The Birds Portal
Birds are a group of warm-blooded vertebrates constituting the class Aves, characterized 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 cm (2 in) bee hummingbird to the 2.75 m (9 ft) 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 a group of feathered theropod dinosaurs, and constitute the only 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, but 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.
Selected general bird topic
A rookery is a colony of breeding animals, generally birds. A rookery is generally reserved for a colony of gregarious birds.
While the term rookery may have come from the nesting habits of rooks, it is not reserved for corvids
– northern-European and central-Asian members of the crow family
– nest in prominent colonies (multiple nests) at the tops of trees. Read more...
The antbirds are a large passerine bird family, Thamnophilidae, found across subtropical and tropical Central and South America, from Mexico to Argentina. There are more than 230 species, known variously as antshrikes, antwrens, antvireos, fire-eyes, bare-eyes and bushbirds. They are related to the antthrushes and antpittas (family Formicariidae), the tapaculos, the gnateaters and the ovenbirds. Despite some species' common names, this family is not closely related to the wrens, vireos or shrikes.
Antbirds are generally small birds with rounded wings and strong legs. They have mostly sombre grey, white, brown and rufous plumage, which is sexually dimorphic in pattern and colouring. Some species communicate warnings to rivals by exposing white feather patches on their backs or shoulders. Most have heavy bills, which in many species are hooked at the tip.
Most species live in forests, although a few are found in other habitats. Insects and other arthropods
form the most important part of their diet, although small vertebrates are occasionally taken. Most species feed in the understory
and midstory of the forest, although a few feed in the canopy
and a few on the ground. Many join mixed-species feeding flocks
, and a few species are core members. To various degrees, around eighteen species specialise in following
swarms of army ants
to eat the small invertebrates
flushed by the ants, and many others may feed in this way opportunistically. Read more...
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.
Selected bird anatomy topic
A frontal shield
, also known as a facial shield
or frontal plate
, is a feature of the anatomy of several bird species. Located just above the upper mandible, and protruding along the forehead, it is composed of two main parts: a hard, proteinaceous callus and a soft, fleshy corium. It is thought to play roles in protection, mate identification, sexual selection, and territorial defense. Read more...
, meaning "night parrot", Strigops habroptilus
), also called owl parrot
, is a species
of nocturnal parrot
with finely blotched yellow-green plumage endemic
to New Zealand
. It has a distinct facial disc of sensory, vibrissa-like
feathers, a large grey beak, short legs, large feet, and wings and a tail of relatively short length. A certain combination of traits makes it unique among its kind—it is the world's only flightless parrot, the heaviest parrot, nocturnal, herbivorous, it sports visible sexual dimorphism
in body size, has a low basal metabolic rate
, no male parental care, and is the only parrot to have a polygynous lek
breeding system. It is also possibly one of the world's longest-living birds. Its anatomy typifies the tendency of bird evolution on oceanic islands with few predators and abundant food: accretion of thermodynamic
efficiency at the expense of flight abilities, reduced wing muscles, a diminished keel
on the sternum
and a generally robust physique. Kakapo are critically endangered; only 209 living individuals are known
, all of which have been given names. The ancestral kakapo migrated to the islands of New Zealand in prehistory; in the absence of mammalian
predators, it lost the ability to fly. Because of Polynesian and European colonisation and the introduction of predators such as cats
, and stoats
, most of the kakapo were wiped out. Conservation efforts began in the 1890s, but they were not very successful until the implementation of the Kakapo Recovery Plan in the 1980s. As of November 2005, surviving kakapo are kept on four predator-free islands, Maud
, Chalky (Te Kakahu)
, Codfish (Whenua Hou)
islands, where they are closely monitored. Two large Fiordland islands, Resolution
, have been the subject of large-scale ecological restoration
activities to prepare self-sustaining ecosystems
with suitable habitat for the kakapo. The conservation of the kakapo has made the species well known. Many books and documentaries detailing the plight of the kakapo have been produced in recent years. The kakapo, like many other bird species, has historically been important to the Māori, the indigenous people of New Zealand, appearing in many of the traditional legends and folklore.
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Taxonomy of Aves
|Class Aves, divided into superorders, orders, suborders (where indicated), and families.