Portal:Birds

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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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The evolution of birds began in the Jurassic Period, with the earliest birds derived from a clade of theropod dinosaurs named Paraves. Birds are categorized as a biological class, Aves. For more than a century, the small theropod dinosaur Archaeopteryx lithographica from the Late Jurassic period was considered to have been the earliest bird. Modern phylogenies place birds in the dinosaur clade Theropoda. According to the current consensus, Aves and a sister group, the order Crocodilia, together are the sole living members of an unranked reptile clade, the Archosauria. Four distinct lineages of bird survived the Cretaceous–Paleogene extinction event 66 million years ago, giving rise to ostriches and relatives (Palaeognathae), waterfowl (Anseriformes), ground-living fowl (Galliformes), and "modern birds" (Neoaves). Phylogenetically, Aves is usually defined as all descendants of the most recent common ancestor of a specific modern bird species (such as the house sparrow, Passer domesticus), and either Archaeopteryx, or some prehistoric species closer to Neornithes (to avoid the problems caused by the unclear relationships of Archaeopteryx to other theropods). If the latter classification is used then the larger group is termed Avialae. Currently, the relationship between dinosaurs, Archaeopteryx, and modern birds is still under debate. (Full article...)
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Great crested grebe (Podiceps cristatus)

Grebes (/ˈɡrbz/) are aquatic diving birds in the order Podicipediformes /ˌpɒdɪsɪˈpɛdɪfɔːrmz/. Grebes are widely distributed freshwater birds, with some species also found in marine habitats during migration and winter. Most grebes fly, although some flightless species exist, most notably in stable lakes. The order contains a single family, the Podicipedidae, which includes 22 species in six extant genera.

Although, superficially, they resemble other diving birds such as loons and coots, they are most closely related to flamingos, as supported by morphological, molecular and paleontological data. Many species are monogamous and are known for their courtship displays, with the pair performing synchronized dances across the water's surface. The birds build floating vegetative nests where they lay several eggs. About a third of the world's grebes are listed at various levels of conservation concerns—the biggest threats including habitat loss, the introduction of invasive predatory fish and human poaching. As such, three species have gone extinct. (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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This stylised bird skeleton highlights the uncinate processes

The uncinate processes of the ribs are extensions of bone that project caudally from the vertical segment of each rib. (Uncinate means hooked from Latin uncinatus, from uncinus, barb, from uncus, hook.) They are found in birds (except for screamers), reptiles, and the early amphibian Ichthyostega.

These processes can serve to attach scapula muscles, and help to strengthen the rib cage overlapping with the rib behind them. They are also shown to have a role in respiration by increasing the effectiveness of muscles involved in inspiration including the appendicocostal muscles. The processes are short in walking birds and long in diving species and are of intermediate length in non-specialist birds. The screamers (Anhimidae) are unique in lacking this process. The process has also been noted in some enantiornitheans. Although among living vertebrates, bony uncinate processes are unique to birds, cartilaginous uncinate processes are present in crocodiles. The uncinate process has also been reported in Sphenodon and fossil vertebrates including Caudipteryx, oviraptorids, dromaeosaurids, Confuciusornis, Chaoyangia, and Longipteryx; however it apparently does not occur in Archaeopteryx, though Codd et al. (2007) reported uncinate processes in Archaeopteryx. (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.


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?

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Taxonomy of Aves

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Sources

  1. ^ Woods, R.L. (1967). The Modern Handbook of Humor. McGraw-Hill. p. 30. Retrieved February 7, 2020.
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