Mid-Winter Diversity of Waterbirds in West Bengal, India

Abstract

Waterbirds are excellent indicators of wetland health, and studies on their abundance and diversity are of use in conservation management of wetland habitats. Thirteen wetlands in West Bengal were surveyed for waterbirds during mid-winter of 2018–19. Three consecutive surveys through line transects were conducted in each of the wetlands. In all, 110 species of wetland-associated birds were recorded, these comprising 69 winter migrants and 41 resident species. Out of the 110 species, 18 species are threatened as per the IUCN Red List 2021-1. The Greater Adjutant Leptoptilos dubius, Pallas’s Fish-eagle Haliaeetus leucoryphus, and Great Knot Calidris tenuirostris are Endangered; Common Pochard Aythya ferina, Greater Scaup Aythya marila, Asian Woollyneck Ciconia episcopus, Lesser Adjutant Leptoptilos javanicus, and Greater Spotted Eagle Clanga clanga are Vulnerable and rest 10 species are Near Threatened. The highest species richness of waterbirds was recorded in Gajoldoba, followed by Purbasthali, Ahiran Beel, and Barasagardighi. The catchment areas of rivers and oxbow lakes showed greater species richness, probably due to greater heterogeneity of habitats. Wetlands with longer shoreline harboured a good number of waders. Species turnover rate was highest between Gajoldoba and Santragachi Jheel (0.59). Gajoldoba exhibited the highest species diversity, while in Santragachi an overwhelming dominance of Lesser Whistling-duck was recorded. This is the first comprehensive report on the diversity and abundance of wintering waterbirds in important wintering grounds along the length and breadth of West Bengal, located on the East Asian-Australasian and the Central Asian Flyways. The high Wilson-Schmida’s index (βT) values highlighted the large turnovers between sites due to contrasting species presence/absence data, which may be influenced by the differences in the physical habitat makeup.