Factors affecting warthog (Phacochoerus africanus) occupancy with presence of aardvark (Orycteropus afer) as a keystone species

Abstract

This study investigated the dynamics of warthog (Phacochoerus africanus) occupancy across two diverse properties. Warthog are a common mammal species prevalent across diverse landscapes in Africa. The distribution of warthog has undergone notable shifts due to climate change and species reintroduction, with consequential impacts on farmlands through activities such as damage to fences, pipelines, and crops. Moreover, warthog are carriers of African swine fever, posing a threat to swine biosecurity. The primary objective of this research is to determine the variables influencing warthog occupancy, focusing on the presence of aardvark (Orycteropus afer) as a possible keystone due to its facilitative capabilities supporting burrowing species. The findings provide a foundation for future studies aiming to map potential warthog distribution based on influential covariates. My hypothesis considered a range of factors such as the presence of aardvark, the presence of predators, vegetation type, soil composition, distance to perennial water sources, proximity to roads, distance to the nearest 10 trees (tree cover at site level), and camera efficiency, was tested using occupancy modelling with camera trap data from Atherstone Private Game Reserve and Mountain Zebra National Park. My hypothesis is that multiple drivers/factors influence warthog occupancy. The results revealed that warthog occupancy is positively influenced by the presence of aardvark and camera efficiency, while it is negatively influenced by the presence of predators (lion, Panthera leo and leopard, Panthera pardus), increased distance to perennial water sources, and shorter average distance to the nearest ten trees (potentially linked to vegetation structure/type). These covariates also impacted the detection probability of warthog at both study sites, highlighting the complexity of the factors influencing their occupancy. The understanding gained from this study emphasises the significance of considering multiple variables to predict and manage warthog occupancy, particularly as climate change likely can shape their distribution. Therefore, my hypothesis is supported based on the covariates that significantly influence warthog occupancy. The findings underscore the importance of ongoing research, incorporating additional covariates, to refine our understanding of the multifaceted influences on species (warthog) occupancy to improve effective management and conservation.