Environmental factors and prey availability determine wintering habitat use by shorebirds along the west coast of India.

Abstract

The spatial and temporal factors governing shorebird habitat use are crucial for managing coastal habitats and halting the decline of shorebird populations in the Central Asian Flyway. Therefore, we investigated how environmental variables and prey availability influenced shorebird distribution and abundance across habitats and seasons along the west coast of India between January 2015 and December 2016. Systematic sampling design was followed to collect data on shorebirds, sediment and hydrological properties (organic matter and physico-chemical properties), and prey availability across habitats over different seasons. Prey density and environmental variables such as salinity, organic matter, and sediment moisture content differed significantly across habitats and seasons. Prey density was influenced by salinity, with higher densities in mudflats (>1000 individuals per m2) during the winter season. Prey density decreased considerably in all coastal habitats during the departure (748.45 ± 320.93) and breeding seasons (537.55 ± 342.29). The fluctuations in prey density and salinity levels had a strong influence on distribution and abundance of shorebirds. These findings highlight the importance of mudflats as a foraging ground during the winter and freshwater inflow in maintaining salinity in estuarine habitats. Therefore, any alteration of river flow (e.g., construction of dams and check dams) or mudflats (e.g., mangrove plantations) would have a serious impact on the availability of prey organisms and the population of shorebirds that depend on them along the Central Asian Flyway.