Birds, also known as Aves, are a group of endothermic vertebrates, characterised 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. They rank as the world's most numerically-successful class of tetrapods, with approximately ten thousand living species, more than half of these being passerines, sometimes known as perching birds. Birds have wings which are more or less developed depending on the 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 flightless birds, including ratites, penguins, and diverse endemic island species of birds. 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.
Reverse genetic engineering and the fossil record both demonstrate that birds are modern feathered dinosaurs, having evolved from earlier feathered dinosaurs within the theropod group, which are traditionally placed within the saurischian dinosaurs. The closest living relatives of birds are the crocodilians. Primitive bird-like dinosaurs that lie outside class Aves proper, in the broader group Avialae, have been found dating back to the mid-Jurassic period, around 170 million years ago. Many of these early "stem-birds", such as Archaeopteryx, were not yet capable of fully powered flight, and many retained primitive characteristics like toothy jaws in place of beaks, and long bony tails. DNA-based evidence finds that birds diversified dramatically around the time of the Cretaceous-Palaeogene extinction event 66 million years ago, which killed off the pterosaurs and all the non-avian dinosaur lineages. But birds, especially those in the southern continents, survived this event and then migrated to other parts of the world while diversifying during periods of global cooling. This makes them the sole surviving dinosaurs according to cladistics.
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 annually migrate great distances. Birds are social, communicating with visual signals, calls, and bird songs, and participating in such social behaviours as cooperative breeding and hunting, flocking, and mobbing of predators. The vast majority of bird species are socially monogamous (referring to social living arrangement, distinct from genetic monogamy), usually for one breeding season at a time, sometimes for years, but rarely for life. Other species have breeding systems that are polygynous (arrangement of one male with many females) or, rarely, polyandrous (arrangement of 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. Some birds, such as hens, lay eggs even when not fertilised, though unfertilised eggs do not produce offspring.
Many species of birds are economically important as food for human consumption and raw material in manufacturing, with domesticated and undomesticated birds (poultry and game) 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 prominently figure throughout human culture. About 120-130 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...
||But the moment a bird was dead, no matter how beautiful it had been in life, the pleasure of possession became blunted for me.
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
- ...that sexual size dimorphism in the brown songlark is among the most pronounced in any bird, with males as much as 2.3 times heavier than females?
- ...that rufous whistler birds, unlike all other whistler birds, never forage on the ground but high up in trees or other high places?
- ...that the bill of the magpie duck (pictured) becomes green as the bird gets older, and its black crown may go completely white?
Collaboration of the month
Every month a different bird-related topic, article, stub or non-existent article is picked. Please improve the article any way you can.
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Taxonomy of Aves
|Class Aves, divided into superorders, orders, suborders (where indicated), and families.