Saturday, April 14, 2012
Modern birds have no teeth and with their front legs turned into wings, their bills or beaks have to collect and process their food. The bill of each species is admirably suited to its diet. Many birds have lost the power of flight during their evolution. The ostrich the world’s largest living bird- grew too big to fly. However, its size and fast running in short burst give it plenty of protection. Rheas in South America, emus in Australia and cassowaries in New Guinea have evolved in similar ways and have all come to look alike, although they are not closely related. Birds living on islands with no mammalian predators often became flightless. The kiwi of New Zealand is a familiar example. Some of these birds died out when man introduced cats and other mammals, and many more are now in danger of extinction. Penguins cannot fly in the air, but they use their powerful wings as flippers to fly underwater.