Factors affecting the occupancy of forest mammals in an urban-forest mosaic in EThekwini Municipality, Durban, South Africa

Abstract

Urbanisation is one of the most rapidly expanding forms of landscape modification by humans and leads to large-scale loss and fragmentation of native habitat. This can alter the structure, composition and function of remnant habitat. Therefore, understanding the influence of both landscape and patch characteristics is important for understanding factors affecting the distribution of organisms in urbanised landscapes. Consequently, the aim of this study was to establish the responses of forest dwelling mammals to landscape and habitat structure in an urban-forest mosaic in the EThekwini Municipality Area, Durban, South Africa. Using presence and absence data of mammals from camera traps, we modelled occupancy of species using the occupancy modelling framework. The occupancy by Philantomba monticola was positively influenced by forest cover (%), woody cover (%), leaf litter (%) and stem density of large trees and negatively influenced by road density. For Tragelaphus sylvaticus, Potamochoerus larvatus and Hystix africaeaustralis, occupancy was influenced positively by forest cover (%), woody cover (%) and foliage height diversity and negatively influenced by road density. For Genetta tigrina and Chlorocebus pygerythrus, occupancy was positively influenced by leaf litter (%), woody cover (%), forest cover (%) and road density and negatively influenced by distance to road. Thus, species showed varying responses to landscape and habitat structural variables. Genetta tigrina and C. pygerythrus appeared less vulnerable to the loss of forest habitat and degradation in habitat quality whereas T. sylvaticus, P. larvatus and H. africaeaustralis showed strong negative responses to such changes. The semi-arboreal habits of G. tigrina and C. pygerythrus may be an important factor facilitating their adaptability to urban environments as they can move unimpededly across the urban landscape in search of resources. The diversity of responses suggests that landscape management approaches that consider the habitat requirements of multiple species are more likely to be successful in this landscape. We suggest that conservation efforts directed primarily towards the protection and restoration of structurally intact forest habitats is the most prudent strategy for the conservation of mammalian diversity in this landscape.