A flock of Southern or Common Ostriches (Struthio camelus) performing Geophagia, the practice of eating earth or soil-like substrates such as clay or chalk. Geophagia is practiced either to assist the bird in its digestion of unripe fruits and/or to protect it from the toxins contained in the food. It is also practiced to help with the intake of minerals like calcium and sodium. Photographed in the Kgalagadi transfrontier park in Southern Africa.