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					What are birds

Word Count:
273

Summary:
Birds are warm-blooded, bipedal egg-laying vertebrates that are
characterized primarily by their physical features of feathers, forelimbs
modified as wings, and hollow bones. Birds range largley in size from
tiny hummingbirds all the way up to the huge Ostrich. Depending on how
you look at it, and what your viewpoints are there are approximately ten
thousand different species of living birds. Note the living. there are
several others that have become extinct throughout human history.


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Article Body:
Birds are warm-blooded, bipedal egg-laying vertebrates that are
characterized primarily by their physical features of feathers, forelimbs
modified as wings, and hollow bones. Birds range largley in size from
tiny hummingbirds all the way up to the huge Ostrich. Depending on how
you look at it, and what your viewpoints are there are approximately ten
thousand different species of living birds. Note the living. there are
several others that have become extinct throughout human history. This
mass in numbers makes birds the most diverse class of terrestrial
vertebrates.

Birds are at the majority of times a very differentiated class, with some
feeding on nectar, plants, seeds, insects, rodents, fish, carrion, or
other birds. Most birds are diurnal, which means that they are active
during the day. Some wild birds, such as owls and nightjars, are
nocturnal or crepuscular which means that they are active during the
night. Several birds will migrate long distances to take advantage of
optimal habitats. With that aside there are others that will spend almost
all their time at sea. Some birds have the ability to stay up in the air
for days at a time, even sleeping while in the air.
All birds have similar characterists:
 - Bony beak with no teeth
 - Laying of hard-shelled eggs for reproduction
 - high metabolic rate
 - Light and strong skeleton

Most birds also share the common trait of flight however there are
sevaral species of flightless birds, that exist mostly on islands. These
are birds that once used to have the ability, but do to adaption have
lsost it. A famous flightless bird is the kiwi which exists in New
Zealand.

				
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posted:2/28/2010
language:English
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