White rhino require a reliable supply of water, both for drinking (every two to three days) and for the protective layer of mud that helps shield their hides from biting insects. In Kruger National Park, 85 per cent of the white rhino population occurs in the Southern Region, where rainfall is higher than average and water holes are evenly distributed. Their senses of smell and hearing are good, but their eyesight is poor and redbilled oxpeckers warn them of potential danger.