Foraging guild structure and niche characteristics of waterbirds wintering in selected sub-Himalayan wetlands of India

Guild structure and niche characteristics are important indicators of quantitative niche partitioning of a community. In the present study the niche structure was analyzed to determine whether resource partitioning reflected coexistence or exclusion of different waterbird species in relevant guilds at sub-Himalayan terai-dooars wetlands. Trophic guild structure and niche organization in wintering waterbirds were studied to understand why some species were rare and some were abundant and what possibly determined the diversity and abundance of multi-species waterbird communities. Two trophic components of niche partitioning, namely foraging habitat and foraging techniques, were considered in the present study. Cluster analyses based on foraging habitats and foraging techniques (i.e., two dimensions) provided bi-dimensional foraging guilds. Waterbirds precisely formed five distinct guilds, namely, medium and shallow water generalists, stalking waders, pecking waders, mud picking wader and divers. Further, a much higher diversity of waterbirds was observed from shallow and medium water habitats than deep waters which could be the outcome of higher net available trophic energy. Potential competitive interactions within infra-guild members were possibly minimized by using varied feeding techniques. The present study pointed out that the specialist guild members showed comparatively higher intraguild niche overlap, whereas generalist guild members showed much lower niche overlap. Results indicated that waterbird communities were influenced mostly by trophic resources at a site and the birds' ability to exploit them. Waterbird guild structures and niche characteristics thus provide important ecological indicators of the ability of wetlands to support a range of species. Further, information on guild structures and niche characteristics are surely important for monitoring the biotic health of sub-Himalayan wetlands that would be important to work out effective wetland conservation strategies.