Responses of bird functional communities to anthropogenic disturbances in the naturally fragmented Southern Mistbelt Forests in the Midlands of KwaZulu-Natal, South Africa

Abstract

Forest disturbance poses major threats to biodiversity and forest ecosystem processes. Understanding bird species’ responses to disturbed forests is important for species conservation and forest management. Here, we assessed the impact of selective logging history (∼150 years), livestock grazing, alien plant invasion and adjacent matrix-type surrounding forest patches on bird species richness and functional diversity in 14 Southern Mistbelt Forest patches in the Midlands of KwaZulu-Natal, South Africa. The bird communities were surveyed using fixed-radius point-counts. We quantified functional diversity using three functional indices functional richness, functional divergence, and functional evenness. None of the disturbance types assessed affected the richness of bird species. The size of the forest patch affected bird species. For functional diversity, FRic was significantly higher in disturbed forest patches for forest specialists, insectivores and cup or ball-nesting birds. Functional evenness for the forest-sensitive groups, like forest specialists and insectivores, was significantly lower in disturbed sites. The results of this study showed that responses of functional communities and forest specialist bird species varied depending on disturbance type and intensity. We recommend that future studies assessing forest disturbance impacts on bird species use taxonomic proxies with different functional diversity indices for forest bird species conservation and management.