A preliminary assessment on the seasonal dynamics of avian assemblages and feeding guilds in an urban lake ecosystem: A case study from Rabindra Sarobar Lake, Kolkata, West Bengal, India

Abstract

This study explores seasonal variations in avian diversity and feeding guild distribution at a human-altered lake ecosystem, i.e., Rabindra Sarobar Lake in Kolkata, West Bengal. Using the Point Count Method. 56 bird species were recorded across two seasons: Pre-Winter (August-October 2018) and Winter (November 2018-January 2019). Species richness declined by 22% in winter, with significant seasonal variation (χ² = 4.82, p< 0.05). Common Crow densities increased significantly in winter, while House Crow showed a 50.2% decline. Insectivorous birds were the dominant feeding guild in both seasons, comprising 43.5% in pre-winter and 50% in winter, followed by frugivores and piscivores. A notable 62.5% decrease in frugivores during winter may be attributed to reduced fruit availability. The continued presence of insectivores and piscivores highlights the ecological value of urban habitats in supporting complex food webs. These findings highlight the importance of habitat heterogeneity and the preservation of green spaces in sustaining avian diversity in urban environments.