Portal:Birds

The Birds Portal

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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) 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 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 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.

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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The distance A to B is the wingspan of this Boeing 777-200ER

The wingspan (or just span) of a bird or an airplane is the distance from one wingtip to the other wingtip. For example, the Boeing 777–200 has a wingspan of 60.93 metres (199 ft 11 in), and a wandering albatross (Diomedea exulans) caught in 1965 had a wingspan of 3.63 metres (11 ft 11 in), the official record for a living bird. The term wingspan, more technically extent, is also used for other winged animals such as pterosaurs, bats, insects, etc., and other aircraft such as ornithopters.

In humans, the term wingspan also refers to the arm span, which is distance between the length from one end of an individual's arms (measured at the fingertips) to the other when raised parallel to the ground at shoulder height at a 90º angle. Former professional basketball player Manute Bol stood at 7 ft 7 in (2.31 m) and owned one of the largest wingspans at 8 ft 6 in (2.59 m). (Full article...)
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Bananaquits.jpg
The bananaquit (Coereba flaveola) is a species of passerine bird in the tanager family Thraupidae. Before the development of molecular genetics in the 21st century, its relationship to other species was uncertain and it was either placed with the buntings and New World sparrows in the family Emberizidae, with New World warblers in the family Parulidae or in its own monotypic family Coerebidae. This small, active nectarivore is found in warmer parts of the Americas, and is generally common. (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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Cloaca of a Red-tailed hawk

In animal anatomy, a cloaca (/klˈkə/ kloh-AY-kə), plural cloacae (/klˈsi/ kloh-AY-see or /klˈki/ kloh-AY-kee), is the posterior orifice that serves as the only opening for the digestive, reproductive, and urinary tracts (if present) of many vertebrate animals. All amphibians, reptiles, birds, and a few mammals (monotremes, tenrecs, golden moles, and marsupial moles) have this orifice, from which they excrete both urine and feces; this is in contrast to most placental mammals, which have two or three separate orifices for evacuation. Excretory openings with analogous purpose in some invertebrates are also sometimes referred to as cloacae. Mating through the cloaca is known as cloacal copulation, commonly referred to as cloacal kiss.

The cloacal region is also often associated with a secretory organ, the cloacal gland, which has been implicated in the scent-marking behavior of some reptiles, marsupials, amphibians, and monotremes. (Full article...)
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Common raven
The common raven (Corvus corax), also known as the northern raven, is a large all-black passerine bird in the crow family. Found across the #Northern Hemisphere, it is the most widely distributed of all corvids. There are eight known subspecies. It is one of the two largest corvids, and is possibly the heaviest passerine bird. common ravens typically live about 10 to 15 years in the wild, although lifespans of up to 40 years have been recorded. Young birds may travel in flocks, but later mate for life, with each mated pair defending a territory. The common raven has coexisted with humans for thousands of years. Part of its success comes from its omnivorous diet; common ravens are extremely versatile and opportunistic in finding sources of nutrition, feeding on carrion, insects and food waste, in addition to cereal grains, berries, fruit and small animals. Some remarkable feats of problem-solving have been observed in the species, leading to the belief that it is highly intelligent. Over the centuries, it has been the subject of mythology, folklore, art and literature in many cultures.


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Taxonomy of Aves

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Sources

  1. ^ Damon, S.F.; Eaves, M. (1988). A Blake Dictionary: The Ideas and Symbols of William Blake. Reference: Literary Criticism. Brown University Press. p. 112. ISBN 978-0-87451-436-0. Retrieved February 7, 2020.
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