Taxonomic, functional, and avian community dynamics in selected Southern Mistbelt Forests of southern KwaZulu-Natal and the Eastern Cape, South Africa.

Abstract

Human population increase and landscape transformation result in the reduction of natural habitats, such as forests, causing changes in forest patch composition, habitat amount, patch size, isolation, shape, and edges. This is challenging specialist such as Orange Ground-thrush (Geokichla gurneyi) and Lemon Dove (Aplopelia larvata) species unable to survive in fragmented habitats and also influencing the composition and distribution of avian species assemblages. Therefore, the main aims of this multifaceted study were to (1) assess the habitat requirements of two forest specialised bird species, the Orange Ground-thrush (Geokichla gurneyi) and the Lemon Dove (Aplopelia larvata); (2) identify if avian assemblage diversity and species functional trait diversity show consist patterning across different landscapes in a forest ecosystem; (3) determine the influence of vegetation structures on the taxonomic and functional diversity of avian forest species, and (4) modelling how to connect forest patches of higher functional diversity. In 2018-2019, we conducted a series of camera-trap surveys of 21- day periods and fixed-radius point-count surveys at 420 sites across 94 forest patches of Southern Mistbelt Forest of southern KwaZulu-Natal and Eastern Cape, South Africa, during the breeding and non-breeding seasons in conjunction with surveys of microhabitat structural covariates. Firstly, we modelled the probability of occupancy and detection for the selected two species, which showed that forest specialist species prefer a highly diverse habitat structure. Secondly, we quantified functional diversity measures based on species’ trait per patch to measure the influence of habitat and landscape configuration on each measure. This resulted in functional diversity measures which were highly influenced by patch size, the distance between patches and diverse landscape and habitat. Thirdly, we conducted RLQ analyses to examine the association between avian functional traits and microhabitat structures present at each forest patch.We found there was a significant difference in vegetation structure and species richness between forest patches. Lastly, we ranked the functional diversity measures scores of avian communities present at each forest patch to identify core habitat patches responsible for the contribution of high functional diversity measures. Protection of natural forest habitat and diverse landscapes is important in preserving avian communities.