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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Deep cup nest of the great reed-warbler

A bird nest is the spot in which a bird lays and incubates its eggs and raises its young. Although the term popularly refers to a specific structure made by the bird itself—such as the grassy cup nest of the American robin or Eurasian blackbird, or the elaborately woven hanging nest of the Montezuma oropendola or the village weaver—that is too restrictive a definition. For some species, a nest is simply a shallow depression made in sand; for others, it is the knot-hole left by a broken branch, a burrow dug into the ground, a chamber drilled into a tree, an enormous rotting pile of vegetation and earth, a shelf made of dried saliva or a mud dome with an entrance tunnel. The smallest bird nests are those of some hummingbirds, tiny cups which can be a mere 2 cm (0.8 in) across and 2–3 cm (0.8–1.2 in) high. At the other extreme, some nest mounds built by the dusky scrubfowl measure more than 11 m (36 ft) in diameter and stand nearly 5 m (16 ft) tall. The study of birds' nests is known as caliology.

Not all bird species build nests. Some species lay their eggs directly on the ground or rocky ledges, while brood parasites lay theirs in the nests of other birds, letting unwitting "foster parents" do the work of rearing the young. Although nests are primarily used for breeding, they may also be reused in the non-breeding season for roosting and some species build special dormitory nests or roost nests (or winter-nest) that are used only for roosting. Most birds build a new nest each year, though some refurbish their old nests. The large eyries (or aeries) of some eagles are platform nests that have been used and refurbished for several years. (Full article...)
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White-browed wagtail (Motacilla maderaspatensis)

The wagtails, longclaws, and pipits are a family, Motacillidae, of small passerine birds with medium to long tails. Around 70 species occur in five genera. The longclaws are entirely restricted to the Afrotropics, and the wagtails are predominantly found in Europe, Africa, and Asia, with two species migrating and breeding in Alaska. The pipits have the most cosmopolitan distribution, being found mostly in the Old World, but occurring also in the Americas and oceanic islands such as New Zealand and the Falklands. Two African species, the yellow-breasted pipit and Sharpe's longclaw, are sometimes placed in a separate seventh genus, Hemimacronyx, which is closely related to the longclaws.

Most motacillids are ground-feeding insectivores of slightly open country. They occupy almost all available habitats, from the shore to high mountains. Wagtails prefer wetter habitats than the pipits. A few species use forests, including the forest wagtail, and other species use forested mountain streams, such as the grey wagtail or the mountain wagtail.

Motacillids take a wide range of invertebrate prey: insects are the most commonly taken, but also including spiders, worms, and small aquatic molluscs and arthropods. All species seem to be fairly catholic in their diets, and the most commonly taken prey for any particular species or population usually reflects local availability. (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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The hyoid apparatus of a horse. A–D: hyoid apparatus (D: basihyoid), E: epiglottis, F: glottis, G–J: cartilages of the trachea.

The hyoid apparatus is the collective term used in veterinary anatomy for the bones which suspend the tongue and larynx. It consists of pairs of stylohyoid, thyrohyoid, epihyoid and ceratohyoid bones, and a single basihyoid bone. The hyoid apparatus resembles the shape of a trapeze, or a bent letter "H". The basihyoid bone lies within the muscle at the base of the tongue.

In humans, the single hyoid bone is an equivalent of the hyoid apparatus. (Full article...)
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Elfin-woods warbler
The elfin-woods warbler (Dendroica angelae, Spanish: reinita de bosque enano), is a bird endemic to the Caribbean island of Puerto Rico where it is a local and uncommon species. It was discovered in 1968 and described in 1972. The species name, angelae, is a tribute to Angela Kepler, one of its discoverers. An insectivore, it feeds by gleaning small insects off leaves. Due to its small populations and restricted habitats, conservation efforts were begun in 1982 to protect this species. The species is not in immediate danger as the majority of its habitat is protected forest, but introduced species, such as rats and mongooses, habitat reduction, and natural disasters represent potential threats to the population.


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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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