Determinants of elephant spatial use, habitat selection and daily movement patterns in Hluhluwe-iMfolozi Park.

Abstract

The ecological role of large herbivores is increasingly recognized due to their ability to influence ecosystem functioning and their impacts on faunal and floral assemblages. Knowledge on the determinants of spatial utilization is crucial towards the successful management of these species according to objectives set for the conservation of biodiversity. While numerous studies have investigated the factors influencing the movements and habitat preferences of large northern hemisphere herbivores, few have focused on members of the African megaherbivore guild. In the context of fenced reserves, elephants have been implicated in the degradation of habitat resulting in negative impacts on biodiversity. Using a kernel analysis approach, I calculated home range size and utilization distributions for five separate herds from an elephant population in Hluhluwe-iMfolozi Park and examined possible determinants. I explored differences in utilization intensity between herds and seasons by comparing the rugosity of utilization distributions. I used a utilization distribution-weighted composition analysis to determine seasonal habitat preferences within the home range and examined the factors influencing daily movement characteristics within different habitats in different seasons. Substantial variation in home range size and location, utilization intensity, habitat preferences and movement responses was evident between herds. Spatial and temporal variation in resource distribution and intra-specific competition explained differences in home range size and utilization intensity. Larger herds underwent more fission-fusion events than small herds, possibly due to resource scarcity and greater competitive interactions. Elephants preferred greener habitats during the dry season and appeared to conform to optimal foraging principles. They utilized forest habitats more than others, selected larger patches with high densities of favoured food items and included greater proportions of common woody species in their diet. Large groups foraged close to rivers in the wet season and appeared to broaden foraging choices in the dry season by moving further away. Restricted displacements in the early morning and evening suggested crepuscular foraging activity while greater displacements at midday could not be explained by the need for water. This study highlights the importance of considering variation in animal movements and habitat utilization in overall conservation planning and when evaluating threats to sensitive habitats, particularly in fenced protected areas.