Migration and Bird Ringing
The "Migration and Bird Ringing" is about the greatest mysteries of bird life. Another word fro migration is "Travelling". It is possibel for us to calculate the time of arrival of migrating birds. Some birds move from one area to another. This is called "Local MOvement". It is caused by the difficulty in living conditions and the change or shortage in food supply.
In countries like India, birds spend their summer in the highher regions of mountains like the Himalayas and come down during the winter to the foot hills or the Indo-Gangetic plain.
Birds face many dangers while trabelling long distance over hill, forest and plain and over large stretches of water. They are often driven out of their courses by strong storms or they get drowned in the seas. At nights, they are also, sometimes misled by bright lights.
Birds never fly at their fastest when they are migrating. Their speed is usually from 48 to 64 km an hour at the height of 900 meters. Some fly by day and some both by day and night. But most of them travel after sunset.
Birds usually travel in flocks. Usually, the male birds go first followed by the female birds in a few days.
In the past, people had strange ideas about bird migration. They believed that birds bury themselves in the mud and sleep throughout winter. Later, people studied birds by ringing. Bird movements were also studied by creating artificial conditions and studying their effect on birds.
Ringing is done by capturing a bird and puuting on to its leg a light band of metal or plastic. The band bears a number, date, identification marks and an address to which the finder is requested to return the ring.
From ringing studies, it has been proved that the main migratory movement is generally North to South in autumn and vice versa in spring. Ringing has also proved that birds cover long distances. Ther is evidence that the Woodcock covers 2400 kms by travelling from the Himalayas to the Niligiris. The wild duck covers 3200 to 4800 kms by travelling from Central Asia to Siberia to India. Even the willow warbler, which is half the size of a sparrow, covers 3200 kms and reaches India, every winter.
Primarily, birds migrate to escape bitter cold and a restricted food supply in spite of heavy loss of life on the way.
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