The Birds Portal

Birds are a group of warm-blooded vertebrates constituting the class Aves (/ˈvz/), 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 5.5 cm (2.2 in) bee hummingbird to the 2.8 m (9 ft 2 in) common ostrich. There are over 11,000 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 are modified 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. The study of birds is called ornithology.

Birds are feathered theropod dinosaurs and constitute the only known living dinosaurs. Likewise, birds are considered reptiles in the modern cladistic sense of the term, and their closest living relatives are the crocodilians. Birds are descendants of the primitive avialans (whose members include Archaeopteryx) which first appeared during the Late Jurassic. According to recent estimates, modern birds (Neornithes) evolved in the Late Cretaceous and diversified dramatically around the time of the Cretaceous–Paleogene extinction event 66 million years ago, which killed off the pterosaurs and all non-avian dinosaurs.

Many social species pass on knowledge across generations, which is considered a form of culture. 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, and 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. (Full article...)

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African jacana. Extremely long toes and claws help distribute the jacana's weight over a wide area to allow it to walk on floating leaves.

The anatomy of bird legs and feet is diverse, encompassing many accommodations to perform a wide variety of functions.

Most birds are classified as digitigrade animals, meaning they walk on their toes rather than the entire foot. Some of the lower bones of the foot (the distals and most of the metatarsal) are fused to form the tarsometatarsus – a third segment of the leg, specific to birds. The upper bones of the foot (proximals), in turn, are fused with the tibia to form the tibiotarsus, as over time the centralia disappeared. The fibula also reduced. (Full article...)
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Superb lyrebird (Menura novaehollandiae)
A lyrebird is either of two species of ground-dwelling Australian birds that compose the genus Menura, and the family Menuridae. They are most notable for their impressive ability to mimic natural and artificial sounds from their environment, and the striking beauty of the male bird's huge tail when it is fanned out in courtship display. Lyrebirds have unique plumes of neutral-coloured tailfeathers and are among Australia's best-known native birds. (Full article...)
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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.

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Male frigatebird
Gular skin (throat skin), in ornithology, is an area of featherless skin on birds that joins the lower mandible of the beak (or bill) to the bird's neck. Other vertebrate taxa may have a comparable anatomical structure that is referred to as either a gular sac, throat sac, vocal sac or gular fold. (Full article...)
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Male and female superb fairy-wrens
The superb fairy-wren (Malurus cyaneus), also known as superb blue-wren or colloquially as blue wren, is a passerine bird of the family Maluridae. Sedentary and territorial, it is found across southeastern Australia. The male in breeding plumage has a striking bright blue forehead, ear coverts, mantle and tail with a black mask and black or dark blue throat. Non-breeding males, females and juveniles are predominantly grey-brown in colour. Two subspecies are recognised. Like other fairy-wrens, the superb fairy-wren is notable for several peculiar behavioural characteristics; birds are socially monogamous and sexually promiscuous. Male wrens pluck yellow petals and display them to females as part of a courtship display. The superb fairy-wren can be found in almost any area that has at least a little dense undergrowth for shelter. It has adapted well to the urban environment. The superb fairy-wren mainly eats insects and supplements its diet with seeds.


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Taxonomy of Aves

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Sources

  1. ^ Mead, D., ed. (1848). The American Literary Emporium. New York, NY, US: C. H. Camp. p. 209.
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