Birds are a group of warm-bloodedvertebrates constituting the classAves, 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.
Some birds, especially corvids and parrots, are among the most intelligent animals; several bird species make and use tools, with certain birds' use of tools rivaling the best performances of primates. 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.
A bird observatory is a centre for the study of bird migration and birdpopulations. They are usually focused on local birds, but may also include interest in far-flung areas. Most bird observatories are small operations with a limited staff, many volunteers and a not-for-profit educational status. Many bird observatories conduct bird ringing or bird banding (term in the United States). Read more...
Feathers are one of the epidermal growths that form the distinctive outer covering, or plumage, of birds. They are the outstanding characteristic that distinguishes the class Aves from all other living groups.
The superb fairy-wren (Malurus cyaneus), also known as superb blue-wren or colloquially as blue wren, is a passerine bird of the Maluridae family. Sedentary and territorial, it is found across south-eastern 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.