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
Vision is the most important sense for birds, since good eyesight is essential for safe flight, and this group has a number of adaptations which give visual acuity superior to that of other vertebrate groups; a pigeon has been described as "two eyes with wings". The avian eye resembles that of a reptile, with ciliary muscles that can change the shape of the lens rapidly and to a greater extent than in the mammals. Birds have the largest eyes relative to their size in the animal kingdom, and movement is consequently limited within the eye's bony socket. In addition to the two eyelids usually found in vertebrates, it is protected by a third transparent movable membrane. The eye's internal anatomy is similar to that of other vertebrates, but has a structure, the pecten oculi, unique to birds.
Some bird groups have specific modifications to their visual system linked to their way of life. Birds of prey
have a very high density of receptors and other adaptations that maximise visual acuity. The placement of their eyes gives them good binocular vision enabling accurate judgement of distances. Nocturnal
species have tubular eyes, low numbers of colour detectors, but a high density of rod cells which function well in poor light. Terns
are amongst the seabirds
which have red or yellow oil droplets
in the colour receptors to improve distance vision especially in hazy conditions. Read more...
Woodpeckers are part of the family Picidae, that also includes the piculets, wrynecks, and sapsuckers. Members of this family are found worldwide, except for Australia, New Guinea, New Zealand, Madagascar, and the extreme polar regions. Most species live in forests or woodland habitats, although a few species are known that live in treeless areas, such as rocky hillsides and deserts, and the Gila woodpecker specialises in exploiting cacti.
Members of this family are chiefly known for their characteristic behaviour. They mostly forage for insect prey on the trunks and branches of trees, and often communicate by drumming with their beak, producing a reverberatory sound that can be heard at some distance. Some species vary their diet with fruits, birds' eggs, small animals, and tree sap, human scraps, and carrion. They mostly nest and roost in holes that they excavate in tree trunks, and their abandoned holes are of importance to other cavity-nesting birds. They sometimes come into conflict with humans when they make holes in buildings or feed on fruit crops, but perform a useful service by their removal of insect pests on trees.
The Picidae are one of nine living families in the order Piciformes
, the others being barbets
(comprising three families), toucans
, toucan-barbets, and honeyguides
which (along with woodpeckers) comprise the clade Pici
, and the jacamars
in the clade Galbuli
. DNA sequencing
has confirmed the sister relationships
of these two groups. The family Picidae includes about 240 species
arranged in 35 genera
. Almost 20 species are threatened with extinction
due to loss of habitat or habitat fragmentation
, with one, the Bermuda flicker
, being extinct and a further two possibly being so. 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
External anatomy (topography
) of a typical bird: 1 beak
, 2 head
, 3 iris
, 4 pupil
, 5 mantle
, 6 lesser coverts
, 7 scapulars
, 8 coverts
, 9 tertials
, 10 rump
, 11 primaries
, 12 vent
, 13 thigh
, 14 tibio-tarsal articulation
, 15 tarsus
, 16 feet
, 17 tibia
, 18 belly
, 19 flanks
, 20 breast
, 21 throat
, 22 chin
, 23 eyestripe
The following is a glossary of common English language terms used in the description of birds—warm-blooded vertebrates of the class Aves, characterized by feathers, the ability to fly in all but the approximately 60 extant species of flightless birds, toothless, beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart and a strong yet lightweight skeleton.
Among other details such as size, proportions and shape, terms defining bird features developed and are used to describe features unique to the class—especially evolutionary adaptations that developed to aid flight
. There are, for example, numerous terms describing the complex structural makeup of feathers (e.g., barbules
, and vanes
); types of feathers (e.g., filoplume
, and plumulaceous
feathers); and their growth and loss (e.g., colour morph
, nuptial plumage
, and pterylosis
). Read more...
The splendid fairy-wren
), also known simply as the splendid wren
or more colloquially in Western Australia
as the blue wren
, is a passerine
bird of the family Maluridae
. It is found across much of the Australian continent from central-western New South Wales
and southwestern Queensland
over to coastal Western Australia. The male in breeding plumage is a small, long-tailed bird of predominantly bright blue and black colouration. Non-breeding males, females and juveniles are predominantly grey-brown in colour. It comprises several similar all-blue and black subspecies that were originally considered separate species. Like other fairy-wrens, the splendid fairy-wren is notable for several peculiar behavioural characteristics; birds are socially monogamous
and sexually promiscuous
. Male wrens pluck pink or purple petals and display them to females as part of a courtship display. The habitat of the splendid fairy-wren ranges from forest to dry scrub, generally with ample vegetation for shelter. It has not adapted well to human occupation of the landscape and has disappeared from some urbanized areas. The splendid fairy-wren mainly eats insects and supplements its diet with seeds.
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Taxonomy of Aves
|Class Aves, divided into superorders, orders, suborders (where indicated), and families.
- ^ Pennsylvania. Dept. of Common Schools; Pennsylvania State Education Association (1911). Pennsylvania School Journal. Pennsylvania State Education Association. p. 115. Retrieved February 7, 2020.