The focus of the present study was (i) to develop a complete checklist, (ii) to find the seasonal variation of waterbird diversity, and (iii) to assess the population trends of different waterbirds at Lake-2 of the Ballavpur Wildlife Sanctuary (BWLS), Birbhum District, West Bengal, India. The study was carried out from January 2018 to November 2019. All waterbirds spanning in the freshwater lake were counted with field binoculars and digital cameras. The bird count data were used to calculate different biodiversity indices (such as Shannon-Weiner diversity index, Simpson’s Diversity Index etc.). Further, we assessed the population trends of different waterbirds with the data available from eBird. A total of 32 waterbird species belonging to 27 genera, 9 families and 8 orders were recorded during the present study. Dendrocygna javanica (Horsfield) was found to be the most dominant species throughout the year. Maximum richness and abundance were recorded during the winter months (December to February), whereas the highest species diversity was recorded during the monsoon months (March to June). The present study further establishes that both the richness and abundance of the waterbirds at BWLS have increased as compared to the past data. However, various species of wading waterbirds that were recorded previously were not observed during the present study. Moreover, the population trend analysis revealed a strong decline in the population of Mareca strepera (Linnaeus) and a moderate increase in the population of Ardeola grayii (Sykes). Thus, the present study concludes that BWLS supports high waterbird diversity irrespective of its small area.
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