Throughout each year, some 2.5 million wildebeest, zebra, and various species of antelope follow the rains in a clockwise direction. They move between the grasslands of Kenya’s Masai Mara National Reserve and the sprawling plains of Tanzania’s Serengeti National Park, plotting a course determined by the amount of fresh grass available.
Because the Serengeti is one of the world’s oldest ecosystems, it’s possible the Great Migration has been happening for millennia. The herds settle in the southern Serengeti between January and March to give birth and feed on the fertile plains before moving northwards.
The herds don’t all move together — groups split off, leave at different times or go to different areas within the Serengeti. Some might even stay behind if there’s enough grass to sustain them. It means you can go at almost any time of year and still see signs of migration.