Map showing the distribution of the Birds taxa The shading illustrates the diversity of this group - the darker the colour the greater the number of species. Data provided by WWF's Wildfinder. Explore this group Whooper swan and mallard ducks on the edge of a lakeDucks, geese and swans (family) A small flock of Alpine swifts in flightSwifts and hummingbirds Female nightjar on nestNightjar (species) Black-legged kittiwakes at a clifftop colonyShorebirds Four American wood ibis in flightStorks and long-legged wading birds Wood pigeon walking in an urban parkPigeons and doves (family) A family of pied kingfishers perched along a branchKingfishers and hornbills Adult male cuckoo in flightCommon cuckoo (species) Yellow-billed kites chasing each otherBirds of prey A male red grouse amongst grassGamebirds Two divers on a lake at sunsetDivers (genus) Common cranes calling with heads raised in the airCoots, cranes and rails A group of finches sitting on a couple of branchesPerching birds Gannets in flight, following a fishing boat to look for fishPelicans, cormorants and gannets A large flock of lesser flamingos feeding on a lakeFlamingos (genus) Male and female great spotted woodpeckers in winterWoodpeckers (family) Courting pair of great crested grebes on a lakeGrebes (family) A small group of wandering albatrosses displaying during the mating seasonTubenoses Scarlet macaws amongst the treesParrots A very large king penguin colonyPenguins (family) Four spotted owl youngsters perched on a branchOwls Several domestic ostrich in South AfricaOstriches and rheas The extinct flightless elephant bird lived in Madagascar until around the 16th century.Elephant birds (family) Prehistoric life All Prehistoric Birds Archaeopteryx perched on branch of conifer tree, with wings spread openArchaeopteryx (genus) The giant bird Gastornis hunting a Leptictidium in dense forestGastornis (genus) Terror bird with preyTerror birds (family) Bird size range A graphic illustration comparing the size of bird with humans, from largest to smallest: moa, ostrich, Gastornis, human, flamin A comparison of bird size in relation to humans - from the 3.7m tall moa to the 12cm high robin. About Birds (class Aves) are feathered, winged, bipedal, endothermic (warm-blooded), egg-laying, vertebrate animals. With around 10,000 living species, they are the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from the 5 cm (2 in) Bee Hummingbird to the 2.75 m (9 ft) Ostrich. The fossil record indicates that birds evolved from theropod dinosaurs during the Jurassic period, around 160 million years (Ma) ago. Paleontologists regard birds as the only clade of dinosaurs to have survived the Cretaceous–Paleogene extinction event 65.5 Ma ago. Modern birds are characterised by feathers, a beak with no teeth, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a lightweight but strong skeleton. All living species of birds have wings—the now extinct flightless Moa of New Zealand was the only exception. Wings are evolved forelimbs, and most bird species can fly, with some exceptions, including ratites, penguins, and a number of diverse endemic island species. Birds also have unique digestive and respiratory systems 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 migrations, and many more perform shorter irregular movements. Birds are social; they communicate using visual signals and through calls and songs, and participate in social behaviours, including cooperative breeding and hunting, flocking, and 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 polygynous ("many females") or, rarely, polyandrous ("many males") breeding systems. Eggs are usually laid in a nest and 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 songbirds and parrots, are popular as pets. Other uses include the harvesting of guano (droppings) for use as a fertiliser. Birds figure prominently in all aspects of human culture from religion to poetry to popular music. About 120–130 species have become 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 protect them. Read more at Wikipedia This entry is from Wikipedia, the user-contributed encyclopedia. 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