Investigating Present Status of Floodplain Wetlands as Habitat of Water Birds and its Determinants: An Experience from Lower Part of Deltaic West Bengal, India

The wetlands of the Ganges delta have rendered complimentary habitats to a diverse range of water birds. But human intervention accompanied with some natural factors has deteriorated the quality of these habitats. Present study aims to assess the status of avifaunal habitability of 21 floodplain wetlands, interspersed over the lower part of the Ganges delta by using Avifaunal Habitability Index (AHI). Seven widely used Ecological Indicators namely Avifauna Density, Total numbers of Avifauna, Simpson Index of Species Dominance, Shannon-Weiner Diversity Index, Species Richness, Simpsons Reciprocal Index, and Shannon Evenness Index have been used to compute AHI. The result unveils that wetlands like Purbasthali (11.58), Chariganga (5.51), Char Chakundi–I (4.81) have granted higher avifaunal habitability while wetlands like Sudhakarpur (-4.23), Akandanga (-3.5), and Raibali (-3.29) have revealed perceptible degenerated situation. Spatial variation of the habitability status is examined by Wetland Threat Index (WTI) and size of the wetlands. One way ANOVA-Tukey’s post hoc test exhibits that wetlands with less threat (WTI > 0.08) extends healthier habitats (p < 0.001; F = 5.79) and vice-versa. Subsequently, the study also reveals that larger wetlands (> 101 ha) have recorded greater AHI score than the small wetlands ((< 40 ha) at < 0.001 significance level (F = 13.40)). Therefore, this paper not only categorizes some floodplain wetlands based on AHI but also addresses spatial pattern and determinants of such habitability status over the Ganges delta. This study may attract the researchers and policy makers to assess the health of wetlands by using simple composite index in local to global level.