In Tarangire 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. It's the greatest concentration of wildlife outside the Serengeti ecosystem - a smorgasbord for predators – and the one place in Tanzania where dry-country antelope such as the stately fringe-eared oryx and peculiar long-necked gerenuk are regularly observed.