The three-month-long Asian Waterbird Census, which aims to count waterbirds and get a picture of the health of the wetlands, has started. It will continue through February.

Participants can register through the eBird website. They can also download the eBird mobile app after registration to upload a bird count when they actually visit the field.

“We are focusing on waterbirds found in the wetlands,” said Kanad Baidya, the state coordinator of the census.

The East Kolkata Wetlands, Alipore Zoo, Nalban, Subhas Sarobar, Rabindra Sarobar, Palta Waterworks, Santragachhi Jheel, Baruipur Wetlands and Rajarhat-Kharibari Wetlands are some of the places in and around the city where waterbirds are found.

“Although very large, the migrant birds do not stay for long at the East Kolkata Wetlands because of disturbances. It is also a site for fishing,” said Baidya, a member of the Birdwatchers’ Society.

Illegal constructions within the notified area of the wetlands are a concern.

Outside Calcutta, Kalyani Lake, the ash dykes of the Farakka thermal power project, Ballavpur Wildlife Sanctuary near Santiniketan, Durgapur Barrage, Kulik Wildlife Sanctuary in Raiganj, Gajoldoba in Jalpaiguri, Fulbari in Darjeeling and Rasikbill in Cooch Behar are some of the important wetlands.

According to Baidya, the common waterbirds found are the Lesser Whistling Duck, Gadwall, Northern Pintail, Eurasian Wigeon, Tufted Duck and Ferruginous Duck. The Lesser Whistling Duck is a local migrant. The others are trans-Himalayan migrants.

“About 2,000 Lesser Whistling Ducks have been spotted in the Baruipur Wetlands,” he said.

Baidya said a Knob-billed Duck was spotted in Baruipur last week. “A Knob-billed Duck is relatively rare in south Bengal, and it’s encouraging to see that they have been visiting Baruipur regularly since 2020,” he said.

The annual Asian Waterbird Census (AWC) is part of the global International Waterbird Census (IWC).

The website of Wetlands International South Asia, one of the coordinating organisations of the census in India, lists information about waterbirds and the health of wetlands among the objectives of the census.

Its website says, the census will “obtain information on an annual basis of waterbird populations at wetlands in the region during the non-breeding period of most species (January), as a basis for evaluation of sites and monitoring of populations”.

It will also help “monitor on an annual basis the status and condition of the wetlands”.

The organisers want participants to cover the wetlands that they have been monitoring in the previous years before adding new wetlands this year.

Ashwin Viswanathan, part of the team that manages Bird Count India, a co-organiser of the census in India, said that the three-month duration for the census is aimed at giving people enough time to take part in it.

“Many people may not be able to participate in the census if there is only a 15-day window. People could be out of town during that fortnight,” said Viswanathan.

Baidya said the three-month duration will also help them record the passing migrants.

Although focused on the birds in wetlands, coastal birds will be counted, too.

“A coastal birding camp will be organised at G-plot, an island in the Sundarbans, in February,” said Baidya.