Do human-modified landscapes influence composition and diversity of foraging guilds in mixed-species bird flocks in Wayanad, southern Western Ghats, India?

Abstract

Foraging guild composition of mixed-species flocks were studied and compared between old-growth forests and selected human-modified landscapes with different intensities of modifications. We compared diversity and composition of foraging guilds of mixed-species flock participants across old-growth forests, coffee, cardamom and tea plantations in a high altitude, fragmented landscape of Wayanad District, situated in southern Western Ghats. Birds recorded from a total of 124 mixed-species flocks in the study area were classified into 19 foraging guilds based on the criteria of major food preference, foraging substrate and foraging manoeuvre. Foraging guild richness was the highest in coffee plantation sites, and leaf-gleaning insectivores were the most common and species-rich guild across the four habitats. Flocks of tea plantations had lower foraging guild diversity than that of forests, and flocks of cardamom plantations had lower foraging guild diversity than that of coffee plantations. Non-metric multidimensional scaling analysis revealed moderate differences in foraging guild composition across forest and plantation flocks. The study suggests the importance of habitat structural complexity in supporting birds of many foraging guilds and highlights the necessity of biodiversity-friendly management practices that preserve native tree cover to ensure long term conservation of birds in fragile human-modified landscapes in the Western Ghats.