The fierce sun sucks the moisture from the landscape, baking the earth a dusty red, the withered grass as brittle as straw. The Tarangire River has shrivelled to a shadow of its wet season self. But it is choked with wildlife. Thirsty nomads have wandered hundreds of parched kilometres knowing that here, always, there is water. Between August and October, the baobab-studded Tarangire National Park has one of the highest concentrations of wildlife of any Tanzanian park.