Grouping across taxa is a trade-off between benefits like shared foraging advantages and collective vigilance, and costs including competition for resources. Mixed-species groups (MSG hereafter) are a special class of associations, where two or more species associate with each other. Like other associations, MSGs also depend on cost-benefit ratios. These dynamic groups can differ structurally and functionally, and each functional state can represent different ecological roles or adaptive strategies. The structural organisation of these groups indicates a rule-based assembly. Similar species may group with each other for anti-predation benefits and to reduce the cost of activity matching; alternatively, functionally different species may associate more than expected by chance to avoid competition.
Heterospecific associations have been studied across multiple taxa; however, a majority of studies have been carried out on forest birds, and to a lesser extent on mammals and fish. Little is known about heterospecific grouping in a wetland context. Wetlands are unique, complex, and diverse ecosystems that can support various living organisms. These wetlands are widely different from forest ecosystems in habitat and community structure. Wetlands are open, have patchy resources, and support different life forms, including avifauna. Of the 1350 species of birds recorded in India, more than 300 are classified as waterbirds. Studying grouping dynamics in wetlands is also significant for conservation, as these groups play a vital role in maintaining the wetland ecosystem, both in nutrient cycling and food web regulation.
My study aims to understand patterns and drivers of heterospecific sociality in waterbirds across multiple Indian wetlands. First, I will explore the broad structural, functional, and compositional patterns of MSGs across wetlands and seasons. Then, I plan to examine trait-based group formation rules associated with functional groups and ecological context. In relation to that, I will analyse the dynamics of interactions to understand how centrality works in different functional and ecological contexts. Finally, I will investigate the influence of natural factors (e.g., the presence of avian predators) and anthropogenic disturbance on wetland MSGs, i.e., do species adapt their grouping strategy to cope with disturbance? The ultimate goal of this thesis is to provide a framework to infer how changes in group dynamics affect the broader ecological roles of waterbird MSGs.