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.