Birds are a group of warm-blooded vertebrates constituting the class Aves (Latin: [ˈaveːs]), 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 and they are split into 44 orders. More than half 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 some estimates, modern birds (Neornithes) evolved in the Late Cretaceous or between the Early and Late Cretaceous (100 Ma) and diversified dramatically around the time of the Cretaceous–Paleogene extinction event 66 million years ago, which killed off the pterosaurs and all non-ornithuran dinosaurs.
Many social species preserve knowledge across generations (culture). Birds are social, communicating with visual signals, calls, and songs, and participating in such behaviour 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...)
Bird food plants are certain trees, shrubs and herbaceous plants bearing fruits which afford food for birds. These have been discovered by observation, and by the scientific examination of the contents of birds' stomachs. By planting those species, therefore, which have been proved most desirable and that are suited to the climate and soil of the chosen location, birds can be attracted to the vicinity of dwelling houses or to any other desired spot as a copse or shrubbery, or, on the other hand, lured away from valuable orchards, since they appear to like best arid, bitter, sour or aromatic fruits, distasteful to human beings, even better than the cultivated kinds.
Many of these bird-attracting plants are ornamental as well, since many have pretty fruits, red in color and often clinging to their branches far into the winter, furnishing grateful additions to the meager fare of hard-weather birds. (Full article...)
Estrildidae, or estrildid finches, is a family of small seed-eating passerine birds of the Old World tropics and Australasia. They comprise species commonly known as munias, mannikins, firefinches, parrotfinches and waxbills.
They are gregarious and often colonial seed eaters with short, thick, but pointed bills. They are all similar in structure and habits, but vary widely in plumage colours and patterns.
All estrildids build large, domed nests and lay five to ten white eggs. Many species build roost nests. Some of the firefinches and pytilias are hosts to the brood-parasitic indigobirds and whydahs, respectively. (Full article...)
Anatomy: Anatomy • Skeleton • Flight • Eggs • Feathers • Plumage
Evolution and extinction: Evolution • Archaeopteryx • Hybridisation • Late Quaternary prehistoric birds • Fossils • Taxonomy • Extinction
Behaviour: Singing • Intelligence • Migration • Reproduction • Nesting • Incubation • Brood parasites
Bird orders: Struthioniformes • Tinamiformes • Anseriformes • Accipitriformes • Galliformes • Gaviiformes • Podicipediformes • Procellariiformes • Sphenisciformes • Pelecaniformes • Ciconiiformes • Phoenicopteriformes • Falconiformes • Gruiformes • Charadriiformes • Pteroclidiformes • Columbiformes • Psittaciformes • Cuculiformes • Strigiformes • Caprimulgiformes • Apodiformes • Coraciiformes • Piciformes • Trogoniformes • Coliiformes • Passeriformes
Bird lists: Families and orders • Lists by region
Birds and humans: Ringing • Ornithology • Bird collections • Birdwatching • Birdfeeding • Conservation • Aviculture
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.
Delayed-feathering in chickens is a genetically determined delay in the first weeks of feather growing, which occurs normally among the chicks of many chicken breeds and no longer manifests itself once the chicken completes adult plumage.
The difference between fast normal feather development and delayed-feathering can be recognized in one-day-old chicks but is always more evident in 10- to 12-day-old chicks. (Full article...)
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Class Aves, divided into superorders, orders, suborders (where indicated), and families. | ||||
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