The Basics About Birds
A bird is a warm-blooded, bipedal, egg-laying vertebrate, containing
feathers, wings and hollow bones.
The size of birds ranges from a small humming bird to a large ostrich and emu.
The characteristics of birds include no teeth, bony beak, high metabolism and
strong skeletons. They lay hard shelled eggs.
It is estimate that there are 8,800,010,200 living species of birds and another
120,130 that have become extinct throughout human history. This makes birds the
most varied class of vertebrates in the world.
Birds feed on different items including nectar, plants, and seeds, as well as
insects, rodents, fish or even other birds.
Most birds are active during the day, although you will find a few such as owls
and nightjars that are active during the night or twilight hours (nocturnal).
Many species of birds migrate in the winter in order to get away from the
extremely cold temperatures. Other birds may spend their time at sea. Some birds
can even sleep while flying.
Of course, most birds can fly, but there are those species such as the penguins,
ostrich, emu and kiwi, which are flightless. The flightless birds are more prone
to becoming extinct as humans or mammals take over their habitat. |
