Trait information
Data on species traits were obtained from existing literature and field surveys (2014~2019; Sinha 2021). Elevational distribution patterns were identified from surveys in both breeding and wintering seasons (Sinha 2021). Morphometric measurements such as body size, average body mass, bill length, wing span, tail length and tarsus length, along with clutch size and diet were gleaned from available literature (Ali and Ripley 1968; Buckton and Ormerod 2008). Birds were classified as ‘obligate’ and ‘non-obligate’ based on their dependence on the river or riparian zone for all of their life cycle activities such as feeding, breeding and roosting.
Any functional traits that were strongly intercorrelated (r > 0.7) were dropped from subsequent analysis to reduce multi-colinearity, while traits that summarised foraging and breeding behaviour were then retained in assessments of trait-environment relationships.