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Birds
(Class Aves)
The
first birds appeared on Earth about 150 million years ago, and most of
the birds you'll find today have been around for at least 40 million
years. Currently, there are
8,500 different species (kinds) of birds.
Birds can be very large, like an ostrich, or very small, like a
hummingbird, or just about any size in between. Birds
are vertebrate animals—that means they have a backbone.
They breathe air and are warm-blooded, so their internal body
temperature stays pretty much the same all year long.
Birds are the only animals that have feathers.
All birds have wings, but not every bird can fly. In
order to fly, a bird needs a very special kind of body.
Birds usually don't weigh very much for their size.
Their bones have cavities filled with air, and heavy jawbones and
teeth are replaced by a strong, lightweight beak.
The power for flight comes from very strong muscles attached to
the enlarged breastbone. All
birds begin their life in an egg. The
parent bird incubates (keeps warm) the egg as the young bird inside
develops. Some baby birds
are naked and blind when they hatch.
These babies stay in their nest, fed and protected by their
parents, until they are old enough to learn how to fly.
Other baby birds have downy feathers when they hatch.
As soon as these chicks dry they can follow their parents out of
the nest on foot. They
won't learn to fly until they grow new feathers to replace the downy
ones. Fast
Facts:
Bird
Diversity Birds
are divided up into groups of related animals, called Orders.
Below you'll find the name of the most common orders and some
examples.
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