The Enduring Mystery of Bird Migration

The lakes of Jahangirnagar University in Bangladesh, about 20 miles from the capital city of Dhaka, are a haven for migratory birds during winter. Over 60 species of birds arrive from the cold Himalayan regions, and from even as far away as Siberia, to spend the winter in the temperate, food-rich lakes, canals and wetlands of Bangladesh, before flying off to Sri Lanka, Indonesia and China. They include several species of ducks, lesser and greater whistling teals, cotton geese, pochards, darters, pintail ducks and herons.

In recent years, however, the number and species of birds migrating to Bangladesh has sharply declined. Ornithologists blame global warming for the decline. The snowy Himalayan regions are not as inhospitably cold as before. Even Siberia is experiencing milder and shorter winters. Add to that local over-fishing, poaching and pesticide-laden runoffs, and it is clear why the lakes of Jahangirnagar University are not as alive with the chirping and the whoosh of the ‘guest birds’ as it was only a few years ago.

Still, the sight of migratory birds, fewer though they may be, is stunning. One minute they are resting gracefully on sandbars, surrounded by bright water lilies, and suddenly, inexplicably, they take to the wings, flying in a synchronized, parabolic arc until they spiral onto the sandbars, each bird returning (so it would seem) to the same spot. Striking in their dimpled reflections, the ducks and their cousins look purposefully to the right or left, waiting perhaps for that mysterious signal, flowing in from somewhere, to lift off into the misty, morning air again.

Across the lake, amid marsh grass, walk the great blue herons, looking for prey, as if also in prayer, patience personified.

Bird migration is one of the enduring mysteries of nature. We may keep adding to our knowledge of how birds steer themselves by starlight and how their internal magnets interact with the earth’s magnetic field but after their long-distance flights are exactly mapped and the science of migration is understood to the last detail, the intangible wonder of it will continue to fascinate us for as long as we share this planet with our avian friends.