The International Waterbird Census is a monitoring programme operating in 143 countries to collect information on the numbers of waterbirds at wetland sites.
India is also a part of this monitoring programme under the Asian water bird census, held mid-winter every year.
It is a citizen-science program supporting conservation and management of wetlands and waterbirds worldwide.
The observations were recorded on the eBird app.
It shows the populations of some migratory waterbirds, especially duck species visiting the Alappuzha region of Kerala, are falling.
The duck species like Northern Shoveler, Common teal and Eurasian wigeon, sighted in the previous surveys, were totally missing this time around.