Does Substrate Quality Influence Diversity and Habitat Use of Waterbirds? A Case Study from Wetlands in Southern India

Wetland acts as an important habitat that supports a massive diversity of organisms, especially waterbirds. We examined waterbird diversity and habitat use in relation to abiotic factors at Mavoor and Vazhakkad, two major wetlands in southwestern India. The study was carried out from 2015 December to 2016 November. A total of 50 species from Vazhakkad and 40 species from Mavoor wetlands were recorded; 12 species were exclusive to Vazhakkad and three to Mavoor. Among them, 16 species were winter visitors in Vazhakkad and nine in Mavoor. Highest diversity of waterbirds was observed in the agroecosystem of Vazhakkad. Physicochemical variables were recorded for the two wetlands, and their effect on waterbird richness, abundance and diversity were correlated. Multivariate analysis showed the variation in diversity between the two wetlands (MANOVA: Wilks' λ = 0.933, F = 3.69, P = 0.006) and habitat wetland interaction (MANOVA: Wilks' λ = 0.694, F = 10.25, P = 0.00). Nonlinear regression analyses were carried out between the evolution of the ecological index in the two wetlands separately. The present study could determine the effects of anthropogenic disturbances on wetland function from this study.