Friday, October 19. 2018What is migration?
Migration is a fascinating phenomenon that Nature repeats every year. It is the seasonal movement of some animals, from one place to another, year after year, usually across vast distances. Birds, fishes, mammals, insects and reptiles all migrate. Animals migrate for many reasons. It may be to find food, or to escape harsh weather. Some may travel thousands of miles in the spring, and then, thousands of miles back in the fall. Animals also migrate in search of better food supplies, or a safe place to give birth to their young. Such migrations happen on a regular basis. Irregular migrations are sometimes triggered by famine or over-population. The Arctic tern, the sea bird, travels from one end of the world to the other end every year! This is the longest migration undertaken by any bird. This bird flies in zigzagging routes between breeding grounds in the Arctic and Antarctica each year, a distance of around 70,900 kilometres. They will spend about four or five months in Antarctica, before heading back to the Arctic. Scientists have extensively studied the evolution of migration. But no single theory has been fully accepted. Picture credit: google
Friday, October 19. 2018Can 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
Friday, October 19. 2018Which birds fly the fastest?
The fastest known bird in level flight is the white throated spine tailed swift. It has been recorded as flying at speeds of over 170 kmph. Common eiders, or coastal ducks, can fly nearly 75 kmph. Dunlins (shorebirds) once caught up with, and passed a plane flying at 160 kmph! Swifts, as their name indicates, are among the fastest of all flying birds. Peregrine falcons can chase their prey in level flight at 60 kmph, but when stooping or diving to catch it, they reach much higher speeds. Other high-speed birds include buzzards, which can glide between 110 and 130 kilometres per hour. Swallows are believed to be able to reach 160 kilometres per hour when migrating, but normally, they do not fly faster than about 50 kilometres per hour. Picture credit: google
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