MIRZA, Feb 23 - Thousands of winged visitors have made the mighty Brahmaputra river and its tributaries as well as nearby waterbodies including Deepor beel, Chandubi, Darabeel etc., a paradise for tourists and picnickers.
A visit by this correspondent revealed that thousands of migratory birds have taken shelter in the Brahmaputra and its nearby waterbodies after completing a troublesome journey of several thousand kilometres from winter-hit regions of Europe, Antarctica, North America, Russia, Ladakh, Siberia etc., making Brahmaputra river and its tributaries, waterbodies, islets, forests, cultivation fields etc., a heaven for the tourists and other visitors.
Sources said that over 300 species of migratory birds fly into India, either in search of food or to escape severe winter in their native habitats. In the Indian subcontinent, the majority of migratory birds are winter migrants while some birds migrate to India during summer also.
Migratory water birds such as ruddy shelduck (Tadorna ferruginea), common shelduck (Tadorna tadorna), red crested pochard (Netta rufuna), grey leg goose (Anser anser), common pochard (Aythya ferina), barheaded goose (Anser indicus), pintail duck (Anas acuta), mallard duck (Anas platyrhynchos), spotbilled duck (Anas poecilorhyncha), common teal (Anas crecca), Indian spot-billed duck (Anas poecilorhyncha), shoveller (Anas clypeata), tufted poachrd (Aythya fuligula), green sandpiper (Tringa ochropus), Indian tern (Chlidonias hybrida), common tern (Sterna hirundo), large egret (Egreta alba), red breasted goose (Branta ruficollis), black-necked stork (Ephippiorhynchus asiaticus), great cormorant (Phalacrocorax carbo) etc., have taken shelter adding another dimension to the beauty of the Brahmaputra river.
There is a report of some of the endangered and threatened birds like baer�s pochard (Aythya baeri), marbled teal (Marmaronetta angustirostris), oriental darter (Anhinga melanogaster) etc., sheltering in the Brahmaputra river and awareness needs to be created by the environmental organisations for conservation of these rare birds.
Sources said that predator birds such as grey headed fish eagle (Ichthyophaga ichthyaetus), pallas�s fish eagle (Haliaeetus leucoryphus), hen harrier (Circus cyaneus), eastern imperial eagle, amur falcon (Falco amurensis), pallid harrier (Circus macrourus) etc., have also been seen hovering in the sky and roosting in the trees near the Brahmaputra river.
Sources said that the migratory water birds have been visiting Brahmaputra river and other reservoirs and terrestrial areas of South Kamrup and other areas of Assam and India during winter from Europe and other regions because there is little food in those nations where winter is severe. Temperatures also dip severely in the northern regions like Europe, Russia, Ladakh, USA, North America, Siberia and some Asian countries etc. Availability of food and warmer weather have led the migratory birds to countries like India, Pakistan, Africa etc.
Sources said that majority of the migratory birds generally breed in European or other colder regions and visit (during winter) warmer southern regions like India, Africa, Sri Lanka, Pakistan where they get enough food and more warmth to make them comfortable.
Sources, however, said that some of the migratory birds such as asian koel, black crowned night heron, eurasian golden oriole, comb duck, blue-cheeked bee eater, blue-tailed bee-eater, cuckoos, scops owl etc., visit Assam during summer too.
It has been reported that the size of population of migratory birds migrating to Brahmaputra river and other areas of Assam is reducing year after year. It has been reported that indiscriminate or uncontrolled fishing and agricultural activities in the Brahmaputra and its islets have been adversely affecting the migration of birds to Brahmaputra river. Generally, large flocks of migratory birds were seen taking shelter in the islets and the edges of Brahmaputra river seeking food in the past few years, but now-a-days the uncontrolled agricultural activities in the islets and uncontrolled fishing activities in Brahmaputra river have disturbed the natural habitat of the migratory birds.
Experts said that the swimming of the birds in rivers and reservoirs helps in penetration of sunlight deep into the water by breaking the unnecessary surface film grown on the surface of the water. The penetration of sunlight helps in growth of bottom fauna, including zoo plankton and plant plankton. The zoo plankton and plant planktons are the main food of fishes and thus birds help in the growth of fishes and thereby birds are beneficial to mankind. Awareness need to be created for conservation of the birds highlighting the beneficial aspects of the birds.
Sources said that migratory birds use several methods to navigate their way during migration. Many birds use celestial navigation and some of the birds even detect the positions of the sun, stars and moon and thereby navigate their ways to locate their destinations. Some birds can even detect the ultraviolet radiations emitted by the sun too, sources said, adding that some birds use topographical landmarks such as mountains, river valleys and forests to orient themselves on the migration route. Many birds, especially seabirds, identify their destinations by characteristic odours, sources said.
Sources said that many birds possess instinct or some kind of internal compass or biological clock that guide them to the route of migration and locate their destinations.
It is interesting to note here that some birds even possess echolocation and can be guided by echolocation technique.