The Wildebeest Migration in East Africa, also known as “The Great Migration” takes place between Kenya's Masai Mara and Tanzania's Serengeti National Park and is one of the greatest wildlife spectacles on the planet.

Thousands of wildebeest and zebra’s migrate between the Serengeti and the Masai Mara, constantly driven by their search for fresh grazing. The massive herds are closely followed by predators (lion, hyena and cheetah), making the most of every opportunity to catch their next meal.
 

The precise timing of the annual wildebeest migration depends on the rains. It is a very unpredictable and spontaneous natural event, with calving season taking place in the Serengeti between January and mid-March. The wildebeest migration starts to head towards the Western Serengeti in May or June. The best time to see the migration is generally between June and August when the wildebeest congregate and prepare to cross the famous Grumeti River. If you are in the Masai Mara you can expect the wildebeest to make their arrival as early as July, but they generally arrive between August & September and remain in the Masai Mara between October & November. Between the end of November and January the wildebeest gradually begin their migration from the Masai Mara back towards the Serengeti.