The migration of nearly two million wildebeest and zebra across the plains of Tanzania's Serengeti and Kenya's Maasai Mara is one of the oldest and last great land migrations. In order to follow the rains, they must cross the Mara River and brave the great perils there...crocodiles, trampling, and drowning. Zebras and wildebeests make great travel partners as they feed on entirely different grasses. zebras eating the long grasses, while wildebeests follow to feast on the fresh shoots.