The movements of these latter animals coincide with a pattern of rainfall in the Serengeti-Mara ecosystem; and their annual, roughly circular migration in the wake of the rains reveals a marvelous and intricate network of benefits to all the organisms involved—grazers, grasses, and predators. The timing of these events—the heading of grasses in seed, the dropping of manure, the arrival of the rains, the birth of the young—seems perfectly fortuitous, a melding of needs and satisfactions that caused those who first examined the events to speak of a divine plan.
