BIRDS OF PARADISE

Birds (class Aves) are feathered, winged two-legged, warm-blooded, egg-laying vertebrates. Birds are characterised by feathers, a beak with no teeth, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a lightweight but strong skeleton. Birds have more or less developed wings; the only know species without wings was the moa, which is generally considered to have become extinct in the 16^th century