by Anushree Bhattacharjee
Most good stories begin with a sunrise; a magnificent golden-red sunrise splashing the eastern sky and heralding in a new day of endless possibilities. This story, however, begins hours before the sun was to rise, when velvety darkness still enveloped the world.I had roused myself out of a very warm and comfy bed with the aid of my reliable alarm clock and oodles of will power, and by 4.30 A.M., was creeping out to the car park, where soon other shadowy forms began to manifest and together we began to load the car.
We soon approached the vast expanse of the wetland where we had been coming every winter to count migratory birds. A few moorhens, a few waders, and then as we turned a bend in the road, there was a huge flock of waterbirds silhouetted against the morning sky. As light from the rising sun began to bathe the landscape, the small silhouettes began to shine brightly. “Pochards!” I sighed softly. The much awaited winter migrants had finally arrived!
Winter migration of birds is the regular cyclic seasonal movement that several birds undertake from their breeding grounds, largely in the Palearctic region to their wintering grounds farther south. Winter migrants start arriving in India by the month of September and they have been recorded as late as April. So why do birds migrate? It is usually for abundant food supplies, milder climates and safer nesting areas. A major stimulus seems to be the changing ratio of daylight and darkness. The longer days of the summer months in their northern breeding ground provide these birds with more time to find food and feed their young.Have you noticed your local lakes and water bodies suddenly populated by several unknown birds during winter? Ever wonder how they found their way there? We know that birds use the sun and stars as compass to navigate themselves. The earth’s magnetic field also plays a role in how birds navigate.
Birds have tiny grains of iron-containing mineral called magnetite embedded in their head just above their nostrils. These may be helping them to navigate using the earth’s magnetic field to find the true north. Birds also navigate using visual and olfactory cues. They have been known to use key land features such as mountains, large water bodies, coastlines and even large buildings as visual cues!