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Bird Characteristics
The first bird appeared on earth nearly 150 million years ago. Birds
are thought to be the descendants of dinosaurs. Even today birds share some characteristics with reptiles. Unlike other animals,
all birds have feathers. BIrds belong to the class aves.
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Like reptiles, birds are vertebrates. The legs and feet of birds are covered by
thick, dry scales, like those of reptiles. Even the skin around thier beaks is scaly. Birds also have many other characteristics
that set them apart form the rest of the animal kingdom. They have beaks instead of teeth and jaws, and they have feathers,
wings, and many other adaptations for flight.
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Birds need a lot of energy to fly. To get this energy, they have a high metabolism, which generates a lot of body heat.
Because of their high metabolism, birds eat large amounts of food in proportion to their body weight. Some small birds eat
almost constantly to maintain their energy! Most birds eat a high-protien, high-fat diet of insects, nuts, seeds, or meat.
A few birds, such as geese, eat the leaves of plants.
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Birds have two main types of feathers-down feathers and contour feathers. Because feathers wear out, birds shed their
worn feathers and grow new ones. Down feathers are fluffy, insulating feathers
that lie next to a birds body. Contour feathers are made of a stiff
central shaft with many side branches, called barbs. The barbs link together to form a smooth surface.
Bird Facts
There are almost 9,000 species of birds on earth today. Most birds are flyers. Even flightless birds,
such as ostriches, are descendants from ancestors that could fly. Most birds have large eyes and excellent eyesight. This
allows them to see objects and food from a distance. Hawks and eagles can see eight times better than humans! The heart of
a bird beats rapidly. This ensures that the flight muscles get as much oxygen as the blood can carry. In small birds, the
heart beats almost 1,000 times a minute! Your heart beats about 70 times a minute. Bone is a heavy material, but birds have
much lighter skeletons because their bones are hollow.
Kinds of Birds
Animal Planet
National Geographic Kids
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