Can all birds fly?


            No, not all birds fly. The ostrich, the largest bird on Earth is the best example of a bird that cannot fly. The ostrich is found in the African savannah. Though it cannot fly, it can run very fast, at a speed up to 72 kilometres per hour. An ostrich may be as much as 2.5 metres tall and weigh about 135 kilogrammes. Ostriches produce the largest egg of any living bird. One egg may weigh about 1500 grammes and have the same volume as 25 hen eggs.



            Ostriches, penguins, cassowaries, rheas, emus and liwis are the most well-known flightless birds.



            The penguin, found in Antarctica, has wings modified into flippers to aid it in swimming.



            The cassowary is a large, flightless bird from Australia and New Guinea. It is the biggest bird in Australia, and the second biggest bird in the world, after ostrich. Cassowaries grow to be about 2 metres tall and weigh about 60 kilogrammes. The largest known cassowary was 83 kilogrammes. The cassowary’s life span is about 40 to 50 years.



            Cassowaries have powerful legs and a helmet like crest on the head. They protect themselves by kicking. Cassowaries can run at a speed of upto 50 kilometres per hour.



            Rheas are found only in South America. They are also called South America ostriches. These birds have a height of about 1.5 metres and weigh more than 25 kilogrammes. Rheas are brown in colour.



            Kiwis are small flightless birds. They are the size of a hen, and weigh from 1.5 to 4 kilogrammes. There are three types of kiwis – the common kiwi, spotted kiwi and the little gray kiwi. All are found in New Zealand.



            An important difference between flying and flightless birds is the fact that flightless birds have smaller wing bones. Another distinction is the absent (or greatly reduced, or flat) keel on the breastbone of flightless birds. Flying birds have a keel on their breastbone. The keel anchors the strong muscles that move a bird’s wings during flight. Flightless birds also have more feathers than flying birds. These feathers weigh more.



Picture credit: google



 


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