White rhinoceroses are among the largest rhinoceroses in the world. Their natural habitat is southern Africa. Due to the great demand for their horn, the animals are poached intensely and threatened with extinction. The International Union for Conservation of Nature (IUCN) therefore placed the southern white rhinoceros (Ceratotherium s. simum) on the red list of endangered animals. In zoos, southern white rhinoceroses are considered easy to keep. The reproductive success of captive animals has not been so good, however.