Birds Infos

Birds live worldwide and range in size from the 5.5 cm (2.2 in) bee hummingbird to the 2.8 m (9 ft 2 in) ostrich.
There are about ten thousand living species, more than half of which are passerine, or \"perching\" birds. Birds have wings whose development varies according to species; the only known groups without wings are the extinct moa and elephant birds.
Wings, which evolved from forelimbs, gave birds the ability to fly, although further evolution has led to the loss of flight in some birds, including ratites, penguins, and diverse endemic island species.