Birds (class Aves) are feathered, winged, bipedal, endothermic (warm-blooded), egg-laying, vertebrate animals. With around 10,000 living species, they are the most speciose class of tetrapod vertebrates. All present species belong to the subclass Neornithes, and inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from the 5 cm (2 in) Bee Hummingbird to the 2.75 m (9 ft) Ostrich. The fossil record indicates that birds emerged within theropod dinosaurs during the Jurassic period, around 150 million years ago. Paleontologists regard birds as the only clade of dinosaurs to have survived the Cretaceous–Paleogene extinction event 66 million years ago.

Modern birds are characterised by feathers, a beak with no teeth, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a lightweight but strong skeleton. All living species of birds have wings; the most recent species without wings was the moa, which is generally considered to have become extinct in the 16th century. Wings are evolved forelimbs, and most bird species can fly. Flightless birds include ratites, penguins, and a number of diverse endemic island species. Birds also have unique digestive and respiratory systems that are highly adapted for flight. Some birds, especially corvids and parrots, are among the most intelligent animal species; a number of bird species have been observed manufacturing and using tools, and many social species exhibit cultural transmission of knowledge across generations.

Many species undertake long distance annual migrations, and many more perform shorter irregular movements. Birds are social; they communicate using visual signals and through calls and songs, and participate in social behaviours, including cooperative breeding and hunting, flocking, and mobbing of predators. The vast majority of bird species are socially monogamous, usually for one breeding season at a time, sometimes for years, but rarely for life. Other species have polygynous ("many females") or, rarely, polyandrous ("many males") breeding systems. Eggs are usually laid in a nest and incubated by the parents. Most birds have an extended period of parental care after hatching.

Many species are of economic importance, mostly as sources of food acquired through hunting or farming. Some species, particularly songbirds and parrots, are popular as pets. Other uses include the harvesting of guano (droppings) for use as a fertiliser. Birds figure prominently in all aspects of human culture from religion to poetry to popular music. About 120–130 species have become extinct as a result of human activity since the 17th century, and hundreds more before then. Currently about 1,200 species of birds are threatened with extinction by human activities, though efforts are underway to protect them.

Read more about Roost:  Evolution and Taxonomy, Distribution, Anatomy and Physiology, Behaviour, Ecology, Relationship With Humans

Other articles related to "roost":

Lesser Short-nosed Fruit Bat - Behavior
... Lesser short-nosed fruit bats prefer to roost in small groups in trees, under leaves, and in caves ... Young males may roost alone ... It is common for one male to roost with up to four females ...
Jimmy Jones (pianist) - Discography - As Sideman
... Stitt New York Jazz (Verve, 1956) The Saxophones of Sonny Stitt (Roost, 1958) A Little Bit of Stitt (Roost, 1959) The Sonny Side of Stitt (Roost, 1959) Stittsville (Roost, 1960) Sonny Side Up (Roos ...
Bugle Rock - Fruit Bats
... of Threatened Species Chiroptera Specialist Group 1996) have been recorded in roost trees (Ficus sp ... in the garden, tree groups and protected areas with a roost size of 650–710 ... The roost trees, about 20–25 and generally 30–40 feet (9.1–12.2 m) tall, are in the central area of the park and are 50–60 years old ...
Roost - Relationship With Humans - Conservation
... The most commonly cited human threat to birds is habitat loss ... Other threats include overhunting, accidental mortality due to structural collisions or long-line fishing bycatch, pollution (including oil spills and pesticide use), competition and predation from nonnative invasive species, and climate change ...
Buzzard Roost, Alabama - History
... Levi Colbert, Chickasaw Bench Chief built his stand in Buzzard Roost in 1801, and he ran an inn with his family ... He is credited with changing the name from Buzzard Sleep to Buzzard Roost ... Buzzard Roost Covered Bridge, built over Buzzard Roost Creek in 1860, was 94 ft ...

Famous quotes containing the word roost:

    “Our snowstorms as a rule
    Aren’t looked on as man-killers, and although
    I’d rather be the beast that sleeps the sleep
    Under it all, his door sealed up and lost,
    Than the man fighting it to keep above it,
    Yet think of the small birds at roost and not
    In nests....”
    Robert Frost (1874–1963)