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. Herds of up to 300 elephants scratch the dry river bed for underground streams, while migratory wildebeest, zebra, buffalo, impala, gazelle, hartebeest and eland crowd the shrinking lagoons.

During the rainy season, the seasonal visitors scatter over a 20,000 sq km (12,500 sq miles) range until they exhaust the green plains and the river calls once more. But Tarangire's mobs of elephant are easily encountered, wet or dry. The swamps, tinged green year round, are the focus for 550 bird varieties, the most breeding species in one habitat anywhere in the world. On drier ground you find the Kori bustard, the heaviest flying bird; the stocking-thighed ostrich, the world's largest bird; and small parties of ground hornbills blustering like turkeys.