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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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With forward-facing eyes, the bald eagle has a wide field of binocular vision.

Vision is the most important sense for birds, since good eyesight is essential for safe flight. Birds have a number of adaptations which give visual acuity superior to that of other vertebrate groups; a pigeon has been described as "two eyes with wings". Birds are theropod dinosaurs, and the avian eye resembles that of other sauropsids, with ciliary muscles that can change the shape of the lens rapidly and to a greater extent than in the mammals. Birds have the largest eyes relative to their size in the animal kingdom, and movement is consequently limited within the eye's bony socket. In addition to the two eyelids usually found in vertebrates, bird's eyes are protected by a third transparent movable membrane. The eye's internal anatomy is similar to that of other vertebrates, but has a structure, the pecten oculi, unique to birds.

Some bird groups have specific modifications to their visual system linked to their way of life. Birds of prey have a very high density of receptors and other adaptations that maximise visual acuity. The placement of their eyes gives them good binocular vision enabling accurate judgement of distances. Nocturnal species have tubular eyes, low numbers of colour detectors, but a high density of rod cells which function well in poor light. Terns, gulls, and albatrosses are among the seabirds that have red or yellow oil droplets in the colour receptors to improve distance vision especially in hazy conditions. (Full article...)
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James's flamingos (P. jamesi)

Flamingos or flamingoes /fləˈmɪŋɡz/ are a type of wading bird in the family Phoenicopteridae, which is the only extant family in the order Phoenicopteriformes. There are four flamingo species distributed throughout the Americas (including the Caribbean), and two species native to Afro-Eurasia.

A group of flamingoes is called a "flamboyance". (Full article...)
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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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Grandry corpuscles are found in high numbers in the bills of aquatic birds, such as ducks, where they are believed to play a role in feeding.
The tactile corpuscles of Grandry or Grandry corpuscles are mechanoreceptors found in the beak skin and oral mucosa of aquatic birds. They were first described by Grandry in 1869 in the bill skin of ducks and geese. Their general structure includes the flattened endings of an afferent nerve fiber sandwiched between two or more somewhat flattened sensory cells called Grandry cells, all surrounded by a layer of satellite cells and a partial capsule of collagen protein. Electrophysiological studies have shown that Grandry corpuscles function as rapidly adapting velocity detectors. In birds, Grandry and Merkel corpuscles share many morphological similarities, which has led to some confusion in the literature over their classification (see §Grandry and Merkel corpuscles). (Full article...)
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King vulture
The king vulture, Sarcoramphus papa, is a large Central and South American bird in the New World vulture family Cathartidae. This vulture lives predominantly in tropical lowland forests stretching from southern Mexico to northern Argentina. It is the only surviving member of the genus Sarcoramphus, though fossil members are known. It is large and predominantly white, with gray to black ruff, flight, and tail feathers. Its head and neck are bald, with the skin color varying, including yellow, orange, blue, purple, and red. The king vulture has a very noticeable yellow fleshy carnucle on its beak. This vulture is a scavenger and it often makes the initial cut into a fresh carcass. It also displaces smaller New World vulture species from a carcass. King vultures were popular figures in the Mayan codices as well as in local folklore and medicine. Though currently listed as being of least concern by the IUCN, they are declining in number, due primarily to habitat loss.


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Taxonomy of Aves

Associated Wikimedia

The following Wikimedia Foundation sister projects provide more on this subject:

  • Commons
    Free media repository
  • Wikibooks
    Free textbooks and manuals
  • Wikidata
    Free knowledge base
  • Wikinews
    Free-content news
  • Wikiquote
    Collection of quotations
  • Wikisource
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  • Wikispecies
    Directory of species
  • Wikiversity
    Free learning tools
  • Wikivoyage
    Free travel guide
  • Wiktionary
    Dictionary and thesaurus

Sources

  1. ^ Blake, William (1996). Davis, Mike; Pound, Alan (eds.). Blake: Selected Poems. Oxford, UK: Heinemann Educational Publishers. p. 101. ISBN 0-435150-82-0.
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