Joseph P. Dudley

Geophagy in the African Elephant in Relation to Availability of Dietary Sodium

Abstract We studied the use of mineral licks by African elephants (Loxodonta africana) during the dry season in a Kalahari-sand habitat in Hwange National Park, Zimbabwe, to investigate the role of geophagy as a mechanism for supplementing low Na+ levels in browse and natural water supplies. Plant, water, and soil macrominerals were measured to evaluate mineral availability for elephants during the dry season. Elephant behavior was monitored at licks to investigate the intensity of geophagy (measured by number of mouthfuls of soil consumed) in relation to fecal-Na+ loss. Female elephants, which probably had greater requirements than did males because of pregnancy and lactation, consumed more mouthfuls of soil and spent a greater part of their activity budget feeding on soil than did males, suggesting that geophagy may be driven by a nutritional requirement. We found the following consistent with the Na+-supplementation hypothesis: 1) unlike other minerals, Na+ in woody plants and natural water supplies may be inadequate to meet the minimum requirements of elephants during the dry season; 2) soils consumed by elephants differed from other soils primarily in their high Na+ content; 3) intensity of geophagy was negatively correlated with fecal Na+; and 4) elephants in non–Kalahari-sand habitats do not appear to create or use licks, probably because they are able to meet their Na+ requirements from ubiquitous Na+-rich water supplies, which do not occur naturally in Kalahari-sand habitats.