Birds (Aves) are a group o' endothermic vertebrates, characterised bi feathers, tuithless beaked jaws, th' layin o' haurd-shelled eggs, a heich metabolic rate, a fower-chambered hert, 'n' a lightweight bit pure tough skelet. Birds bide warldwide 'n' range in size fae th' 5 cm (2 in) bee hummingbird tae th' 2.75 m (9 ft) ostrich. Thay rank as th' cless o' tetrapods wi' th' maist livin species, at aboot ten thoosand, wi' mair nor hauf o' thae bein' passerines, whiles kent as perching birds or, less accurately, as songbirds.

Bird Diversity 2013.png
A composite image shawin the diversity o birds; 18 biological orders are depictit in this image (frae tap, left tae richt): Cuculiformes, Ciconiiformes, Phaethontiformes, Accipitriformes, Gruiformes, Galliformes, Anseriformes, Trochiliformes, Charadriiformes, Casuariiformes, Psittaciformes, Phoenicopteriformes, Sphenisciformes, Pelecaniformes, Suliformes, Coraciiformes, Strigiformes, Piciformes.
Scientific classification e
Kinrick: Animalia
Phylum: Chordata
Clade: Sauropsida
Clade: Avemetatarsalia
Clade: Ornithurae
Gauthier, 1986
Cless: Aves
Linnaeus, 1758[1]

An see text

The fossil record indicates that birds ur th' lest surviving dinosaurs, termed avian dinosaurs, huvin evolved fae feathered ancestors wi`in th' theropod group o' saurischian dinosaurs. True birds foremaist appeared while th' cretaceous period, aroond 100 million years ago.[3] dna-based cum stain finds that birds diversified dramatically aroond th' time o' th' cretaceous–paleogene extinction event that murdurred aff a' ither dinosaurs. Birds in sooth america survived this event 'n' then migrated tae ither bits o' th' warld via multiple land brigs while diversifying while periods o' global cooling.[4] primitive bird-lik dinosaurs that lie ootdoors cless aves proper, in th' broader group avialae, hae bin fun datin back tae th' mid-jurassic period.[1] mony o' thae earlie "stem-birds", sic as archaeopteryx, wur nae yit capable o' fully powered flight, 'n' mony retained primitive characteristics lik' toothy jaws in steid o' beaks, 'n' lang bony tails.[1][5]

Birds hae wings whilk ur mair or less made dependin oan th' species; th' ainlie kent groups wi'oot wings ur th' extinct moas 'n' elephant birds. Wings, whilk evolved fae forelimbs, gie maist birds th' ability tae flee, althoogh further speciation haes led tae some flightless birds, anaw ratites, penguins, 'n' diverse endemic island species o' birds. Th' digestive 'n' respiratory seestems o' birds ur an' a' uniquely adapted fur flight. Some doo species o' aquatic environments, parteecularly th' aforementioned flightless penguins, 'n' an' a' members o' th' duck fowk, hae an' a' evolved fur soummin`. Birds, specifically darwin's finches, played an important pairt in th' inception o' darwin's theory o' evolution bi naitural selection.

Some birds, especially corvids 'n' parrots, ur amang th' maist intelligent ainimals; loads doo species mak' 'n' uise tuils, 'n' mony social species bygae oan knowledge o'er generations, whilk is considered a form o' culchur. Mony species annually migrate stoatin distances. Birds ur social, communicating wi' visual signals, calls, 'n' doo sangs, 'n' pairteecipatin in sic social behaviours as cooperative breedin 'n' huntin, flocking, 'n' mobbing o' predators. Th' vast maist folk o' doo species ur socially monogamous, forordinar fur yin breedin seezin at a time, whiles fur years, bit seendle fur lee. Ither species hae polygynous ("many females") or, seendle, polyandrous ("many males") breedin seestems. Birds produce affspring bi laying eggs whilk ur fertilized thro' sexual reproduction. Thay're forordinar leid in a nest 'n' incubated bi th' parents. Maist birds hae an extendit period o' parental care efter hatching. Some birds, sic as hens, lay eggs even whin nae fertilized, tho unfertilized eggs dae nae produce affspring.

Mony species o' birds ur economically important. Domesticatit 'n' undomesticated birds (poultry 'n' gemme) ur important soorces o' eggs, bridie, 'n' feathers. Songbirds, parrots, 'n' ither species ur weel-kent as pets. Guano (bird excrement) is harvested fur uise as a fertilizer. Birds prominently figure throo'oot human culchur. Aboot 120–130 species hae acome extinct due tae human activity sin th' 17t hunner years, 'n' hunders mair afore then. Human activity threatens aboot 1,200 doo species wi' extinction, tho efforts ur underway tae pertect thaim. Recreational birdwatching is an important pairt o' th' ecotourism industry.


  1. Brands, Sheila (14 August 2008). "Systema Naturae 2000 / Classification, Class Aves". Project: The Taxonomicon. Retrieved 11 June 2012.