Birds
Birds are bipedal, warm-blooded, oviparous vertebrate animals characterized mainly by feathers, forelimbs modified as wings, and (in most) hollow bones.
Birds range in size from the tiny hummingbirds to the huge Ostrich and Emu. Depending on the taxonomic viewpoint, there are about 8,800–10,200 living bird species (and about 120–130 that have become extinct in the span of human history) in the world, making them the mainly diverse class of terrestrial vertebrates.
Birds feed on nectar, plants, seeds, insects, fish, mammals, carrion, or other birds.
Most birds are diurnal, or active during the day, but some birds, such as the owls and nightjars, are nocturnal or crepuscular (active during twilight hours), and lots of coastal waders feed when the tides are appropriate, by day or night.
Many birds migrate long distances to utilize optimum habitats (e.g., Arctic Tern) while others spend approximately all their time at sea (e.g. the Wandering Albatross). Some, such as Common Swifts, stay aloft for days at a time, even sleeping on the wing.
Common characteristics of birds include a bony beak with no teeth, the laying of hard-shelled eggs, high metabolic rate, a 4-chambered heart, and a light but strong skeleton. Most birds are characterized by flight, though the ratites are flightless, and several other species, particularly on islands, have also lost this ability. Flightless birds include the penguins, ostrich, kiwi, and the extinct Dodo. Flightless species are vulnerable to extinction when humans or the mammals they initiate arrive in their habitat. The Great Auk, flightless rails, and the moa of New Zealand, for example, all became extinct due to human influence.
Birds are among the most widely studied of all animal groups. Hundreds of academic journals and thousands of scientists are devoted to bird research, while amateur enthusiasts (called birdwatchers, twitches or, more commonly, birders) probably number in the millions.
Birds range in size from the tiny hummingbirds to the huge Ostrich and Emu. Depending on the taxonomic viewpoint, there are about 8,800–10,200 living bird species (and about 120–130 that have become extinct in the span of human history) in the world, making them the mainly diverse class of terrestrial vertebrates.
Birds feed on nectar, plants, seeds, insects, fish, mammals, carrion, or other birds.
Most birds are diurnal, or active during the day, but some birds, such as the owls and nightjars, are nocturnal or crepuscular (active during twilight hours), and lots of coastal waders feed when the tides are appropriate, by day or night.
Many birds migrate long distances to utilize optimum habitats (e.g., Arctic Tern) while others spend approximately all their time at sea (e.g. the Wandering Albatross). Some, such as Common Swifts, stay aloft for days at a time, even sleeping on the wing.
Common characteristics of birds include a bony beak with no teeth, the laying of hard-shelled eggs, high metabolic rate, a 4-chambered heart, and a light but strong skeleton. Most birds are characterized by flight, though the ratites are flightless, and several other species, particularly on islands, have also lost this ability. Flightless birds include the penguins, ostrich, kiwi, and the extinct Dodo. Flightless species are vulnerable to extinction when humans or the mammals they initiate arrive in their habitat. The Great Auk, flightless rails, and the moa of New Zealand, for example, all became extinct due to human influence.
Birds are among the most widely studied of all animal groups. Hundreds of academic journals and thousands of scientists are devoted to bird research, while amateur enthusiasts (called birdwatchers, twitches or, more commonly, birders) probably number in the millions.
posted by puffaloonie at
6:12 PM
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