This is the first country-wide citizen science activity on this scale on natural history in India.
A quarter century of ornithological observations of wetland birds of Kerala come with a mixed bag of joy and despair for birders.
At a time when the wetlands of the State are facing multi-pronged threats, the population of a few bird species has been found soaring whereas some others have nose-dived in the population chart. Researchers focused their attention on the data generated from the four Ramsar sites of the State - Sasthamkotta Lake, Ashtamudi Lake, Vembanad Lake and Kole Wetlands - and also the other important wetland habitats to get a bird’s eye view of the population trends of wetland avian fauna.
The brightly coloured purple swamphen is one species that have thrived amidst widespread destruction of its habitats. Its population trend analysis demonstrated that the species has increased in Kerala during the last decade.
Ornithologists arrived at the conclusion after evaluating the bird data picked up from the Asian Water bird Census (AWC) held between 1987 and 2014. The annual census, coordinated by Wetlands International, also happens to be the first country-wide citizen science activity on natural history in India. An influx of Eurasian coot, which was an added to the list of Kerala birds during the late 1980s, has been reported in the State during winter season, noted P.O. Nameer of Kerala Agricultural University, the lead author of the population assessment paper.
The painted stork, earlier evaluated as a vagrant visitor to wetlands of Malabar and south Kerala has spread beyond the region they are generally found predicted ornithologists, after taking into account the reports of its sightings in other parts of the State.
The population of Asian Openbill, extremely rare during the 1970s, has remarkably increased since 2001, with at least four census reporting the presence of more than 3,000 birds. So is the case of Eurasian spoonbill as there have been several reports of sighting of large flocks from Kole Wetlands, Vembanad Lake and Kuttanad Wetlands. Same is the case with blackheaded Ibis.
Indian spotbilled duck, glossy ibis, oriental darter, Asian woollyneck and spotbilled pelican recorded increased presence whereas the population of the river terns and cormorants remained stable.
But the bird group of terns underwent a steady decline over the years. From the nearly 30,000-strong population in 1993-94, it had plummeted to just near 10,000 in the last decade. The loss of estuarine habitat like Purathur in Malappuram district and disturbances in other estuaries might have contributed to this decline. The decline was evident in the relatively stable sites such as Kole Wetlands, rued the ornithologists.
The population of whiskered tern, which form the major chunk of the population of the terns in the State, too has fallen significantly. Gulls too painted a gloomy picture as they were sighted in lesser number during the past few censuses. The BirdLife International has recorded that 11 water bird species of Kerala come under the IUCN Red list threatened categories with the black bellied tern being one of the ‘Endangered’ waterbird species in Kerala.
The only report of black bellied tern during AWC was from the Kole Wetlands. great knot, a ‘vulnerable,’ trans-continental migrant, has been reported from four sites whereas the Asian woolly neck stork (another vulnerable species), has been reported from 44 wetlands across the State.
Threats identified
Demographic pressure, industrial development, pollution, urbanisation, agriculture and aquaculture and water transport have been adding pressure on the wetlands of the State.
Reclamation of wetlands and the aquatic ecosystems, which are often considered as wastelands, is spelling trouble to several taxa. The stake nets used for fishing removes a wide array of non-target organisms, which are functionally important to the aquatic environment. Destructive fishing practise are also taking a toll on the bird population, it was reported.
Unregulated fishing, reclamation of wetlands, dumping of solid waste and domestic sewage too posed threats to the wetlands of Kerala, according to ornithologists
