Factors determine the population characteristics of migratory shorebirds and their prey species in the coastal saltpans

Naturally-occurring seasonal saltpans serve as a major foraging ground for migratory shorebirds. Nevertheless, little is known about the role of various environmental factors in determining the density, diversity and species richness of shorebirds and their prey in India. This study was designed to collect quantitative data for the first time on the role of season, salinity, water depth, and prey availability in influencing the density, diversity, and species richness of migratory shorebirds in the eastern coastal saltpans of Tamilnadu, India. Selected sites were classified as seasonal saltpans and hypersaline saltpans based on the concentration of salinity in water. Shorebirds were counted systematically from (August) 2012 to (May) 2015 using the total count method. The measurement of salinity level and water depths of each sighting was also collected. The density, diversity and species richness of shorebirds showed highest in the seasonal saltpans than the hypersaline saltpans. The monsoon season attracted more shorebird density, diversity species richness when compared to other seasons. Calidris alpine was only the migratory shorebird species recorded in both types of saltpans and across seasons. The micro and macro-invertebrate prey species showed the highest in the seasonal saltpans. The Chironomid larva showed the highest turnover than other species recorded in the studied saltpans. The multiple regression models showed that the year, season, salinity, and water depth influence the shorebird density, diversity, species richness, and prey species' density with a more significant percentage. The study results found that saltpans are also an ideal habitat for migratory shorebirds and their diverse prey species seasonally.