With the approach of winter it is a common sight to see flocks of birds flying across. Where are they going? Where have they come from?

“I saw my first migratory bird for the season,” is a commonly heard sentence among serious bird watchers. The excitement is contagious, as the winter months draw near.

The world of bird migration is ancient and fascinating. And a peep into it is engrossing.

Bird migration can be broadly defined as a seasonal journey made by birds. They make this journey for various reasons, the primary one being climate, food availability and habitat. Birds use migratory flying corridors known as “flyzways”, that span many continents, mountain ranges, rivers and coastlines. Research into their migration shows that they avoid geographical barriers and very large stretches of water.

“How do they know where to go and when to go?” is an oft asked question among people as they sight the arrival or departure of the migratory birds. It has now been discovered that these routes may be genetically programmed into the birds or else it was learned and mastered over the years of flying.

It has been found that birds fly at different altitudes during their long journey. According to an expedition team in the Himalayas, skeletons of the pin-tail and Black-tailed Godwit and Bar-headed Geese have been found in the Himalayas. It is said that sea birds fly low over water and rise to a greater altitude when over land.

Ancient sightings

Bird sightings were made about 3,000 years ago by Greek poets Homer, Hesiod and Aristotle. Muththappulavar, a poet from Madurai, wrote about the migrating white storks known as — Valasai. The Bible too has references to bird migration.

“Does the hawk take flight by your wisdom and spread his wings toward the south?” (Job 39:26)

Resident migratory birds build nests and breed in India, whereas migratory birds come visiting in search of food.

With the approach of winter, day light wanes and birds find it difficult to feed. Food is important to have a healthy reproductive system. So, they fly to warmer climes, feed well and when they know that it is time to fly back home, they leave. This is the reason why migratory birds do not build nests and breed in their host country.

“Another special feature to be noticed during these months is the breeding plumage. When they are flying in, they are normally dressed in rather drab colours. During the breeding time, they are decked up in flamboyant colours,” says Mr. Thirunaranan, of Nature Trust, Chennai. He points out that Vedanthangal and Koondankulam in South India are hospitable places for the birds as regards to food and breeding. Vedanthangal especially has 22 lakes around it.

The Bar-tailed Godwit is known for the longest known non-stop migration of any species – it flies up to about 10,200 kms.

However, all is not well in the avian world. Climatic changes and global warming have played a heavy hand and there are cases of overstays. Another serious problem faced by migrating birds is that of poaching and hunting on their stop overs. For example, the population of the Siberian Cranes declined due to hunting when they broke journey in Afghanistan and Central Asia. According to reports, these birds were last spotted at the Keoladeo National Park in 2002.

Visitors of any species are a joy to have around. We, as hosts must make it our responsibility, that they are treated well before they leave, whether they be two-legged or feathered. Can you imagine a world without the varied colours of our migrant- feathered friends?

Water birds

The Point Calimere Wildlife and Bird Sanctuary in the Nagapattinam district, in South India, is a meeting place for migratory water birds in India. In October, these water birds arrive from the Rann of Kutch, Eastern Siberia, Northern Russia, Central Asia and parts of Europe for their feeding season and begin their return journey in January.

These water birds include threatened species such as Spot-billed Pelican, Nordmann's Greenshank, Spoonbill Sandpiper and Black-necked Stork. Near-threatened species include Black-headed Ibis, Asian Dowitcher, Lesser Flamingo, Spoonbill, Darter and Painted Stork

Researchers at The Bombay Natural History Society have captured, studied, ringed and released over 2,00,000 birds during the course of several ornithological studies.

Keywords: bird migration