It is that time of the year when Goa gears up to welcome all national and international tourists to the warm sands and sunshine of the state. Somewhere not seen by everyone another kind of preparation is underway by the birdwatchers of Goa, getting ready to welcome and document the winter visitors to the state. These winter-visiting birds undertake an arduous journey every year, which is termed as migration.
Migration is the regular seasonal movement, often north and south, undertaken by many species of birds. Bird movements include those made in response to changes in availability of food, weather, or habitat. It has been estimated that about 1,800 species of the birds in the world are long distance migrants. By long distance we really mean long distances, the longest spanning from the North Pole to South Pole undertaken by the Arctic Tern.
The most common pattern observed in bird migration involves, flying north during spring to breed in the temperate northern hemisphere and returning in the autumn to wintering grounds in warmer regions to the southern hemisphere. Many birds, from the strong and robustly built Greater-Spotted Eagle to the diminutive Booted Warbler are regular migrants to India. Goa every year hosts about 120 species of migratory birds in various habitat types, ranging from the coastal mudflats to the ridges of Western Ghats.
Goa witnesses three broad types of bird migrations- Local Migration, Passage Migration and Long distance Migration. Birds such as the very common Black Kite, the bright Indian Golden Oriole and the very beautiful Indian Paradise Flycatcher are all classified as local migrants to Goa because, during the monsoon season, these species move out of the state towards adjacent drier regions of the Indian Subcontinent and come back post monsoons.
Some species like the charismatic Amur Falcon and the European Roller are termed as Passage Migrants since they make a brief stop-over in Goa, before moving further south towards their wintering grounds. A majority of other species of birds like the Ruddy Shelduck and the Eurasian Marsh Harrier are migratory species who winter in the state till the beginning of monsoons.
The ability of birds to navigate during migration is yet to be understood fully, but it is suggested that they use visual cues from stars and sun along with being able to perceive the earth’s magnetic field which aids them in finding their way.
Off-late, human activities have started causing widespread problems to bird migration at a global scale. Hunting along migration routes threatens many bird species, for example populations of Siberian cranes that winter in India declined due to hunting along the route, particularly in Afghanistan and Central Asia.
Structures such as power lines, wind farms and offshore oil-rigs have also been known to affect migratory birds. Other migration hazards include pollution, storms, wildfires, and habitat destruction along migration routes and in wintering grounds.
Carambolim Lake was once known as a wintering destination for thousands of individuals of migrant ducks and waders but in the past few years has seen a steady decline in the number of birds visiting the lake, however things are not as bad as they seem because these birds have chosen alternative wintering areas in the Maina-Curtorim wetland complex where they can still be seen in good numbers.
The Arctic tern holds the long-distance migration record for birds, travelling between Arctic breeding grounds and the Antarctic each year (about 9, 0000 km round trip).
Bar-headed geese are the highest-flying migratory birds, regularly reaching altitudes of up to five and a half miles above sea level while flying over the Himalayas in India. But the bird with the record for the highest altitude ever is the Ruppell’s griffon vulture, which collided with a plane at 37,000 feet (that’s seven miles!) in 1975 and was unfortunately sucked into its jet engine.
The Bar-tailed Godwit can fly for nearly 7,000 miles without stopping, making it the bird with the longest recorded non-stop flight. During the eight-day journey, the bird doesn’t stop for food or rest.
This winter, join birdwatchers from Goa Bird Conservation Network to enjoy watching these national and international visitors, during the Network’s monthly Birdwalks, while we simultaneously bring to you notes on one migratory bird every Sunday in this column.
Image: A flock of migratory Painted Storks by Pronoy Baidya
