Waterbirds as Wetland Sentinels: Assessing Avian Diversity in Relation to Soil and Water Quality in the Kole Wetlands

Abstract

The Kole wetlands of Thrissur, Kerala, support resident and migratory waterbirds within a seasonally flooded agricultural landscape. This study examined associations between waterbird assemblages and soil and water conditions at five sites: Palakkal, Pullu, Pullazhi, Adat and Puzhakal. Field surveys conducted from August 2025 to March 2026 documented bird abundance, species richness, diversity and feeding-guild composition. Water and soil samples were analysed for selected physicochemical characteristics, and water and soil quality indices were assessed alongside canonical correspondence analysis (CCA). Water quality differed among sites, with Adat showing the most favourable index category and Pullazhi the least favourable. Soil quality was classified as good at Palakkal, medium at Pullu and poor at Pullazhi, Adat and Puzhakal. Pullazhi had elevated turbidity (19.8 NTU) and the lowest recorded dissolved oxygen concentration (2.4 mg/L), accompanied by large congregations of Glossy Ibis and Little Egret. Puzhakal had strongly acidic soil (pH 3.75) and relatively low organic matter (7.94%), alongside reduced avian community evenness. CCA indicated associations between piscivores and dissolved oxygen; insectivores and omnivores and soil moisture and organic matter; and carnivores and more acidic soil conditions. These findings suggest that waterbird assemblages reflect local gradients in soil and water quality. Integrated assessment of avian communities and physicochemical conditions may therefore inform site-specific wetland monitoring and management.