Chemical properties and occurrence on Kalahari sand of salt licks created by elephants

Chemical and physical data from analyses of soil samples of Kalahari Sand deposits in Wankie National Park, Rhodesia, show that salt licks created and used by elephant are characterized by high concentrations of water soluble sodium. Soils with concentrations of calcium, magnesium and potassium in, for instance, termite mounds are used as licks only in regions where soluble sodium is not present in quantity in the soil. Shallow steep-sided salt licks are dug out by elephants with their forefeet during the dry season. Elephant dung is deposited in large quantities on and near salt licks at that season. A brown colour is present in aqueous extracts of salt-lick soils and is likely to consist of sodium salts of humic derivatives of elephant faeces or urine. Rainwater gathering in salt licks in the wet season has an equivalent brown colour and a high sodium content. Similar soil regions rich in sodium but not used as licks have no brown colouration in the soil extract. This brown soluble humic derivative may enable the elephant to detect the salt lick by smell. Licks appear to be important in the social life of the elephant populations. The intensity of present usage of salt licks by elephants is leading to localized soil erosion which will eventually result in the filling in of many clay pans with coarser sands.