary.unm.edu/sora/Condor/files/issues/v073n03/p0382-p0385.pdf}}</ref> The [[digestive system]] of birds is unique, with a [[crop (anatomy)|crop]] for storage and a [[gizzard]] that contains swallowed stones for grinding food to compensate for the lack of teeth.<ref>{{cite journal |last=Gionfriddo |first=James P. |coauthors= Louis B. Best |month=February |year=1995 |title=Grit Use by House Sparrows: Effects of Diet and Grit Size |journal=Condor |volume=97 |issue=1 |pages=57–67 |doi=10.2307/1368983 |url=http://elibrary.unm.edu/sora/Condor/files/issues/v097n01/p0057-p0067.pdf}}</ref> Most birds are highly adapted for rapid digestion to aid with flight.<ref name = Attenborough">{{cite book |last=Attenborough |first=David |authorlink=David Attenborough |year=1998 |title=[[The Life of Birds]] |location=Princeton |publisher=Princeton University Press |isbn=0-691-01633-X| pages=}}</ref> Some migratory birds have the additional ability to reduce parts of the intestines prior to migration.<ref name = "Battley">{{cite journal |last=Battley |first=Phil F. |coauthors=Theunis Piersma, Maurine W. Dietz ''et als.'' |month=January |year=2000 |title=Empirical evidence for differential organ reductions during trans-oceanic bird flight |journal=[[Proceedings of the Royal Society]] B |volume=267 |issue=1439 |pages=191–5 |doi=10.1098/rspb.2000.0986 |pmid=10687826}} (Erratum in ''Proceedings of the Royal Society B'' '''267'''(1461):2567.)</ref> Birds have one of the most complex [[respiratory system]]s of all animal groups.<ref name = "Gill"/> Upon inhalation, 75% of the fresh air bypasses the lungs and flows directly into a posterior [[Bird anatomy#Respiratory system|air sac]] which extends from the lungs and connects with air spaces in the bones and fills them with air. The other 25% of the air goes directly into the lungs. When the bird exhales, the used air flows out of the lung and the stored fresh air from the posterior air sac is simultaneously forced into the lungs. Thus, a bird's lungs receive a constant supply of fresh air during both inhalation and exhalation.<ref>{{cite journal |last=Maina |first=John N. |month=November |year=2006 |title=Development, structure, and function of a novel respiratory organ, the lung-air sac system of birds: to go where no other vertebrate has gone |journal=Biological Reviews |volume=81 |issue=4 |pages=545–79 |doi=10.1111/j.1469-185X.2006.tb00218.x |pmid=17038201 |doi_brokendate=2008-06-28}}</ref> Sound production is achieved using the [[syrinx (biology)|syrinx]], a muscular chamber with several tympanic membranes which is situated at the lower end of the trachea, from where it separates.<ref name = "Suthers">{{cite book |last=Suthers |first=Roderick A. |coauthors=Sue Anne Zollinger |chapter=Producing song: the vocal apparatus |editor=H. Philip Zeigler & Peter Marler (eds.) |year=2004 |title=Behavioral Neurobiology of Birdsong |series=Annals of the New York Academy of Sciences '''1016''' |location=New York |publisher=New York Academy of Sciences |isbn=1-57331-473-0 |pages=109-129 |doi=10.1196/annals.1298.041}} PMID 15313772</ref> The bird's heart has four chambers and the right aortic arch gives rise to [[systemic circulation]] (unlike in the mammals where the left arch is involved).<ref name = "Gill"/> The postcava receives blood from the limbs via the renal portal system. Unlike in mammals, the [[red blood cells]] in birds have a [[cell nucleus|nucleus]].<ref>{{cite journal |last=Scott |first=Robert B. |month=March |year=1966 |title=Comparative hematology: The phylogeny of the erythrocyte |journal=Annals of Hematology |volume=12 |issue=6 |pages=340–51 |doi=10.1007/BF01632827 |pmid=5325853}}</ref> The [[nervous system]] is large relative to the bird's size.<ref name = "Gill"/> The most developed part of the brain is the one that controls the flight-related functions, while the [[cerebellum]] coordinates movement and the [[cerebrum]] controls behaviour patterns, navigation, mating and nest building. Most birds have a poor [[olfaction|sense of smell]] with notable exceptions including [[kiwi]]s,<ref>{{cite journal |last=Sales |first=James |year=2005 |title=The endangered kiwi: a review |journal=Folia Zoologica |volume=54 |issue=1–2 |pages=1–20 |url=http://www.ivb.cz/folia/54/1-2/01-20.pdf}}</ref> [[New World vulture]]s<ref name="Avian Sense of Smell">{{cite web |last=Ehrlich |first=Paul R. |coauthors=David S. Dobkin, and Darryl Wheye |title=The Avian Sense of Smell |url=http://www.stanford.edu/group/stanfordbirds/text/essays/Avian_Sense.html |date=1988 |work=Birds of Stanford |publisher=Standford University |accessdate=2007-12-13}}</ref> and [[tubenoses]].<ref>{{cite journal |last=Lequette |first=Benoit |coauthors=Christophe Verheyden, Pierre Jouventin |month=August |year=1989 |title=Olfaction in Subantarctic seabirds: Its phylogenetic and ecological significance |journal=The Condor |volume=91 |issue=3 |pages=732–35 |doi=10.2307/1368131 |url=http://elibrary.unm.edu/sora/Condor/files/issues/v091n03/p0732-p0735.pdf}}</ref> The avian [[visual system]] is usually highly developed. Water birds have special flexible lenses, allowing accommodation for vision in air and water.<ref name = "Gill"/> Some species also have dual [[fovea]]. Birds are [[tetrachromacy|tetrachromatic]], possessing [[ultraviolet]] (UV) sensitive [[cone cell]]s in the eye as well as green, red and blue ones.<ref>{{cite journal |last=Wilkie |first=Susan E. |coauthors=Peter M. A. M. VISSERS, Debipriya DAS ''et als.'' |year=1998 |title=The molecular basis for UV vision in birds: spectral characteristics, cDNA sequence and retinal localization of the UV-sensitive visual pigment of the budgerigar (''Melopsittacus undulatus'') |journal=[[Biochemical Journal]] |volume=330 |pages=541–47 |pmid=9461554}}</ref> This allows them to perceive ultraviolet light, which is involved in courtship. Many birds show plumage patterns in ultraviolet that are invisible to the human eye; some birds whose sexes appear similar to the naked eye are distinguished by the presence of [[ultraviolet]] reflective patches on their feathers. Male [[Blue Tit]]s have an ultraviolet reflective crown patch which is displayed in courtship by posturing and raising of their nape feathers.<ref>{{cite journal |last=Andersson|first= S.|coathors=J. Ornborg & M. Andersson |title=Ultraviolet sexual dimorphism and assortative mating in blue tits|journal=Proceeding of the Royal Society B |year=1998 |volume=265 |issue=1395 |pages=445–50 |doi=10.1098/rspb.1998.0315}}</ref> Ultraviolet light is also used in foraging—[[kestrel]]s have been shown to search for prey by detecting the UV reflective urine trail marks left on the ground by rodents.<ref>{{cite journal |last=Viitala |first= Jussi |coauthors=Erkki Korplmäki, Pälvl Palokangas & Minna Koivula |year=1995 |journal=Nature |volume=373 |issue=6513 |pages=425–27 |title=Attraction of kestrels to vole scent marks visible in ultraviolet light |doi=10.1038/373425a0}}</ref> The eyelids of a bird are not used in blinking. Instead the eye is lubricated by the [[nictitating membrane]], a third eyelid that moves horizontally.<ref>{{cite journal |last=Williams |first=David L. |coauthors=Edmund Flach |month=March |year=2003 |title=Symblepharon with aberrant protrusion of the nictitating membrane in the snowy owl (''Nyctea scandiaca'') |journal=Veterinary Ophthalmology |volume=6 |issue=1 |pages=11–13 |doi=10.1046/j.1463-5224.2003.00250.x |pmid=12641836}}</ref> The nictitating membrane also covers the eye and acts as a [[contact lens]] in many aquatic birds.<ref name = "Gill"/> The bird [[retina]] has a fan shaped blood supply system called the [[Pecten oculi|pecten]].<ref name = "Gill"/> Most birds cannot move their eyes, although there are exceptions, such as the [[Great Cormorant]].<ref>{{cite journal |last=White |first=Craig R. |coauthors=Norman Day, Patrick J. Butler, Graham R. Martin |month=July |year=2007 |title=Vision and Foraging in Cormorants: More like Herons than Hawks? |journal=PLoS ONE |volume=2 |issue=7 |pages=e639 |doi=10.1371/journal.pone.0000639 |pmid=17653266}}</ref> Birds with eyes on the sides of their heads have a wide [[visual field]], while birds with eyes on the front of their heads, such as owls, have [[binocular vision]] and can estimate the depth of field.<ref>{{cite journal |last=Martin |first= Graham R. |coauthors=Gadi Katzir |year=1999 |title=Visual fields in short-toed eagles, ''Circaetus gallicus'' (Accipitridae), and the function of binocularity in birds |journal=Brain, Behaviour and Evolution |volume=53 |issue=2 |pages=55–66 |doi=10.1159/000006582 |pmid= 9933782}}</ref> The avian [[ear]] lacks external [[pinna (anatomy)|pinnae]] but is covered by feathers, although in some birds, such as the ''[[Asio]]'', ''[[Horned owl|Bubo]]'' and ''[[Scops owl|Otus]]'' [[owl]]s, these feathers form tufts which resemble ears. The inner ear has a [[cochlea]], but it is not spiral as in mammals.<ref>{{cite journal |last=Saito |first=Nozomu |year=1978 |title=Physiology and anatomy of avian ear |journal=The Journal of the Acoustical Society of America |volume=64 |issue=S1 |pages=S3 |doi=10.1121/1.2004193}}</ref> A few species are able to use chemical defenses against predators; some [[Procellariiformes]] can eject an unpleasant [[stomach oil|oil]] against an aggressor,<ref>{{cite journal |last=Warham |first=John |year=1977 |title=The Incidence, Function and ecological significance of petrel stomach oils |journal=Proceedings of the New Zealand Ecological Society |volume=24 |pages=84–93 |url=http://www.newzealandecology.org/nzje/free_issues/ProNZES24_84.pdf |doi=10.2307/1365556}}</ref> and some species of [[pitohui]]s from [[New Guinea]] secrete a powerful [[neurotoxin]] in their skin and feathers.<ref>{{cite journal |last=Dumbacher |first=J.P. |coauthors=B.M. Beehler, T.F. Spande ''et als.'' |month=October |year=1992 |title=omobatrachotoxin in the genus ''Pitohui'': chemical defense in birds? |journal=Science |volume=258 |issue=5083 |pages=799–801 |doi=10.1126/science.1439786 |pmid=1439786}}</ref> Birds have two sexes: male and female. Birds' sex is determined by [[ZW sex-determination system|Z and W sex chromosomes]], rather than the X and Y chromosomes seen in mammals. Males carry two Z chromosomes (ZZ), and females carry a W chromosome and a Z chromosome (WZ).<ref name = "Gill"/> In nearly all species, an individual's sex is determined at fertilization. However, one recent study demonstrated [[temperature-dependent sex determination]] among [[Australian Brush-turkeys]], for which higher temperatures during incubation resulted in a higher female-to-male sex ratio.<ref>{{cite journal|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= 278–85|doi= 10.1111/j.1442-9993.2007.01709.x}}</ref> ===Feathers and plumage=== {{main|Feather|Flight feather}} [[Image:African Scops owl.jpg|thumb|left|The plumage of the [[African Scops Owl]] allows it to blend in with its surroundings.]] [[Feather]]s are a feature unique to birds. They facilitate [[bird flight|flight]], provide insulation that aids in [[thermoregulation]], and are used in display, camouflage, and signaling.<ref name ="Gill"/> There are several types of feathers, each serving its own set of purposes. Feathers are epidermal growths attached to the skin and arise only in specific tracts of skin called pterylae. The distribution pattern of these feather tracts (pterylosis) is used in taxonomy and systematics. The arrangement and appearance of feathers on the body, called [[plumage]], may vary within species by age, social status,<ref>{{cite journal |last=Belthoff |first=James R. |coauthors=Alfred M. Dufty, Jr., Sidney A. Gauthreaux, Jr. |month=August |year=1994 |title=Plumage Variation, Plasma Steroids and Social Dominance in Male House Finches |journal=The Condor |volume=96 |issue=3 |pages=614–25 |doi=10.2307/1369464}}</ref> and [[sexual dimorphism|sex]].<ref>{{cite web|last=Guthrie| firt=R. Dale|title=How We Use and Show Our Social Organs |work=Body Hot Spots: The Anatomy of Human Social Organs and Behavior |url=http://employees.csbsju.edu/lmealey/hotspots/chapter03.htm |accessdate=2007-10-19}}</ref> Plumage is regularly [[moult]]ed; the standard plumage of a bird that has moulted after breeding is known as the "non-breeding" plumage, or – in the [[Humphrey-Parkes terminology]] – "basic" plumage; breeding plumages or variations of the basic plumage are known under the Humphrey-Parkes system as "alternate" plumages.<ref>{{cite journal |last=Humphrey |first=Philip S. |coauthors=Kenneth C. Parkes |year=1959 |title=An approach to the study of molts and plumages |journal=The Auk |volume=76 |pages=1–31 |url=http://elibrary.unm.edu/sora/Auk/v076n01/p0001-p0031.pdf |doi=10.2307/3677029}}</ref> Moulting is annual in most species, although some may have two moults a year, and large birds of prey may moult only once every few years. Moulting patterns vary across species. Some drop and regrow wing [[flight feather]]s, starting sequentially from the outermost feathers and progressing inwards (centripetal), while others replace feathers starting from the innermost ones (centrifugal). A small number of species, such as ducks and geese, lose all of their flight feathers at once, temporarily becoming flightless.<ref name=debeeretal>de Beer SJ, Lockwood GM, Raijmakers JHFS, Raijmakers JMH, Scott WA, Oschadleus HD, Underhill LG (2001). [http://web.uct.ac.za/depts/stats/adu/ringmanual.htm SAFRING Bird Ringing Manual.] SAFRING.</ref> Centripetal moults of tail feathers are seen for example in the [[Phasianidae]].<ref>{{cite journal |last= Gargallo|first= Gabriel|year= 1994|month= |title=Flight Feather Moult in the Red-Necked Nightjar ''Caprimulgus ruficollis'' |journal=Journal of Avian Biology |volume= 25|issue= 2|pages= 119–24 |doi=10.2307/3677029}}</ref> Centrifugal moult is seen, for instance, in the tail feathers of [[woodpecker]]s and [[treecreeper]]s, although it begins with the second innermost pair of tail-feathers and finishes with the central pair of feathers so that the bird maintains a functional climbing tail.<ref>{{cite journal |last=Mayr |first=Ernst |coauthors=Margaret Mayr |year= 1954|title=The tail molt of small owls |journal=The Auk |volume=71 |issue=2 |pages=172–78 |url=http://elibrary.unm.edu/sora/Auk/v071n02/p0172-p0178.pdf|doi=10.1086/515854|doi_brokendate=2008-06-28}}</ref> The general pattern seen in [[passerine]]s is that the primaries are replaced outward, secondaries inward, and the tail from center outward.<ref>{{cite web| first=Robert B.|last= Payne|title=Birds of the World, Biology 532|url=http://www.ummz.umich.edu/birds/resources/families_otw.html|publiher=Bird Division, University of Michigan Museum of Zoology|accessdate=2007-10-20}}</ref> Before nesting, the females of most bird species gain a bare [[brood patch]] by losing feathers close to the belly. The skin there is well supplied with blood vessels and helps the bird in incubation.<ref>{{cite journal |last=Turner |first=J. Scott |year=1997 |title=On the thermal capacity of a bird's egg warmed by a brood patch |journal=Physiological Zoology |volume=70 |issue=4 |pages=470–80 |doi=10.1086/515854 |pmid=9237308 |doi_brokendate=2008-06-28}}</ref> Feathers require maintenance and birds preen or groom them daily, spending an average of around 9% of their daily time on this.<ref>{{cite journal |last=Walther |first=Bruno A. |coauthors=Dale H. Clayton |year=2005 |title=Elaborate ornaments are costly to maintain: evidence for high maintenance handicaps |journal=Behavioural Ecology |volume=16 |issue=1 |pages=89–95 |doi=10.1093/beheco/arh135}}</ref> The bill is used to brush away foreign particles and to apply [[wax]]y secretions from the [[uropygial gland]]; these secretions protect the feathers' flexibility and act as an antimicrobial agent, inhibiting the growth of feather-degrading [[bacteria]].<ref>{{cite journal |last=Shawkey |first=Matthew D. |coauthors=Shawkey, Shreekumar R. Pillai, Geoffrey E. Hill |year=2003 |title=Chemical warfare? Effects of uropygial oil on feather-degrading bacteria |journal=[[Journal of Avian Biology]] |volume=34 |issue=4 |pages=345–49 |doi=10.1111/j.0908-8857.2003.03193.x}}</ref> This may be supplemented with the secretions of [[formic acid]] from ants, which birds receive through a behaviour known as [[Anting (bird activity)|anting]], to remove feather parasites.<ref>{{cite journal |last=Ehrlich |first=Paul R. |coauthors=David S. Dobkin, Darryl Wheye |year=1986 |title=The Adaptive Significance of Anting |journal=The Auk |volume=103 |issue=4 |pages=835 |url=http://elibrary.unm.edu/sora/Auk/v103n04/p0835-p0835.pdf}}</ref> ===Scales=== The scales of birds are composed of the same keratin as beaks, claws, and spurs. They are found mainly on the toes and [[metatarsus]], but may be found further up on the ankle in some birds. Most bird scales do not overlap significantly, except in the cases of [[kingfisher]]s and [[woodpecker]]s. Bird embryos begin development with smooth skin. On the feet, the [[stratum corneum|corneum]], or outermost layer, of this skin may keratinize, thicken and form scales. These ''scales'' can be organized into; # Cancella - minute scales which are really just a thickening and hardening of the skin, crisscrossed with shallow grooves. # Reticula - small but distinct, separate, scales. Found on the [[lateral]] and [[medial]] surfaces (sides) of the chicken [[metatarsus]]. # Scutella - scales that are not quite as large as scutes, such as those found on the [[caudal]], or hind part, of the chicken [[metatarsus]]. # [[Scute]]s - the largest scales, usually on the [[anterior]] surface of the [[metatarsus]] and [[dorsal]] surface of the toes. The rows of scutes on the [[anterior]] of the [[metatarsus]] can be called an acrometatarsium or acrotarsium. Feathers can be intermixed with scales on some birds' feet. Feather follicles can lie between scales or even directly beneath them, in the deeper [[dermis]] layer of the skin. In this last case, feathers may emerge directly through scales, and be encircled at the plane of emergence entirely by the keratin of the scale.<ref>{{cite book |last=Lucas |first=Alfred M. |year= 1972 |title= Avian Anatomy - integument |location=East Lansing, Michigan, USA |publisher=USDA Avian Anatomy Project, Michigan State University |pages= 67, 344, 394-601}}</ref> The scales of birds are thought to be [[Homology (biology)|homologous]] to those of reptiles and mammals<ref>{{cite book |last=Lucas |first=Alfred M. |year= 1972 |title= Avian Anatomy - integument |location=East Lansing, Michigan, USA |publisher=USDA Avian Anatomy Project, Michigan State University |pages= 67, 344, 394-601}}</ref>. ===Flight=== {{main|Bird flight}} [[Image:Restless flycatcher04.jpg|thumb|A [[Restless Flycatcher]] in the downstroke of flapping flight]] Most birds can [[Flying and gliding animals|fly]], which distinguishes them from almost all other vertebrates. Flight is the primary means of locomotion for most bird species and is used for breeding, feeding, and predator avoidance and escape. Birds have various adaptations for flight, including a lightweight skeleton, two large flight muscles (the pectoralis—accounting for 15% of the total mass of the bird—and the supracoracoideus), and a modified forelimb ([[wing]]) that serves as an [[airfoil|aerofoil]].<ref name = "Gill"/> Wing shape and size generally determine a bird species' type of flight; many birds combine powered, flapping flight with less energy-intensive soaring flight. About 60 extant bird species are [[Flightless bird|flightless]], as were many extinct birds.<ref>{{cite book |last=Roots |first=Clive |year=2006 |title=Flightless Birds |location=Westport |publisher=Greenwood Press |isbn=978-0-313-33545-7| pages=}}</ref> Flightlessness often arises in birds on isolated islands, probably due to limited resources and the absence of land predators.<ref>{{cite journal |last=McNab |first=Brian K. |month=October |year=1994 |title=Energy Conservation and the Evolution of Flightlessness in Birds |journal=The American Naturalist |volume=144 |issue=4 |pages=628–42 |url=http://links.jstor.org/sici?sici=0003-0147(199410)144:4%3C628:ECATEO%3E2.0.CO;2-D |doi=10.1086/285697}}</ref> Though flightless, penguins use similar musculature and movements to "fly" through the water, as do [[auk]]s, [[shearwater]]s and [[dipper]]s.<ref>{{cite journal |last=Kovacs |first=Christopher E. |coauthors=Ron A. Meyers |month=May |year=2000 |title=Anatomy and histochemistry of flight muscles in a wing-propelled diving bird, the Atlantic Puffin, ''Fratercula arctica'' |journal=Journal of Morphology |volume=244 |issue=2 |pages=109–25|doi=10.1002/(SICI)1097-4687(200005)244:2<br><109::AID-JMOR2>3.0.CO;2-0 |doi_brokendate=2008-06-28}}</ref> ==Behaviour== Most birds are [[diurnal animal|diurnal]], but some birds, such as many species of [[owl]]s and [[nightjar]]s, are [[nocturnal]] or [[crepuscular]] (active during twilight hours), and many coastal [[wader]]s feed when the tides are appropriate, by day or night.<ref>{{cite journal |last=Robert |first=Michel |coauthors=Raymond McNeil, Alain Leduc |month=January |year= 1989 |title=Conditions and significance of night feeding in shorebirds and other water birds in a tropical lagoon |journal=The Auk |volume=106 |issue=1 |pages=94–101 |url=http://elibrary.unm.edu/sora/Auk/v106n01/p0094-p0101.pdf}}</ref> ===Diet and feeding=== [[Image:BirdBeaksA.svg|thumb|right|Feeding adaptations in beaks]] Birds' diets are varied and often include [[nectar (plant)|nectar]], fruit, plants, seeds, [[carrion]], and various small animals, including other birds.<ref name = "Gill"/> Because birds have no teeth, their [[digestive system]] is adapted to process [[mastication|unmasticated]] food items that are swallowed whole. Birds that employ many strategies to obtain food or feed on a variety of food items are called generalists, while others that concentrate time and effort on specific food items or have a single strategy to obtain food are considered specialists.<ref name = "Gill"/> Birds' feeding strategies vary by species. Many birds glean for insects, invertebrates, fruit, or seeds. Some hunt insects by suddenly attacking from a branch. Nectar feeders such as [[hummingbird]]s, [[sunbird]]s, [[lories and lorikeets|lories, and lorikeets]] amongst others have specially adapted brushy tongues and in many cases bills designed to fit co-adapted flowers.<ref>{{cite journal |last=Paton |first=D. C. |coauthors=B. G. Collins |year=1989 |title=Bills and tongues of nectar-feeding birds: A review of morphology, function, and performance, with intercontinental comparisons |journal=Australian Journal of Ecology |volume=14 |issue=4 |pages=473–506 |doi=10.2307/1942194 }}</ref> [[Kiwi]]s and [[shorebird]]s with long bills probe for invertebrates; shorebirds' varied bill lengths and feeding methods result in the separation of [[ecological niche]]s.<ref name = "Gill"/><ref>{{cite journal |last=Baker |first=Myron Charles |coauthors=Ann Eileen Miller Baker |year=1973 |title=Niche Relationships Among Six Species of Shorebirds on Their Wintering and Breeding Ranges |journal=Ecological Monographs |volume=43 |issue=2 |pages=193–212 |doi=10.2307/1942194}}</ref> [[Loon]]s, [[diving duck]]s, [[penguin]]s and [[auks]] pursue their prey underwater, using their wings or feet for propulsion,<ref name = "Burger"/> while aerial predators such as [[sulidae|sulid]]s, [[kingfisher]]s and [[tern]]s plunge dive after their prey. [[Flamingo]]s, three species of [[prion (bird)|prion]], and some ducks are [[filter feeder]]s.<ref>{{cite journal |last=Cherel |first=Yves |coauthors=Pierrick Bocher, Claude De Broyer ''et als.'' |month= |year=2002 |title=Food and feeding ecology of the sympatric thin-billed ''Pachyptila belcheri'' and Antarctic ''P. desolata'' prions at Iles Kerguelen, Southern Indian Ocean |journal=Marine Ecology Progress Series |volume=228 |pages=263–81 |doi=10.3354/meps228263}}</ref><ref>{{cite journal |last=Jenkin |first=Penelope M. |year=1957 |title=The Filter-Feeding and Food of Flamingoes (Phoenicopteri). |journal=Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences |volume=240 |issue=674 |pages=401–93 |url=http://links.jstor.org/sici?sici=0080-4622(19570509)240:674%3C401:TFAFOF%3E2.0.CO;2-E |doi=10.1098/rstb.1957.0004}}</ref> [[Geese]] and [[dabbling duck]]s are primarily grazers. Some species, including [[frigatebird]]s, [[gull]]s,<ref>{{cite journal |last=Miyazaki |first=Masamine |month=July |year=1996 |title=Vegetation cover, kleptoparasitism by diurnal gulls and timing of arrival of nocturnal Rhinoceros Auklets |journal=The Auk |volume=113 |issue=3 |pages=698–702 |doi= 10.2307/3677021 |url=http://elibrary.unm.edu/sora/Auk/v113n03/p0698-p0702.pdf}}</ref> and [[skua]]s,<ref>{{cite journal |last=Bélisle |first=Marc |coauthors=Jean-François Giroux |month=August |year=1995 |title=Predation and kleptoparasitism by migrating Parasitic Jaegers |journal=The Condor |volume=97 |issue=3 |pages= 771–781 |doi=10.2307/1369185 |url=http://elibrary.unm.edu/sora/Condor/files/issues/v097n03/p0771-p0781.pdf}}</ref> engage in [[kleptoparasitism]], stealing food items from other birds. Kleptoparasitism is thought to be a supplement to food obtained by hunting, rather than a significant part of any species' diet; a study of [[Great Frigatebird]]s stealing from [[Masked Booby|Masked Boobies]] estimated that the frigatebirds stole at most 40% of their food and on average stole only 5%.<ref>{{cite journal |last=Vickery |first=J. A. |coauthors=M. De L. Brooke |month=May |year=1994 |title=The Kleptoparasitic Interactions between Great Frigatebirds and Masked Boobies on Henderson Island, South Pacific |journal=The Condor |volume=96 |issue=2 |pages=331–40 |doi=10.2307/1369318 |url= http://elibrary.unm.edu/sora/Condor/files/issues/v096n02/p0331-p0340.pdf}}</ref> Other birds are [[scavenger]]s; some of these, like [[vulture]]s, are specialised carrion eaters, while others, like gulls, [[corvid]]s, or other birds of prey, are opportunists.<ref>{{cite journal |last=Hiraldo |first=F.C. |coauthors= J.C. Blanco and J. Bustamante |year=1991 |title=Unspecialized exploitation of small carcasses by birds |journal=Bird Studies |volume=38 |issue=3 |pages=200–07 |doi=10.1007/s10646-008-0193-1.<p> |doi_brokendate=2008-06-28}}</ref> ===Migration=== {{main|Bird migration}} Many bird species migrate to take advantage of global differences of [[season]]al temperatures, therefore optimising availability of food sources and breeding habitat. These migrations vary among the different groups. Many landbirds, [[shorebird]]s, and [[waterbird]]s undertake annual long distance migrations, usually triggered by the length of daylight as well as weather conditions. These birds are characterised by a breeding season spent in the [[temperate]] or [[arctic]]/[[antarctic]] regions and a non-breeding season in the [[tropical]] regions or opposite hemisphere. Before migration, birds substantially increase body fats and reserves and reduce the size of some of their organs.<ref name = "Klaassen">{{cite journal |last=Klaassen |first=Marc |coauthors= |month= |year=1996 |title=Metabolic constraints on long-distance migration in birds |journal=Journal of Experimental Biology |volume=199 |issue=1 |pages=57–64 |pmid=9317335 |url=http://jeb.biologists.org/cgi/reprint/199/1/57}} </ref><ref name = "Battley"/> Migration is highly demanding energetically, particularly as birds need to cross deserts and oceans without refuelling. Landbirds have a flight range of around {{convert|2500|km|mi|-2|abbr=on}} and shorebirds can fly up to {{convert|4000|km|mi|-2|abbr=on}},<ref name = "Gill">{{cite book |last=Gill |first=Frank |year=1995 |title=Ornithology |edition=2nd edition |location=New York |publisher=W.H. Freeman |isbn=0-7167-2415-4| pages=}}</ref> although the [[Bar-tailed Godwit]] is capable of non-stop flights of up to {{convert|10200|km|mi|-2|abbr=on}}.<ref>{{cite news |title= Long-distance Godwit sets new record |url=http://www.birdlife.org/news/news/2007/04/bar-tailed_godwit_journey.html |date= 05-04-2007 |publisher=[[BirdLife International]] |accessdate=2007-12-13}}</ref> [[Seabird]]s also undertake long migrations, the longest annual migration being those of [[Sooty Shearwater]]s, which nest in [[New Zealand]] and [[Chile]] and spend the northern summer feeding in the North Pacific off [[Japan]], [[Alaska]] and [[California]], an annual round trip of {{convert|64000|km|mi|-2|abbr=on}}.<ref>{{cite journal |last=Shaffer |first=Scott A. |coauthors=Yann Tremblay, Henri Weimerskirch ''et als'' |year=2006 |title=Migratory shearwaters integrate oceanic resources across the Pacific Ocean in an endless summer |journal=Proceedings of the National Academy of Sciences |volume=103 |issue=34 |pages=12799–802 |doi=10.1073/pnas.0603715103 |pmid= 16908846}}</ref> Other seabirds disperse after breeding, travelling widely but having no set migration route. Albatrosses nesting in the Southern Ocean often undertake circumpolar trips between breeding seasons.<ref>{{cite journal |last=Croxall |first=John P. |coauthors=Janet R. D. Silk, Richard A. Phillips ''et als.'' |year=2005 |title=Global Circumnavigations: Tracking year-round ranges of nonbreeding Albatrosses |journal=Science |volume=307 |issue=5707 |pages=249–50 |doi=10.1126/science.1106042 |pmid=15653503}}</ref> [[Image:Bar-tailed Godwit migration.jpg|thumb|left|The routes of satellite tagged [[Bar-tailed Godwit]]s migrating north from [[New Zealand]]. This species has the longest known non-stop migration of any species, up to {{convert|10200|km|mi|-2|abbr=on}}.]] Some bird species undertake shorter migrations, travelling only as far as is required to avoid bad weather or obtain food. [[wiktionary:irruptive|Irruptive]] species such as the boreal [[finch]]es are one such group and can commonly be found at a location in one year and absent the next. This type of migration is normally associated with food availability.<ref>{{cite journal |last=Wilson |first=W. Herbert, Jr. |year=1999 |title=Bird feeding and irruptions of northern finches:are migrations short stopped? |journal=North America Bird Bander |volume=24 |issue= 4|pages=113–21 |url=http://elibrary.unm.edu/sora/NABB/v024n04/p0113-p0121.pdf}}</ref> Species may also travel shorter distances over part of their range, with individuals from higher latitudes travelling into the existing range of conspecifics; others undertake partial migrations, where only a fraction of the population, usually females and subdominant males, migrates.<ref>{{cite journal |last=Nilsson |first=Anna L. K. |coauthors=Thomas Alerstam, and Jan-Åke Nilsson |year=2006 |title=Do partial and regular migrants differ in their responses to weather? |journal=The Auk |volume=123 |issue=2 |pages=537–47 |url=http://findarticles.com/p/articles/mi_qa3793/is_200604/ai_n16410121|doi=10.1642/0004-8038(2006)123[537:DPARMD]2.0.CO;2}}</ref> Partial migration can form a large percentage of the migration behaviour of birds in some regions; in Australia, surveys found that 44% of non-passerine birds and 32% of passerines were partially migratory.<ref>{{cite journal |last=Chan |first=Ken |year=2001 |title=Partial migration in Australian landbirds: a review |journal=[[Emu (journal)|Emu]] |volume=101 |issue=4 |pages=281–92 |doi=10.1071/MU00034}}</ref> Altitudinal migration is a form of short distance migration in which birds spend the breeding season at higher altitudes elevations and move to lower ones during suboptimal conditions. It is most often triggered by temperature changes and usually occurs when the normal territories also become inhospitable due to lack of food.<ref>{{cite journal |last=Rabenold |first=Kerry N. |coauthors=Patricia Parker Rabenold |year=1985 |title=Variation in Altitudinal Migration, Winter Segregation, and Site Tenacity in two subspecies of Dark-eyed Juncos in the southern Appalachians |journal= The Auk|volume=102 |issue=4 |pages=805–19 |url=http://elibrary.unm.edu/sora/Auk/v102n04/p0805-p0819.pdf}}</ref> Some species may also be nomadic, holding no fixed territory and moving according to weather and food availability. [[True parrots|Parrot]]s as a [[family (biology)|family]] are overwhelmingly neither migratory nor sedentary but considered to either be dispersive, irruptive, nomadic or undertake small and irregular migrations.<ref>{{cite book |last=Collar |first=Nigel J. |year= 1997|chapter=Family Psittacidae (Parrots)|title=[[Handbook of the Birds of the World]], Volume 4: Sandgrouse to Cuckoos |editor=Josep del Hoyo, Andrew Elliott & Jordi Sargatal (eds.) |location=Barcelona |publisher=Lynx Edicions |isbn=84-87334-22-9| pages=}}</ref> The ability of birds to return to precise locations across vast distances has been known for some time; in an experiment conducted in the 1950s a [[Manx Shearwater]] released in [[Boston, Massachusetts|Boston]] returned to its colony in [[Skomer]], [[Wales]] within 13 days, a distance of {{convert|5150|km|mi|-2|abbr=on}}.<ref>{{cite journal |last=Matthews |first=G. V. T. |year=1953 |title=Navigation in the Manx Shearwater |journal=Journal of Experimental Biology |volume=30 |issue=2 |pages=370–96 |url=http://jeb.biologists.org/cgi/reprint/30/3/370}}</ref> Birds navigate during migration using a variety of methods. For [[diurnal animal|diurnal]] migrants, the [[sun]] is used to navigate by day, and a stellar compass is used at night. Birds that use the sun compensate for the changing position of the sun during the day by the use of an [[Chronobiology|internal clock]].<ref name = "Gill"/> Orientation with the stellar compass depends on the position of the [[constellation]]s surrounding [[Polaris]].<ref>{{cite journal |last=Mouritsen |first=Henrik |coauthors=Ole Næsbye Larsen |year=2001 |title=Migrating songbirds tested in computer-controlled Emlen funnels use stellar cues for a time-independent compass |journal=Journal of Experimental Biology |volume=204 |issue=8 |pages=3855–65 |pmid= 11807103 |url=http://jeb.biologists.org/cgi/content/full/204/22/3855}}</ref> These are backed up in some species by their ability to sense the Earth's [[geomagnetism]] through specialised [[Photoreceptor cell|photoreceptor]]s.<ref>{{cite journal |last=Deutschlander |first=Mark E. |coauthors=John B. Phillips and S. Chris Borland |year=1999 |title=The case for light-dependent magnetic orientation in animals |journal=Journal of Experimental Biology |volume=202 |issue=8 |pages=891–908 |pmid= 10085262 |url=http://jeb.biologists.org/cgi/reprint/202/8/891}}</ref> ===Communication=== [[Image:Stavenn Eurypiga helias 00.jpg|thumb|right|The startling display of the [[Sunbittern]] mimics a large predator.]] Birds [[Animal communication|communicate]] using primarily visual and auditory signals. Signals can be interspecific (between species) and intraspecific (within species). Birds sometimes use plumage to assess and assert social dominance,<ref>{{cite journal |last=Möller |first=Anders Pape |year=1988 |title= Badge size in the house sparrow ''Passer domesticus''|journal=Behavioral Ecology and Sociobiology |volume=22 |issue=5 |pages=373–78 |doi=10.1007/BF00295107 |doi_brokendate= 2008-06-28}}</ref> to display breeding condition in sexually selected species, or to make threatening displays, as in the [[Sunbittern]]'s mimicry of a large predator to ward off [[hawk]]s and protect young chicks.<ref>{{cite journal |last=Thomas |first=Betsy Trent |coauthors=Stuart D. Strahl |month= |year=1990 |title=Nesting Behavior of Sunbitterns (''Eurypyga helias'') in Venezuela |journal=The Condor |volume=92 |issue=3 |pages=576–81 |doi=10.2307/1368675 |url=http://elibrary.unm.edu/sora/Condor/files/issues/v092n03/p0576-p0581.pdf}}</ref> Variation in plumage also allows for the identification of birds, particularly between species. Visual communication among birds may also involve ritualised displays, which have developed from non-signalling actions such as preening, the adjustments of feather position, pecking, or other behaviour. These displays may signal aggression or submission or may contribute to the formation of pair-bonds.<ref name = "Gill"/> The most elaborate displays occur during courtship, where "dances" are often formed from complex combinations of many possible component movements;<ref>{{cite journal |last=Pickering |first=S. P. C. |coauthors=S. D. Berrow |year=2001 |title=Courtship behaviour of the Wandering Albatross ''Diomedea exulans'' at Bird Island, South Georgia |journal=Marine Ornithology |volume=29 |issue=1 |pages=29–37 |url=http://www.marineornithology.org/PDF/29_1/29_1_6.pdf}}</ref> males' breeding success may depend on the quality of such displays.<ref>{{cite journal |last=Pruett-Jones |first=S. G. |coauthors=M. A. Pruett-Jones |month=May |year=1990 |title=Sexual Selection Through Female Choice in Lawes' Parotia, A Lek-Mating Bird of Paradise |journal=[[Evolution (journal)|Evolution]] |volume=44 |issue=3 |pages=486–501 |doi=10.2307/2409431}}</ref> [[Image:Troglodytes aedon.ogg|thumb|right|Call of the [[House Wren]], a common North American songbird]] [[Bird vocalization|Bird calls and songs]], which are produced in the [[Syrinx (biology)|syrinx]], are the major means by which birds communicate with [[sound]]. This communication can be very complex; some species can operate the two sides of the syrinx independently, allowing the simultaneous production of two different songs.<ref name = "Suthers"/> Calls are used for a variety of purposes, including mate attraction,<ref name = "Gill"/> evaluation of potential mates,<ref>{{cite journal |last=Genevois |first=F. |coauthors=V. Bretagnolle |year=1994 |title=Male Blue Petrels reveal their body mass when calling |journal=Ethology Ecology and Evolution |volume=6 |issue=3 |pages=377–83 |url=http://ejour-fup.unifi.it/index.php/eee/article/view/667/613}}</ref> bond formation, the claiming and maintenance of territories,<ref name = "Gill"/> the identification of other individuals (such as when parents look for chicks in colonies or when mates reunite at the start of breeding season<ref>{{cite journal |last=Jouventin |first=Pierre |coauthors=Thierry Aubin and Thierry Lengagne |month= |year=1999 |title=Finding a parent in a king penguin colony: the acoustic system of individual recognition |journal=Animal Behaviour |volume=57 |issue=6 |pages=1175–83 |doi=10.1006/anbe.1999.1086 |pmid=10373249}}</ref>), and the warning of other birds of potential predators, sometimes with specific information about the nature of the threat.<ref>{{cite journal |last=Templeton |first=Christopher N. |coauthorserik= Greene and Kate Davis |year=2005 |title=Allometry of Alarm Calls: Black-Capped Chickadees Encode Information About Predator Size |journal=Science |volume=308 |issue=5730 |pages=1934–37 |doi=10.1126/science.1108841 |pmid=15976305}}</ref> Some birds also use mechanical sounds for auditory communication. The ''[[Coenocorypha]]'' [[snipe]]s of [[New Zealand]] drive air through their feathers,<ref name = "Miskelly">{{cite journal |last=Miskelly |first=C. M. |coauthors= |month=July |year=1987 |title=The identity of the hakawai |journal=Notornis |volume=34 |issue=2 |pages=95–116 |url=http://www.notornis.org.nz/free_issues/Notornis_34-1987/Notornis_34_2.pdf}}</ref> [[woodpecker]]s drum territorially,<ref name = Attenborough"/> and [[Palm Cockatoo]]s use tools to drum.<ref>{{cite journal |last=Murphy |first=Stephen |coauthors=Sarah Legge and Robert Heinsohn |year=2003 |title=The breeding biology of palm cockatoos (''Probosciger aterrimus''): a case of a slow life history |journal=[[Journal of Zoology]] |volume=261 |issue=4 |pages=327–39 |doi=10.1017/S0952836903004175}}</ref> ===Flocking and other associations=== [[Image:Red-billed quelea flocking at waterhole.jpg|thumb|right|[[Red-billed Quelea]]s, the most numerous species of bird,<ref name = "flycatcher">{{cite book |last= Sekercioglu |first=Cagan Hakki |year=2006 |chapter=Foreword |title=[[Handbook of the Birds of the World]], Volume 11: Old World Flycatchers to Old World Warblers |editor=Josep del Hoyo, Andrew Elliott & David Christie (eds.) |location=Barcelona |publisher=Lynx Edicions |isbn=84-96553-06-X| pages=p. 48}}</ref> form enormous flocks&mdash;sometimes tens of thousands strong.]] While some birds are essentially territorial or live in small family groups, other birds may form large [[flock (birds)|flocks]]. The principal benefits of flocking are [[safety in numbers]] and increased foraging efficiency.<ref name = "Gill"/> Defence against predators is particularly important in closed habitats like forests, where [[ambush predation]] is common and multiple eyes can provide a valuable early warning system. This has led to the development of many [[mixed-species feeding flock]]s, which are usually composed of small numbers of many species; these flocks provide safety in numbers but reduce potential competition for resources.<ref>{{cite journal |last=Terborgh |first=John |year=2005 |title=Mixed flocks and polyspecific associations: Costs and benefits of mixed groups to birds and monkeys |journal=American Journal of Primatology |volume=21 |issue= 2|pages=87–100 |doi=10.1002/ajp.1350210203}}</ref> Costs of flocking include bullying of socially subordinate birds by more dominant birds and the reduction of feeding efficiency in certain cases.<ref>{{cite journal |last=Hutto |first=Richard L. |month=January |year=988 |title=Foraging Behavior Patterns Suggest a Possible Cost Associated with Participation in Mixed-Species Bird Flocks |journal=[[Oikos (journal)|Oikos]] |volume=51 |issue=1 |pages=79–83 |doi=10.2307/3565809}}</ref> Birds sometimes also form associations with non-avian species. Plunge-diving [[seabird]]s associate with [[dolphin]]s and [[tuna]], which push shoaling fish towards the surface.<ref name = "AU">{{cite journal |last=Au |first= David W. K. |coauthors=Robert L. Pitman |month=August |year=1986 |title=Seabird interactions with Dolphins and Tuna in the Eastern Tropical Pacific |journal=The Condor |volume=88 |issue=3 |pages=304–17 |url=http://elibrary.unm.edu/sora/Condor/files/issues/v088n03/p0304-p0317.pdf |doi=10.2307/1368877}}</ref> Hornbills have a [[mutualism|mutualistic relationship]] with [[Dwarf Mongoose]]s, in which they forage together and warn each other of nearby [[birds of prey]] and other predators.<ref>{{cite journal |last=Anne |first= O. |coauthors=E. Rasa |month=June |year=1983 |title=Dwarf mongoose and hornbill mutualism in the Taru desert, Kenya |journal=Behavioral Ecology and Sociobiology |volume=12 |issue=3 |pages=181–90 |doi=10.1007/BF00290770}}</ref> {{-}} ===Resting and roosting===<!--Roosting redirects here--> The high metabolic rates of birds during the active part of the day is supplemented by rest at other times. Sleeping birds often use a type of sleep known as vigilant sleep, where periods of rest are interspersed with quick eye-opening 'peeks', allowing them to be sensitive to disturbances and enable rapid escape from threats.<ref>{{cite journal |last=Gauthier-Clerc |first=Michael |coauthors=Alain Tamisier, Frank Cezilly |month=May |year=2000 |title=Sleep-Vigilance Trade-off in Gadwall during the Winter Period |journal=The Condor |volume=102 |issue=2 |pages=307–13 |url=http://elibrary.unm.edu/sora/Condor/files/issues/v102n02/p0307-p0313.pdf |doi=10.1650/0010-5422(2000)102[0307:SVTOIG]2.0.CO;2}}</ref> [[Swift]]s have been widely believed to be able to sleep while flying; however, this has not been confirmed by experimental evidence. However, there may be certain kinds of sleep which are possible even when in flight.<ref>{{cite journal|last=Rattenborg|first= Niels C. |year=2006 |title=Do birds sleep in flight? |journal=Die Naturwissenschaften |volume=93 |issue=9 |pages=413–25 |doi=10.1007/s00114-006-0120-3}}</ref> Some birds have also demonstrated the capacity to fall into [[slow-wave sleep]] one [[Cerebral hemisphere|hemisphere]] of the brain at a time. The birds tend to exercise this ability depending upon its position relative to the outside of the flock. This may allow the eye opposite the sleeping hemisphere to remain vigilant for [[predator]]s by viewing the outer margins of the flock. This adaptation is also known from [[marine mammal]]s.<ref>{{cite journal |last=Milius |first=S. |year=1999 |title=Half-asleep birds choose which half dozes |journal=Science News Online |volume=155 |issue= |pages=86 |url=http://findarticles.com/p/articles/mi_m1200/is_6_155/ai_53965042 |doi=10.2307/4011301}}</ref> Communal roosting is common because it lowers the [[thermoregulation|loss of body heat]] and decreases the risks associated with predators.<ref>{{cite journal |last=Beauchamp |first=Guy |year=1999 |title=The evolution of communal roosting in birds: origin and secondary losses |journal=Behavioural Ecology |volume=10 |issue=6 |pages=675–87 |url=http://beheco.oxfordjournals.org/cgi/content/full/10/6/675 |doi=10.1093/beheco/10.6.675 }}</ref> Roosting sites are often chosen with regard to thermoregulation and safety.<ref>{{cite journal |last=Buttemer |first=William A.|year=1985 |title=Energy relations of winter roost-site utilization by American goldfinches (''Carduelis tristis'') |journal=[[Oecologia]] |volume=68 |issue=1 |pages=126–32 |url= http://deepblue.lib.umich.edu/dspace/bitstream/2027.42/47760/1/442_2004_Article_BF00379484.pdf |doi=10.1007/BF00379484}}</ref> Many sleeping birds bend their heads over their backs and tuck their [[beak|bills]] in their back feathers, although others place their beaks among their breast feathers. Many birds rest on one leg, while some may pull up their legs into their feathers, especially in cold weather. Perching birds have a tendon locking mechanism that helps them hold on to the perch when they are asleep. Many ground birds, such as quails and pheasants, roost in trees. A few parrots of the genus ''[[Loriculus]]'' roost hanging upside down.<ref>{{cite journal |last=Buckley |first=F. G. |coauthors=P. A. Buckley |year=1968 |title=Upside-down Resting by Young Green-Rumped Parrotlets (''Forpus passerinus'') |journal=The Condor |volume=70 |issue=1 |pages= 89 |doi=10.2307/1366517}}</ref> Some [[hummingbird]]s go into a nightly state of [[torpor]] accompanied with a reduction of their metabolic rates.<ref>{{cite journal |last=Carpenter |first=F. Lynn |year=1974 |title=Torpor in an Andean Hummingbird: Its Ecological Significance |journal=Science |volume=183 |issue=4124 |pages=545–47 |doi=10.1126/science.183.4124.545 |pmid=17773043}}</ref> This [[Adaptation|physiological adaptation]] shows nearly a hundred other species, including [[owlet-nightjar]]s, [[nightjar]]s, and [[woodswallow]]s. One species, the [[Common Poorwill]], even enters a state of [[hibernation]].<ref>{{cite journal |last=McKechnie |first=Andrew E. |coauthors=Robert A. M. Ashdown, Murray B. Christian and R. Mark Brigham |year=2007 |title=Torpor in an African caprimulgid, the freckled nightjar ''Caprimulgus tristigma'' |journal=Journal of Avian Biology |volume=38 |issue=3 |pages= 261–66 |doi=10.1111/j.2007.0908-8857.04116.x}}</ref> Birds do not have sweat glands, but they may cool themselves by moving to shade, standing in water, panting, increasing their surface area, fluttering their throat or by using special behaviours like [[urohydrosis]] to cool themselves. ===Breeding=== ====Social systems==== [[Image:Phalaropus lobatus.jpg|thumb|right|[[Red-necked Phalarope]]s have an unusual polyandrous mating system where males care for the eggs and chicks and brightly coloured females compete for males.<ref> Warnock, Nils & Sarah (2001). "Sandpipers, Phalaropes and Allies" in ''The Sibley Guide to Bird Life and Behaviour'' (eds Chris Elphick, John B. Dunning, Jr & David Sibley) London: Christopher Helm, ISBN 0-7136-6250-6 </ref>]] Ninety-five percent of bird species are [[Varieties of monogamy|socially monogamous]]. These species pair for at least the length of the breeding season or—in some cases—for several years or until the death of one mate.<ref>{{cite journal|last=Freed|first=Leonard A.|year=1987|title=The Long-Term Pair Bond of Tropical House Wrens: Advantage or Constraint?|journal=[[The American Naturalist]]|volume=130|issue=4|pages=507–25|doi=10.1086/284728}}</ref> Monogamy allows for [[Parental investment|biparental care]], which is especially important for species in which females require males' assistance for successful brood-rearing.<ref>{{cite journal|last=Gowaty|first=Patricia A.|title=Male Parental Care and Apparent Monogamy among Eastern Bluebirds(''Sialia sialis'')|journal=[[The American Naturalist]]|volume=121|issue=2|pages=149–60|year=1983|doi=10.1086/284047}}</ref> Among many socially monogamous species, extra-pair copulation (infidelity) is common.<ref>{{cite journal|last=Westneat|first=David F.|coauthors=Ian R. K. Stewart|year=2003|title=Extra-pair paternity in birds: Causes, correlates, and conflict|url=http://arjournals.annualreviews.org/doi/pdf/10.1146/annurev.ecolsys.34.011802.132439 | doi = 10.1146/annurev.ecolsys.34.011802.132439 <!--Retrieved from url by DOI bot-->|journal=[[Annual Review of Ecology, Evolution, and Systematics]]|volume=34|pages=365–96}}</ref> Such behaviour typically occurs between dominant males and females paired with subordinate males, but may also be the result of forced copulation in ducks and other [[anatidae|anatid]]s.<ref>{{cite journal|last=Gowaty|first=Patricia A.|coauthors=Nancy Buschhaus|year=1998|url=http://findarticles.com/p/articles/mi_qa3746/is_199802/ai_n8791262|title=Ultimate causation of aggressive and forced copulation in birds: Female resistance, the CODE hypothesis, and social monogamy|journal=[[American Zoologist]]|volume=38|issue=1|pages=207–25|doi=10.1093/icb/38.1.207}}</ref> For females, possible benefits of extra-pair copulation include getting better genes for her offspring and insuring against the possibility of infertility in her mate.<ref>{{cite journal|last=Sheldon|first=B|year=1994|title=Male Phenotype, Fertility, and the Pursuit of Extra-Pair Copulations by Female Birds|journal=Proceedings: Biological Sciences|volume=257|issue=1348|pages=25–30|doi=10.1098/rspb.1994.0089}}</ref> Males of species that engage in extra-pair copulations will closely guard their mates to ensure the parentage of the offspring that they raise.<ref>{{cite journal|last=Wei|first=G|coauthors=Z Yin, F Lei|year=2005|title=Copulations and mate guarding of the Chinese Egret | doi = 10.1675/1524-4695(2005)28[527:CAMGOT]2.0.CO;2 <!--Retrieved from Yahoo! by DOI bot-->|journal=Waterbirds|volume=28|issue=4|pages=527–30}}</ref> Other mating systems, including [[polygyny]], [[polyandry]], [[polygamy]], [[polygynandry]], and [[promiscuity]], also occur.<ref name = "Gill"/> Polygamous breeding systems arise when females are able to raise broods without the help of males.<ref name = "Gill"/> Some species may use more than one system depending on the circumstances. Breeding usually involves some form of courtship display, typically performed by the male.<ref>{{cite book|last=Short|first=Lester L.|year=1993|title=Birds of the World and their Behavior|publisher=Henry Holt and Co|location=New York|isbn=0-8050-1952-9}}</ref> Most displays are rather simple and involve some type of [[bird song|song]]. Some displays, however, are quite elaborate. Depending on the species, these may include wing or tail drumming, dancing, aerial flights, or communal [[lek (mating arena)|lek]]king. Females are generally the ones that drive partner selection,<ref>{{cite book|last=Burton|first=R|year=1985|title=Bird Behavior|publisher=Alfred A. Knopf, Inc.|isbn=0-394-53857-5}}</ref> although in the polyandrous [[phalaropes]], this is reversed: plainer males choose brightly coloured females.<ref>{{cite journal|last=Schamel|first=D|coauthors=DM Tracy, DB Lank, DF Westneat|year=2004|title=Mate guarding, copulation strategies and paternity in the sex-role reversed, socially polyandrous red-necked phalarope ''Phalaropus lobatus''|journal=Behaviour Ecology and Sociobiology|volume=57|issue=2|pages=110–18|url=http://www.springerlink.com/index/8BE48GKGYF2Q40LT.pdf|doi=10.1007/s00265-004-0825-2}}</ref> Courtship feeding, [[Beak#Billing|billing]] and allopreening are commonly performed between partners, generally after the birds have paired and mated.<ref name = Attenborough"/> ====Territories, nesting and incubation==== {{See also|Bird nest}} Many birds actively defend a territory from others of the same species during the breeding season; maintenance of territories protects the food source for their chicks. Species that are unable to defend feeding territories, such as [[seabird]]s and [[swift]]s, often breed in [[Colony (biology)|colonies]] instead; this is thought to offer protection from predators. Colonial breeders defend small nesting sites, and competition between and within species for nesting sites can be intense.<ref>Kokko H, Harris M, Wanless S (2004). "Competition for breeding sites and site-dependent population regulation in a highly colonial seabird, the common guillemot ''Uria aalge''." ''Journal of Animal Ecology'' '''73''' (2): 367–76. {{DOI|10.1111/j.0021-8790.2004.00813.x}}</ref> [[Image:Webervogelnst Auoblodge.JPG|thumb|left|The nesting colonies of the [[Sociable Weaver]] are amongst the largest bird-created structures.]] All birds lay [[amniotic egg]]s with hard shells made mostly of [[calcium carbonate]].<ref name = "Gill"/> Hole and burrow nesting species tend to lay white or pale eggs, while open nesters lay [[camouflage]]d eggs. There are many exceptions to this pattern, however; the ground-nesting [[nightjar]]s have pale eggs, and camouflage is instead provided by their plumage. Species that are victims of [[brood parasites]] have varying egg colours to improve the chances of spotting a parasite's egg, which forces female parasites to match their eggs to those of their hosts.<ref>Booker L, Booker M (1991). "Why Are Cuckoos Host Specific?" ''[[Oikos (journal)|Oikos]]'' '''57''' (3): 301–09. {{DOI|10.2307/3565958}}</ref> Bird eggs are usually laid in a [[Bird nest|nest]]. Most species create somewhat elaborate nests, which can be cups, domes, plates, beds scrapes, mounds, or burrows.<ref name = "Hansell">Hansell M (2000). ''Bird Nests and Construction Behaviour''. University of Cambridge Press ISBN 0-521-46038-7</ref> Some bird nests, however, are extremely primitive; [[albatross]] nests are no more than a scrape on the ground. Most birds build nests in sheltered, hidden areas to avoid predation, but large or colonial birds—which are more capable of defence—may build more open nests. During nest construction, some species seek out plant matter from plants with parasite-reducing toxins to improve chick survival,<ref>Lafuma L, Lambrechts M, Raymond M (2001). "Aromatic plants in bird nests as a protection against blood-sucking flying insects?" ''Behavioural Processes'' '''56''' (2) 113–20. {{DOI|10.1016/S0376-6357(01)00191-7}}</ref> and feathers are often used for nest insulation.<ref name = "Hansell"/> Some bird species have no nests; the cliff-nesting [[Common Guillemot]] lays its eggs on bare rock, and male [[Emperor Penguin]]s keep eggs between their body and feet. The absence of nests is especially prevalent in ground-nesting species where the newly hatched young are [[precocial]]. Incubation, which optimises temperature for chick development, usually begins after the last egg has been laid.<ref name = "Gill"/> In monogamous species incubation duties are often shared, whereas in polygamous species one parent is wholly responsible for incubation. Warmth from parents passes to the eggs through [[brood patch]]es, areas of bare skin on the abdomen or breast of the incubating birds. Incubation can be an energetically demanding process; adult albatrosses, for instance, lose as much as {{convert|83|g}} of body weight per day of incubation.<ref>Warham, J. (1990) ''The Petrels - Their Ecology and Breeding Systems'' London: [[Academic Press]] ISBN 0127354204.</ref> The warmth for the incubation of the eggs of [[megapode]]s comes from the sun, decaying vegetation or volcanic sources.<ref>Jones DN, Dekker, René WRJ, Roselaar, Cees S (1995). ''The Megapodes''. Bird Families of the World 3. [[Oxford University Press]]: Oxford. ISBN 0-19-854651-3</ref> Incubation periods range from 10 days (in [[woodpecker]]s, [[cuckoo]]s and [[passerine]] birds) to over 80 days (in albatrosses and [[kiwi]]s).<ref name = "Gill"/> ====Parental care and fledging==== [[Image:Nectarinia dussumieri feeding young.jpg|thumb|upright|right|A female [[Seychelles Sunbird]] with [[spider|arachnid]] prey attending its nest]] At the time of their hatching, chicks range in development from helpless to independent, depending on their species. Helpless chicks are termed ''[[altricial]]'', and tend to be born small, [[Blindness|blind]], immobile and naked; chicks that are mobile and feathered upon hatching are termed ''[[precocial]]''. Altricial chicks need help [[thermoregulation|thermoregulating]] and must be brooded for longer than precocial chicks. Chicks at neither of these extremes can be semi-precocial or semi-altricial. The length and nature of parental care varies widely amongst different orders and species. At one extreme, parental care in [[megapode]]s ends at hatching; the newly-hatched chick digs itself out of the nest mound without parental assistance and can fend for itself immediately.<ref>Elliot A (1994). "Family Megapodiidae (Megapodes)" in ''[[Handbook of the Birds of the World]]. Volume 2; New World Vultures to Guineafowl'' (eds del Hoyo J, Elliott A, Sargatal J) Lynx Edicions:Barcelona. ISBN 84-873337-15-6 </ref> At the other extreme, many seabirds have extended periods of parental care, the longest being that of the [[Great Frigatebird]], whose chicks take up to six months to [[fledge]] and are fed by the parents for up to an additional 14 months.<ref>Metz VG, Schreiber EA (2002). "Great Frigatebird (''Fregata minor'')" In ''The Birds of North America, No 681'', (Poole, A. & Gill, F., eds) The Birds of North America Inc: Philadelphia </ref> [[Image:Ardea herodias at the nest 11.jpg|left|[[Great Blue Heron]] parents and chicks at the nest|thumb]] In some species, both parents care for nestlings and fledglings; in others, such care is the responsibility of only one sex. In some species, [[helpers at the nest|other member]]s of the same species&mdash;usually close relatives of the breeding pair, such as offspring from previous broods&mdash;will help with the raising of the young.<ref>Ekman J (2006). "Family living amongst birds." ''[[Journal of Avian Biology]]'' '''37''' (4): 289–98. {{DOI|10.1111/j.2006.0908-8857.03666.x}}</ref> Such alloparenting is particularly common among the [[Corvida]], which includes such birds as the true [[Corvidae|crows]], [[Australian Magpie]] and [[Fairy-wren]]s,<ref>{{cite book |author=Cockburn A|editor=Floyd R, Sheppard A, de Barro P|title=Frontiers in Population Ecology|year=1996|publisher=CSIRO|location=Melbourne|isbn= |pages=21–42|chapter=Why do so many Australian birds cooperate? Social evolution in the Corvida}}</ref> but has been observed in species as different as the [[Rifleman (bird)|Rifleman]] and [[Red Kite]]. Among most groups of animals, male parental care is rare. In birds, however, it is quite common&mdash;more so than in any other vertebrate class.<ref name = "Gill"/> Though territory and nest site defence, incubation, and chick feeding are often shared tasks, there is sometimes a division of labour in which one mate undertakes all or most of a particular duty.<ref>{{cite journal|last=Cockburn|first=Andrew|year=2006|title=Prevalence of different modes of parental care in birds | doi = 10.1098/rspb.2005.3458 <!--Retrieved from Yahoo! by DOI bot-->|journal=Proceedings: Biological Sciences|volume=273|issue=1592|pages=1375–83|pmid=16777726}}</ref> The point at which chicks [[fledge]] varies dramatically. The chicks of the ''[[Synthliboramphus]]'' murrelets, like the [[Ancient Murrelet]], leave the nest the night after they hatch, following their parents out to sea, where they are raised away from terrestrial predators.<ref>Gaston AJ (1994). Ancient Murrelet (''Synthliboramphus antiquus''). In ''The Birds of North America, No. 132'' (A. Poole and F. Gill, Eds.). Philadelphia: The Academy of Natural Sciences; Washington, D.C.: The American Ornithologists' Union.</ref> Some other species, such as ducks, move their chicks away from the nest at an early age. In most species, chicks leave the nest just before, or soon after, they are able to fly. The amount of parental care after fledging varies; albatross chicks leave the nest on their own and receive no further help, while other species continue some supplementary feeding after fledging.<ref>Schaefer HC, Eshiamwata GW, Munyekenye FB, Bohning-Gaese K (2004). "Life-history of two African ''Sylvia'' warblers: low annual fecundity and long post-fledging care." ''[[Ibis (journal)|Ibis]]'' '''146''' (3): 427–37. {{DOI|10.1111/j.1474-919X.2004.00276.x}}</ref> Chicks may also follow their parents during their first [[bird migration|migration]].<ref> Alonso JC, Bautista LM, Alonso JA (2004). "Family-based territoriality vs flocking in wintering common cranes ''Grus grus''." ''[[Journal of Avian Biology]]'' '''35''' (5): 434–44. {{DOI|10.1111/j.0908-8857.2004.03290.x}}</ref> ====Brood parasites==== {{main|Brood parasite}} [[Image:Reed warbler cuckoo.jpg|thumb|100px|upright|right|This [[Reed Warbler]] is raising the young of a [[Common Cuckoo]], a [[brood parasite]].]] [[Brood parasitism]], in which an egg-layer leaves her eggs with another individual's brood, is more common among birds than any other type of organism.<ref name = "brood">Davies N (2000). ''Cuckoos, Cowbirds and other Cheats''. [[T. & A. D. Poyser]]: London ISBN 0-85661-135-2</ref> After a parasitic bird lays her eggs in another bird's nest, they are often accepted and raised by the host at the expense of the host's own brood. Brood parasites may be either ''obligate brood parasites'', which must lay their eggs in the nests of other species because they are incapable of raising their own young, or ''non-obligate brood parasites'', which sometimes lay eggs in the nests of [[conspecific]]s to increase their reproductive output even though they could have raised their own young.<ref>Sorenson M (1997). "Effects of intra- and interspecific brood parasitism on a precocial host, the canvasback, ''Aythya valisineria''." ''Behavioral Ecology'' '''8''' (2) 153–61. [http://beheco.oxfordjournals.org/cgi/reprint/8/2/153.pdf PDF]</ref> One hundred bird species, including [[honeyguide]]s, [[icterid]]s, [[estrildid finch]]es and [[Black-headed Duck|ducks]], are obligate parasites, though the most famous are the [[cuckoo]]s.<ref name = "brood"/> Some brood parasites are adapted to hatch before their host's young, which allows them to destroy the host's eggs by pushing them out of the nest or to kill the host's chicks; this ensures that all food brought to the nest will be fed to the parasitic chicks.<ref>Spottiswoode C, Colebrook-Robjent J (2007). "Egg puncturing by the brood parasitic Greater Honeyguide and potential host counteradaptations." ''Behavioral Ecology'' {{DOI|10.1093/beheco/arm025}}</ref> ==Ecology== [[Image:Skua and penguin.jpeg|thumb|left|The [[South Polar Skua]] (left) is a generalist predator, taking the eggs of other birds, fish, carrion and other animals. This skua is attempting to push an [[Adelie Penguin]] (right) off its nest]] Birds occupy a wide range of ecological positions.<ref name = "flycatcher"/> While some birds are generalists, others are highly specialised in their habitat or food requirements. Even within a single habitat, such as a forest, the [[Ecological niche|niche]]s occupied by different species of birds vary, with some species feeding in the forest canopy, others beneath the canopy, and still others on the forest floor. Forest birds may be [[insectivore]]s, [[frugivore]]s, and [[nectarivore]]s. Aquatic birds generally feed by fishing, plant eating, and piracy or [[kleptoparasitism]]. Birds of prey specialise in hunting mammals or other birds, while vultures are specialised [[scavenger]]s. Some nectar-feeding birds are important pollinators, and many frugivores play a key role in seed dispersal.<ref name = "Clout">Clout M, Hay J (1989). "The importance of birds as browsers, pollinators and seed dispersers in New Zealand forests." ''New Zealand Journal of Ecology'' '''12''' 27–33 [http://www.newzealandecology.org/nzje/free_issues/NZJEcol12_s_27.pdf PDF]</ref> Plants and pollinating birds often [[coevolution|coevolve]],<ref>Stiles F (1981). "Geographical Aspects of Bird–Flower Coevolution, with Particular Reference to Central America." ''Annals of the Missouri Botanical Garden'' '''68''' (2) 323–51. {{DOI|10.2307/2398801}}</ref> and in some cases a flower's primary pollinator is the only species capable of reaching its nectar.<ref>Temeles E, Linhart Y, Masonjones M, Masonjones H (2002). "The Role of Flower Width in Hummingbird Bill Length–Flower Length Relationships." ''Biotropica'' '''34''' (1): 68–80. [http://www.amherst.edu/~ejtemeles/Temeles%20et%20al%202002%20biotropica.pdf PDF]</ref> Birds are often important to island ecology. Birds have frequently reached islands that mammals have not; on those islands, birds may fulfill ecological roles typically played by larger animals. For example, in New Zealand the [[moa]]s were important browsers, as are the [[Kereru]] and [[Kokako]] today.<ref name = "Clout"/> Today the plants of New Zealand retain the defensive adaptations evolved to protect them from the extinct moa.<ref>Bond W, Lee W, Craine J (2004). "Plant structural defences against browsing birds: a legacy of New Zealand's extinct moas." ''[[Oikos (journal)|Oikos]]'' '''104''' (3), 500–08. {{DOI|10.1111/j.0030-1299.2004.12720.x}}</ref> Nesting [[seabird]]s may also affect the ecology of islands and surrounding seas, principally through the concentration of large quantities of [[guano]], which may enrich the local soil<ref>Wainright S, Haney J, Kerr C, Golovkin A, Flint M (1998). "Utilization of nitrogen derived from seabird guano by terrestrial and marine plants at St. Paul, Pribilof Islands, Bering Sea, Alaska." ''Marine Ecology'' '''131''' (1) 63–71. [http://www.springerlink.com/index/DN8D70RYM7TUF42P.pdf PDF]</ref> and the surrounding seas.<ref>Bosman A, Hockey A (1986). "Seabird guano as a determinant of rocky intertidal community structure." ''Marine Ecology Progress Series'' '''32''': 247–57 [http://www.int-res.com/articles/meps/32/m032p247.pdf PDF]</ref> ==Relationship with humans== [[Image:Industrial-Chicken-Coop.JPG|thumb|right|Industrial farming of chickens.]] Since birds are highly visible and common animals, humans have had a relationship with them since the dawn of man.<ref>{{Citation| last = Bonney| first = Rick | last2 = Rohrbaugh, Jr.| first2 = Ronald| title = Handbook of Bird Biology| place= Princeton, NJ| publisher = Princeton University Press| year = 2004| edition = Second| isbn = 0-938-02762-X}}</ref> Sometimes, these relationships are [[Mutualism|mutualistic]], like the cooperative honey-gathering among [[honeyguide]]s and African peoples such as the [[Borana people|Borana]].<ref>Dean W, Siegfried R, MacDonald I (1990). "The Fallacy, Fact, and Fate of Guiding Behavior in the Greater Honeyguide." ''Conservation Biology'' '''4''' (1) 99–101. [http://www.blackwell-synergy.com/doi/abs/10.1111/j.1523-1739.1990.tb00272.x PDF]</ref> Other times, they may be [[Commensalism|commensal]], as when species such as the [[House Sparrow]]<ref>Singer R, Yom-Tov Y (1988). "The Breeding Biology of the House Sparrow ''Passer domesticus'' in Israel." ''[[Ornis Scandinavica]]'' '''19''' 139–44. {{DOI|10.2307/3676463}}</ref> have benefited from human activities. Several bird species have become commercially significant agricultural pests,<ref>Dolbeer R (1990). "Ornithology and integrated pest management: Red-winged blackbirds ''Agleaius phoeniceus'' and corn." ''[[Ibis (journal)|Ibis]]'' '''132''' (2): 309–22.</ref> and some pose an [[bird strike|aviation hazard]].<ref>Dolbeer R, Belant J, Sillings J (1993). "Shooting Gulls Reduces Strikes with Aircraft at John F. Kennedy International Airport." ''Wildlife Society Bulletin '' '''21''': 442–50. </ref> Human activities can also be detrimental, and have threatened numerous bird species with extinction. Birds can act as vectors for spreading diseases such as [[psittacosis]], [[salmonellosis]], [[campylobacteriosis]], mycobacteriosis (avian [[tuberculosis]]), [[avian influenza]] (bird flu), [[giardiasis]], and [[cryptosporidiosis]] over long distances. Some of these are [[zoonosis|zoonotic diseases]] that can also be transmitted to humans.<ref>Reed KD, Meece JK, Henkel JS, Shukla SK (2003). [http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1069015 "Birds, Migration and Emerging Zoonoses: West Nile Virus, Lyme Disease, Influenza A and Enteropathogens."] Clin Med Res. '''1''' (1):5–12. PMID 15931279 </ref> ===Economic importance=== Domesticated birds raised for meat and eggs, called [[poultry]], are the largest source of animal protein eaten by humans; in 2003, 76 million tons of poultry and 61 million tons of eggs were produced worldwide.<ref>[http://www.earth-policy.org/Books/Out/Ote3_3.htm Shifting protein sources: Chapter 3: Moving Up the Food Chain Efficiently.] Earth Policy Institute. Retrieved on [[December 18]], [[2007]].</ref> [[Chicken]]s account for much of human poultry consumption, though turkeys, ducks, and geese are also relatively common. Many species of birds are also hunted for meat. Bird hunting is primarily a recreational activity except in extremely undeveloped areas. The most important birds hunted in North and South America are waterfowl; other widely hunted birds include [[pheasant]]s, [[turkey (bird)|wild turkeys]], [[quail]], [[dove]]s, [[partridge]], [[grouse]], [[snipe]], and [[woodcock]].<ref>Simeone A, Navarro X (2002). [http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-078X2002000200012&lng=es&nrm=iso&tlng=en "Human exploitation of seabirds in coastal southern Chile during the mid-Holocene."] ''Rev. chil. hist. nat'' '''75''' (2): 423–31 </ref> [[Muttonbirding]] is also popular in Australia and New Zealand.<ref>Hamilton S (2000). "How precise and accurate are data obtained using. an infra-red scope on burrow-nesting sooty shearwaters ''Puffinus griseus''?" ''Marine Ornithology'' '''28''' (1): 1–6 [http://www.marineornithology.org/PDF/28_1/28_1_1.pdf PDF]</ref> Though some hunting, such as that of muttonbirds, may be sustainable, hunting has led to the extinction or endangerment of dozens of species.<ref> Keane A, Brooke MD, Mcgowan PJK (2005). "Correlates of extinction risk and hunting pressure in gamebirds (Galliformes)." ''Biological Conservation'' '''126''' (2): 216–33. {{DOI|10.1016/j.biocon.2005.05.011}}</ref> Other commercially valuable products from birds include feathers (especially the [[down]] of geese and ducks), which are used as insulation in clothing and bedding, and seabird feces ([[guano]]), which is a valuable source of phosphorus and nitrogen. The [[War of the Pacific]], sometimes called the Guano War, was fought in part over the control of guano deposits.<ref>[http://www.zum.de/whkmla/military/19cen/guanowar.html The Guano War of 1865-1866.] World History at KMLA. Retrieved on [[December 18]], [[2007]].</ref> [[Image:FishingCormorants.jpg|thumb|upright|The use of cormorants by Asian fishermen is in steep decline but survives in some areas as a tourist attraction.]] Birds have been domesticated by humans both as pets and for practical purposes. Colourful birds, such as [[Parrot (family)|parrots]] and [[myna]]s, are bred in [[aviculture|captivity]] or kept as pets, a practice that has led to the illegal trafficking of some endangered species.<ref>Cooney R, Jepson P (2006). "The international wild bird trade: what's wrong with blanket bans?" ''Oryx'' '''40''' (1): 18–23. [http://journals.cambridge.org/production/action/cjoGetFulltext?fulltextid=409231 PDF]</ref> [[Falcon]]s and [[cormorant]]s have long been used for hunting and fishing, respectively. [[Messenger pigeon]]s, used since at least 1 AD, remained important as recently as World War II. Today, such activities are more common either as hobbies, for entertainment and tourism,<ref>Manzi M (2002). [http://findarticles.com/p/articles/mi_go1895/is_200210/ai_n8674873 "Cormorant fishing in Southwestern China: a Traditional Fishery under Siege. (Geographical Field Note)."] ''Geographic Review'' '''92''' (4): 597–603.</ref> or for sports such as [[pigeon racing]]. Amateur bird enthusiasts (called birdwatchers, twitchers or, more commonly, [[birding|birders]]) number in the millions.<ref>Pullis La Rouche, G. (2006). Birding in the United States: a demographic and economic analysis. ''Waterbirds around the world.'' Eds. G.C. Boere, C.A. Galbraith & D.A. Stroud. [[The Stationery Office]], Edinburgh, UK. pp. 841–46. [http://www.jncc.gov.uk/PDF/pub07_waterbirds_part6.2.5.pdf PDF]</ref> Many homeowners erect [[bird feeder]]s near their homes to attract various species. [[Bird feeding]] has grown into a multimillion dollar industry; for example, an estimated 75% of households in Britain provide food for birds at some point during the winter.<ref>Chamberlain DE, Vickery JA, Glue DE, Robinson RA, Conway GJ, Woodburn RJW, Cannon AR (2005). "Annual and seasonal trends in the use of garden feeders by birds in winter." ''[[Ibis (journal)|Ibis]]'' '''147''' (3): 563–75. [http://www.blackwell-synergy.com/doi/pdf/10.1111/j.1474-919x.2005.00430.x PDF]</ref> [[Image:Vogel Drei (Meister der Spielkarten).jpg|thumb|upright|left|"The 3 of Birds" by the [[Master of the Playing Cards]], 16th century Germany]] ===Religion, folklore and culture=== Birds play prominent and diverse roles in folklore, religion, and popular culture. In religion, birds may serve as either messengers or priests and leaders for a [[deity]], such as in the Cult of [[Makemake (mythology)|Makemake]], in which the [[Tangata manu]] of [[Easter Island]] served as chiefs,<ref>Routledge S, Routledge K (1917). "The Bird Cult of Easter Island." ''Folklore'' '''28''' (4): 337–55.</ref> or as attendants, as in the case of [[Hugin and Munin]], two [[Common Raven]]s who whispered news into the ears of the [[Norse god]] [[Odin]].<ref>Chappell J (2006). [http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=1326277 "Living with the Trickster: Crows, Ravens, and Human Culture."] ''PLoS Biol'' '''4''' (1):e14. {{DOI|10.1371/journal.pbio.0040014}}</ref> They may also serve as religious symbols, as when [[Jonah]] (Hebrew: '''יוֹנָה''', [[dove]]) embodied the fright, passivity, mourning, and beauty traditionally associated with doves.<ref>Hauser A (1985). "Jonah: In Pursuit of the Dove." ''Journal of Biblical Literature'' '''104''' (1): 21–37. {{DOI|10.2307/3260591}}</ref> Birds have themselves been deified, as in the case of the [[Common Peacock]], which is perceived as Mother Earth by the [[Dravidian people|Dravidian]]s of [[India]].<ref>Nair P (1974). "The Peacock Cult in Asia." ''Asian Folklore Studies'' '''33''' (2): 93–170. {{DOI|10.2307/1177550}}</ref> Some birds have also been perceived as monsters, including the mythological [[Roc (mythology)|Roc]] and the [[Māori]]'s legendary ''Pouākai'', a giant bird capable of snatching humans.<ref>Tennyson A, Martinson P (2006). ''Extinct Birds of New Zealand'' Te Papa Press, Wellington ISBN 978-0-909010-21-8</ref> Birds have been featured in culture and art since prehistoric times, when they were represented in early [[cave painting]]s.<ref>Meighan C (1966). "Prehistoric Rock Paintings in Baja California." ''American Antiquity'' '''31''' (3): 372–92. {{DOI|10.2307/2694739}}</ref> Birds were later used in religious or symbolic art and design, such as the magnificent [[Peacock Throne]] of the [[Mughal]] and [[Persian Empire|Persian]] emperors.<ref>Clarke CP (1908). "A Pedestal of the Platform of the Peacock Throne." ''The Metropolitan Museum of Art Bulletin'' '''3''' (10): 182–83. {{DOI|10.2307/3252550}}</ref> With the advent of scientific interest in birds, many paintings of birds were commissioned for books. Among the most famous of these bird artists was [[John James Audubon]], whose paintings of North American birds were a great commercial success in Europe and who later lent his name to the [[National Audubon Society]].<ref>Boime A (1999). "John James Audubon, a birdwatcher's fanciful flights." ''Art History'' '''22''' (5) 728–55. {{DOI|10.1111/1467-8365.00184}}</ref> Birds are also important figures in poetry; for example, [[Homer]] incorporated [[Nightingale]]s into his ''[[Odyssey]]'', and [[Catullus]] used a [[sparrow]] as an erotic symbol in his [[Catullus 2]].<ref>Chandler A (1934). "The Nightingale in Greek and Latin Poetry." ''The Classical Journal'' '''30''' (2): 78–84. </ref> The relationship between an [[albatross]] and a sailor is the central theme of [[Samuel Taylor Coleridge]]'s [[The Rime of the Ancient Mariner]], which led to the use of the [[Albatross (metaphor)|term as a metaphor for a 'burden']].<ref>Lasky E (1992). "A Modern Day Albatross: The Valdez and Some of Life's Other Spills." ''The English Journal'', '''81''' (3): 44–46. {{DOI|10.2307/820195}}</ref> Other [[English language|English]] metaphors derive from birds; [[vulture fund]]s and vulture investors, for instance, take their name from the scavenging vulture.<ref>Carson A (1998). "Vulture Investors, Predators of the 90s: An Ethical Examination." ''Journal of Business Ethics'' '''17''' (5): 543–55. [http://www.springerlink.com/index/W676R8803NL06L38.pdf PDF]</ref> Perceptions of various bird species often vary across cultures. [[Owl]]s are associated with bad luck, [[witchcraft]], and death in parts of [[Africa]],<ref>Enriquez PL, Mikkola H (1997). "Comparative study of general public owl knowledge in Costa Rica, Central America and Malawi, Africa." Pp. 160–66 In: J.R. Duncan, D.H. Johnson, T.H. Nicholls, (Eds). ''Biology and conservation of owls of the Northern Hemisphere. General Technical Report NC-190'', USDA Forest Service, St. Paul, Minnesota. 635 pp.</ref> but are regarded as wise across much of Europe.<ref>Lewis DP (2005). [http://www.owlpages.com/articles.php?section=Owl+Mythology&title=Myth+and+Culture Owls in Mythology and Culture.] The Owl Pages. Retrieved on [[September 15]] [[2007]].</ref> [[Hoopoe]]s were considered sacred in [[Ancient Egypt]] and symbols of virtue in [[Persia]], but were thought of as thieves across much of Europe and harbingers of war in [[Scandinavia]].<ref>Dupree N (1974). "An Interpretation of the Role of the Hoopoe in Afghan Folklore and Magic." ''Folklore'' '''85''' (3): 173–93.</ref> ===Conservation=== [[Image:Albatross hook.jpg|thumb|right|This [[Black-browed Albatross]] has been hooked on a long-line. This type of fishing threatens 19 of the 21 species of albatross, three [[Critically endangered species|critically]] so.]] {{main|Bird conservation}} {{Seealso|Late Quaternary prehistoric birds|Extinct birds}} Though human activities have allowed the expansion of a few species, such as the [[Barn Swallow]] and [[European Starling]], they have caused population decreases or [[extinction]] in many other species. Over a hundred bird species have gone extinct in historical times,<ref>Fuller E (2000). ''Extinct Birds'' (2nd ed.). [[Oxford University Press]], Oxford, New York. ISBN 0-19-850837-9</ref> although the most dramatic human-caused avian extinctions, eradicating an estimated 750–1800 species, occurred during the human colonisation of [[Melanesia]]n, [[Polynesia]]n, and [[Micronesia]]n islands.<ref>Steadman D (2006). ''Extinction and Biogeography in Tropical Pacific Birds'', University of Chicago Press. ISBN 978-0-226-77142-7</ref> Many bird populations are declining worldwide, with 1,221 species listed as [[threatened species|threatened]] by [[Birdlife International]] and the [[IUCN]] in 2007.<ref>[[Birdlife International]] (2007). [http://www.birdlife.org/news/news/2007/05/2007_red_list_update.html 1,221 and counting: More birds than ever face extinction.] Retrieved on [[3 June]] [[2007]].</ref> The most commonly cited human threat to birds is habitat loss.<ref>Norris K, Pain D (eds) (2002). ''Conserving Bird Biodiversity: General Principles and their Application'' Cambridge University Press. ISBN 978-0521789493</ref> Other threats include overhunting, accidental mortality due to [[bird strike|structural collisions]] or [[long-line fishing]] [[bycatch]],<ref>Brothers NP (1991). "Albatross mortality and associated bait loss in the Japanese longline fishery in the southern ocean." ''Biological Conservation'' '''55''': 255–68.</ref> pollution (including oil spills and pesticide use),<ref>Wurster D, Wurster C, Strickland W (1965). "Bird Mortality Following DDT Spray for Dutch Elm Disease." ''Ecology'' '''46''' (4): 488–99. {{DOI|10.1126/science.148.3666.90}}</ref> competition and predation from nonnative [[invasive species]],<ref>Blackburn T, Cassey P, Duncan R, Evans K, Gaston K (2004). "Avian Extinction and Mammalian Introductions on Oceanic Islands." ''[[Science (journal)|Science]]'' '''305''': 1955–58. {{DOI|10.1126/science.1101617}}</ref> and climate change. Governments and [[conservation biology|conservation]] groups work to protect birds, either by passing laws that [[In-situ conservation|preserve]] and [[ecological restoration|restore]] bird habitat or by establishing [[Ex-situ conservation|captive populations]] for reintroductions. Such projects have produced some successes; one study estimated that conservation efforts saved 16 species of bird that would otherwise have gone extinct between 1994 and 2004, including the [[California Condor]] and [[Norfolk Island Green Parrot]].<ref>Butchart S, Stattersfield A, Collar N (2006). "How many bird extinctions have we prevented?" ''Oryx'' '''40''' (3): 266–79 [http://www.birdlife.org/news/news/2006/08/butchart_et_al_2006.pdf PDF]</ref> ==References== <!--This article uses the Cite.php citation mechanism. If you would like more information on how to add references to this article, please see http://meta.wikimedia.org/wiki/Cite/Cite.php--> {{reflist|3}} ==External links== {{portalpar|Birds}} {{Wikispecies|Aves}} {{Wikibookspar|Dichotomous Key|Aves}} {{sisterlinks|Bird}} *[http://www.bsc-eoc.org/avibase/avibase.jsp?lang=EN&pg=home Avibase] – The World Bird Database *[http://www.birdlife.org/ Birdlife International] – Dedicated to bird conservation worldwide; has a database with about 250,000 records on endangered bird species. *[http://people.eku.edu/ritchisong/birdbiogeography1.htm Bird biogeography] *[http://www.audubon.org/bird/index.html Birds and Science] from the [[National Audubon Society]] *[http://www.birds.cornell.edu/ Cornell Lab of Ornithology] *[http://www.stanford.edu/group/stanfordbirds/text/essays/completed_essays.html Essays on bird biology] *[http://www.i-o-c.org/IOComm/index.htm International Ornithological Committee] *[http://www.mrnussbaum.com/birdsindex.htm North American Birds for Kids] *[http://www.ornithology.com/ Ornithology] *[http://elibrary.unm.edu/sora/index.php Sora] Searchable online research archive; Archives of the following ornithological journals [[The Auk]], [[Condor (journal)|Condor]], Journal of Field Ornithology, North American Bird Bander, Studies in Avian Biology, Pacific Coast Avifauna, and [[the Wilson Bulletin]]. *[http://www.hbw.com/ibc/ The Internet Bird Collection] – A free library of videos of the world's birds *[http://www.birdpop.org/ The Institute for Bird Populations, California] {{Footer Birds}} {{Chordata}} {{Archosauromorpha}} {{featured article}} [[Category:Birds| ]] {{Link FA|bg}} {{Link FA|fr}} {{Link FA|hr}} {{Link FA|pl}} [[af:Voël]] [[ar:طائر]] [[an:Aves]] [[frp:Usél]] [[ast:Páxaru]] [[gn:Guyra]] [[ay:Jamach'i]] [[az:Quşlar]] [[zh-min-nan:Chiáu]] [[bar:Fegl]] [[bo:བྱ་]] [[bs:Ptice]] [[bg:Птици]] [[ca:Ocell]] [[cs:Ptáci]] [[cy:Aderyn]] [[da:Fugl]] [[pdc:Voggel]] [[de:Vögel]] [[nv:Tsídii]] [[et:Linnud]] [[es:Aves]] [[eo:Birdoj]] [[eu:Hegazti]] [[fa:پرنده]] [[fo:Fuglur]] [[fr:Oiseau]] [[fy:Fûgels]] [[ga:Éan]] [[gd:Eun]] [[gl:Paxaro]] [[ko:새]] [[hi:पक्षी]] [[hsb:Ptaki]] [[hr:Ptice]] [[io:Ucelo]] [[id:Burung]] [[zu:Inyoni]] [[is:Fugl]] [[it:Aves]] [[he:עופות]] [[jv:Manuk]] [[ka:ფრინველები]] [[kw:Edhen]] [[sw:Ndege (mnyama)]] [[ht:Zwazo]] [[ku:Çûk]] [[la:Aves]] [[lv:Putni]] [[lb:Vullen]] [[lt:Paukščiai]] [[li:Veugel]] [[ln:Ndɛkɛ]] [[hu:Madarak]] [[mk:Птици]] [[mg:Vorona]] [[ml:പക്ഷി]] [[ms:Burung]] [[mn:Шувуу]] [[nah:Tōtōtl]] [[nl:Vogels]] [[nds-nl:Voegel]] [[cr:Pileshish]] [[ja:鳥類]] [[no:Fugler]] [[nn:Fugl]] [[nrm:Ouaîsé]] [[oc:Aves]] [[nds:Vagels]] [[pl:Ptaki]] [[pt:Aves]] [[ro:Pasăre]] [[rm:Utschè]] [[qu:Pisqu]] [[ru:Птицы]] [[sc:Pilloni]] [[stq:Fuugele]] [[scn:Aceddu]] [[simple:Bird]] [[ss:Tinyoni]] [[sk:Vtáky]] [[sl:Ptiči]] [[szl:Ptoki]] [[sr:Птице]] [[sh:Ptica]] [[su:Manuk]] [[fi:Linnut]] [[sv:Fåglar]] [[tl:Ibon]] [[ta:பறவை]] [[te:పక్షి]] [[th:นก]] [[vi:Chim]] [[chr:ᏥᏍᏆ]] [[chy:Ve'kese]] [[tr:Kuşlar]] [[uk:Птахи]] [[vec:Aves]] [[wa:Oujhea]] [[yi:פויגל]] [[zh-yue:雀]] [[zea:Veugels]] [[bat-smg:Paukštē]] [[zh:鸟]]