Enzootic geophagy by elephants (Loxodonta Africana) in relation to geochemical composition of mineral licks in Addo Elephant National Park, South Africa

Abstract

Geophagy, the deliberate ingestion of soil, is a common occurrence amongst various animal species including mammalian herbivores such as elephants. Despite the documented instances of soil-eating, and several nonexclusive hypotheses, the real motivation behind the phenomenon remains controversial. In this study, six camera traps were set up throughout Addo Elephant National Park, South Africa at selected geophagy sites which captured visitation frequency as well as the demographic trend of elephant groups during site visits from April 2019 to May 2020. The geochemical and mineralogical composition of soils at these selected geophagy sites were analysed using X-ray diffractometry (XRD) and X-ray fluorescence spectrometry (XRF). Furthermore, the spatial distribution of five collared elephants (three matriarchs and two males) in relation to the six geophagy sites were investigated using kernel density estimations (KDE). Females had larger home ranges that incorporated more geophagy sites than males. Visitation frequency to geophagy sites were estimated using 500 m buffer zones from the centre of each site. Individuals visited at least three or more geophagy sites throughout the study period. Overall, essential elements Na, Ca and Mn were identified as main drivers for geophagic behaviour in the elephants of AENP. These essential elements (Na, Ca and Mn) are important for certain physiological demands such as bone and tusk growth in elephants and reproductive (pregnancy and lactation) demands in females. Geophagy is considered to be a contributing factor of movement patterns and area utilisation and may have important implications for conservation and management.