The first birds arrived on October 20 and their numbers are expected to go up by the end of November (file pictures)

Bhubaneswar, Oct. 28: Birds have started arriving in Chilika, Asia’s largest brackish water lake, for their winter sojourn.

The first birds arrived on October 20, said forest officials, adding that the numbers will go up during November. Chilika attracts a large number of migratory birds from Europe and north Asia.

Bimal Acharya, divisional forest officer (DFO) of Chilika, said: “The birds have just started coming in and now, their number is around 20,000. By the end of November, they will arrive in lakhs and stay here till the end of March. The birds come here because of the extreme cold conditions during winter and they cannot find food on the surface of the Earth because it remains under ice till the end of winter.”

There was a fall in the number of migratory birds last year. In Nalabana, the core area of the bird sanctuary, the number was 7,91,738 last year. It was 9,04,622 the year before, said sources. Experts linked the fall in numbers to the effects of climate change. The species visiting the lake, spread over Khurda, Puri and Ganjam districts, include gadwals, pintails and northern shovellers. Beautiful flamingos are also seen here.

Ornithologist Gahar Abedin said: “Around 160 species of birds are seen at Chilika in a migratory season. However, the number changes every year. When there is less snowfall, if the birds find their food on the surface of the Earth, their numbers would be less. These things can be studied well after the end of November.”

Speaking on the process of migration, green activist Biswajit Mohanty said it remains a mystery and nothing conclusive has been proven on how all these birds manage to come to the same place so far away every year. Small birds arrive first and the larger ones, later. They also go back after March in the same order.

In the last decade, the largest congregation of migratory birds in Chilika was recorded in 2000-01 when the lake got 15,13,518 winged visitors, said sources. Experts on the ecology of Chilika lake hinted at some drastic changes in the dynamics of the water body and said this should be studied by a team of scientists to figure out the exact details.

Birds are not the only species being affected by the changes in Chilika. Sources said though the number of dolphins in the lake has registered a marginal increase, the growth in their population has not been commensurate with the efforts being made in this direction. This is because 34 dolphins have perished in Chilika during the past five years.

Even water bodies in Bhubaneswar have started noticing the winged guests. The Ekamrakanan lake under the Chandaka Dampara Sanctuary gets more than 10,000 birds in the migratory season. They also return to their native places after March.