When is the great migration?

The migration depends on the weather. Triggered by the rain, the annual pilgrimage must search for water and grass to survive. From about December to May with some seasonal variations in time scale the migrating herds are on the short grass plains from Lake Ndutu past Naabi hill.
There they give birth and regain their strength. In May as the water becomes the limiting factor on the short grass plains hundreds of thousands of animals stretching over many kilometres heard Northwest, Simba and Moru become the favourite places to watch them. The migration swings Northeast heading into the neighbouring Masaai Mara Game Reserve in Kenya during September. Around October the march begins again heading southwards back to Tanzania crossing the Mara and Kirawira rivers in pursuit of the nutritious grass in the southern plains where they began their journey 12 months earlier. This phenomenon is sometimes called the Circular Migration.