Associations between African elephant (Loxodonta africana) movements and water across an environmental gradient in Southern Africa

Abstract

African savanna elephants, Loxodonta africana, occur across most of Africa. Elephants are water-dependent species, and will travel to great lengths to visit desired water sources. Whether these water sources are supplemented water holes, natural bodies of water such as pans, lakes, dams, ponds, or they are perennial or seasonal rivers. Elephants treat water sources differently as the ecosystem and environment around these water bodies vary across the southern African landscape and their immediate biomes around these sources. Several factors influence how elephants interact with these water sources, such as the surrounding vegetation and ease of access (slope). In this dissertation, various factors that impact elephant movements were explored. However, the main objective is to understand how water influences elephant movements. The study includes telemetry data from six sites across southern Africa and across a landscape and rainfall gradient. These sites are: Kunene, Etosha, Chobe, Hwange, Kruger and Gonarezhou. In each area of the landscape gradient going from West to east, sites with supplemented water were compared to those with minimal or no supplemented water. Non-supplemented water indicates that elephants rely on perennial or seasonal rivers to access water. The basis of the movement analyses for the elephant telemetry data was using turning angles. Turning angles were classified as either high or low; 0° to 90° and 0° to -90° are classified as low, and 91° to 180° and -91° to -180° as high. We test and hypothesise that elephants will have high turning angles correlated with water sources. Water source GIS data layers are not readily or easily accessible online. This is particularly true for protected areas, such as national parks and data layers consisting of supplemented water holes. So, while we used water sources to understand elephant movements, we also used elephant movements to see if we could determine locations of “unmapped” water sources. Understanding how water influences elephant movements is crucial for conservation planning, both in protected areas and between protected areas.