Gemsbok (Oryx gazella) male and female, also known as the African oryx. The bull (right) is checking on the cow (left) who is in oestrus and sexually receptive. This large antelope eats grass and leaves and can go without water for long periods. Both the male and the female have horns, which are effective weapons and used in defence. The gemsbok lives in savanna in parts of southern and eastern Africa. Photographed in the Northern Cape, South Africa, in the Kgalagadi Transfrontier Park.