Why do some mammals eat soil?

AThe habit of eating soil or clay is known as geophagia (or geophagy). Soil is an important part of many mammal diets, providing minerals such as calcium, sodium, iron and magnesium, and aiding digestion. In certain herbivores it helps to absorb toxins, acting as a buffer that can prevent stomach problems. Soil is also a source of bacteria that are vital to the healthy functioning of complex gut flora.

Geophagia is seen in many African species, including elephants, rhinos, antelopes and mongooses, while areas high in sodium (known as lick sites) are frequently visited by a host of creatures in need of this essential element.

Red deer often eat soil in areas where grazing may be poor.