The use of camera traps and sign surveys to investigate a predator assemblage and its response to carcasses in a Grassland biome on Telperion Nature Reserve, Mpumalanga Province, South Africa

Abstract

The effects of carrion on animal communities and ecological processes are poorly understood. Carcasses are valuable but short-lived resources and understanding how vertebrate scavengers interact with them and conversely, how carcass availability shapes predator communities, is essential for a deeper grasp of this ecosystem service. Such understanding is particularly important in transformed landscapes in the absence of apex predators. My study examines how decomposing adult male blue wildebeest (Connochaetes taurinus) carcasses affect predator and scavenger communities in the biodiverse but threatened Bankenveld grasslands of Telperion Nature Reserve, Mpumalanga, South Africa. Sign and camera trap surveys were implemented to study predator responses to three experimental treatments - open carcasses, caged carcasses and no carcasses (controls) - with five replicates each. Predator species diversity was reduced at both open and caged carcasses compared to controls. Occupancy models showed actively decaying carcasses lowered detection probability for most mesopred ators, except for black-backed jackals (Lupullela mesomelas), whose detection increased. This suggests that many mesopredators who may be inclined to scavenge, exhibit a landscape of fear response proximate to carcasses, especially when jackal numbers are high. Carcass presence did not significantly affect jackal diel activity; however, jackals were significantly more active at open carcasses than caged carcasses or controls during periods when a low percentage of the lunar disc was visible. Their response (number of visits) to carcasses varied, influenced by proximity to dens, distance from human infrastructure and reserve boundaries, and local mammalian species richness. Furthermore, invertebrates attracted to the carcasses proved to be a valuable secondary resource that was heavily utilized by the jackals before they could access carrion. These findings demonstrate that the presence of carcasses significantly influenced the behaviour of predator assemblages within the surrounding landscape. Carcass ecology should therefore be carefully considered when managing and conserving predator assemblages, especially in small, protected areas and modified landscapes where predator assemblages are not intact.