Response of tropical birds to habitat modifications in fragmented forest patches: A case from a tropical lowland rainforest in south-west Sri Lanka

Abstract

Disturbed forest fragments comprise a substantial proportion of tropical landscapes, and these habitats along with associated ecotones have become important to tropical biodiversity conservation in human-modified landscapes. This study evaluated how tropical avifaunal communities respond to moderate habitat disturbances, such as shifting cultivation, selective logging and restoration from exotic plant species, in the Yagirala Forest Reserve, a fragmented tropical lowland rainforest in south-west Sri Lanka. Thirty circular plots with a 25-m fixed-radius, located to cover four prominent habitat types (secondary forest, Pinus-dominated forest, abandoned paddy lands and home gardens), were studied from March to December 2014. The results suggest that despite being fragmented and disturbed by human actions, the Yagirala Forest Reserve and associated ecotone collectively provide an important refuge for avifauna in the landscape context. The forest-home garden interface supported the highest avifaunal diversity. Edge habitats represented by home gardens and abandoned paddy lands generally supported greater bird richness. However, less disturbed secondary forest and Pinus-dominated forest were be more important for endemic and forest-specialist birds. Our results further highlight the potential value of wooded forest-home garden interfaces and forest stands restored with exotic pines in supporting native forest bird assemblages, especially in fragmented and isolated forest patches.