Birds are a group of warm-blooded vertebrates constituting the class Aves, characterized by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweight skeleton. Birds live worldwide and range in size from the 5 cm (2 in) bee hummingbird to the 2.75 m (9 ft) ostrich. There are about ten thousand living species, more than half of which are passerine, or "perching" birds. Birds have wings whose development varies according to species; the only known groups without wings are the extinct moa and elephant birds. Wings, which evolved from forelimbs, gave birds the ability to fly, although further evolution has led to the loss of flight in some birds, including ratites, penguins, and diverse endemic island species. The digestive and respiratory systems of birds are also uniquely adapted for flight. Some bird species of aquatic environments, particularly seabirds and some waterbirds, have further evolved for swimming.
Birds are a group of feathered theropod dinosaurs, and constitute the only living dinosaurs. Likewise, the closest living relatives of birds are the crocodilians. Birds are descendants of the primitive avialans (whose members include Archaeopteryx) which first appeared about 160 million years ago (mya) in China. According to DNA evidence, modern birds (Neornithes) evolved in the Middle to Late Cretaceous, and diversified dramatically around the time of the Cretaceous-Paleogene extinction event 66 mya, which killed off the pterosaurs and all non-avian dinosaurs.
Some birds, especially corvids and parrots, are among the most intelligent animals; several bird species make and use tools, and many social species pass on knowledge across generations, which is considered a form of culture. Many species migrate annually over great distances. Birds are social, communicating with visual signals, calls, and songs, and participating in such behaviours as cooperative breeding and hunting, flocking, and mobbing of predators. The vast majority of bird species are socially (but not necessarily sexually) monogamous, usually for one breeding season at a time, sometimes for years, but rarely for life. Other species have breeding systems that are polygynous (one male with many females) or, rarely, polyandrous (one female with many males). Birds produce offspring by laying eggs which are fertilised through sexual reproduction. They are usually laid in a nest and incubated by the parents. Most birds have an extended period of parental care after hatching.
Many species of birds are economically important as food for human consumption and raw material in manufacturing, with domesticated and undomesticated birds being important sources of eggs, meat, and feathers. Songbirds, parrots, and other species are popular as pets. Guano (bird excrement) is harvested for use as a fertiliser. Birds figure throughout human culture. About 120 to 130 species have become extinct due to human activity since the 17th century, and hundreds more before then. Human activity threatens about 1,200 bird species with extinction, though efforts are underway to protect them. Recreational birdwatching is an important part of the ecotourism industry.
Selected general bird topic
, Limosa fedoa
, prepared as a skin (shmoo
), skeleton, and spread wing
Bird collections are curated repositories of scientific specimens consisting of birds and their parts. They are a research resource for ornithology, the science of birds, and for other scientific disciplines in which information about birds is useful. These collections are archives of avian diversity and serve the diverse needs of scientific researchers, artists, and educators.
Collections may include a variety of preparation types emphasizing preservation of feathers, skeletons, soft tissues, or (increasingly) some combination thereof. Modern collections range in size from small teaching collections, such as one might find at a nature reserve visitor center or small college, to large research collections of the world's major natural history museums, the
largest of which contain hundreds of thousands of specimens. Bird collections function much like libraries, with specimens arranged in drawers and cabinets in taxonomic order, curated by scientists who oversee the maintenance, use, and growth of collections and make them available for study through visits or loans. Read more...
Free online resources:
There is also Birds of North America, Cornell University's massive project collecting information on every breeding bird in the ABA area. It is available for US$40 a year.
For more sources, including printed sources, see WikiProject Birds.
Selected bird anatomy topic
The hyperpallium (formerly called the hyperstriatum or the Wulst) is the destination for lemnothalamic projections in birds. The projections as well as the granular cells at the destination of the lemnothalamic projections to the hyperpallium are similar in morphology, electrophysiology, retinotopic organization, and columnar organization to the striate cortex in mammals. These avian granular cells are thought to have evolved independently in birds, as they do not appear in reptiles.
The projections originate in the dorsal lateral geniculate nucleus and target three layers in the hyperpallium: the hyperpallium intercalatum, the hyperpallium densocellularis, and the nucleus interstitialis hyperpalii apicalis, with the densest projections being to the later two layers. Read more...
The splendid fairy-wren
), also known simply as the splendid wren
or more colloquially in Western Australia
as the blue wren
, is a passerine
bird of the Maluridae
family. It is found across much of the Australian continent from central-western New South Wales
and southwestern Queensland
over to coastal Western Australia. The male in breeding plumage is a small, long-tailed bird of predominantly bright blue and black colouration. Non-breeding males, females and juveniles are predominantly grey-brown in colour. It comprises several similar all-blue and black subspecies that were originally considered separate species. Like other fairy-wrens, the splendid fairy-wren is notable for several peculiar behavioural characteristics; birds are socially monogamous
and sexually promiscuous
. Male wrens pluck pink or purple petals and display them to females as part of a courtship display. The habitat of the splendid fairy-wren ranges from forest to dry scrub, generally with ample vegetation for shelter. It has not adapted well to human occupation of the landscape and has disappeared from some urbanized areas. The splendid fairy-wren mainly eats insects and supplements its diet with seeds.
Did you know
Things you can do
Taxonomy of Aves
|Class Aves, divided into superorders, orders, suborders (where indicated), and families.