The Wildebeest Migration is an annual, year-round, clockwise movement of over 1.5 million wildebeest, zebra, and gazelle traversing the Serengeti (Tanzania) and Masai Mara (Kenya) ecosystem in search of greener pastures. Driven by rain, the herds cross dangerous rivers (notably the Mara River) and face heavy predation, with peak viewing in the Masai Mara typically from July to October.