View our video on the right for an animated depiction of the timing of the Wildebeest Migration or read on for a detailed description.
By July, as the plains of the southern and eastern Serengeti dry out, the herds start heading north and west where there is more grass and more dependable water. The perilous journey from Tanzania's Serengeti plains to the greener pastures of Kenya's Masai Mara has begun.
In a dry year, the first wildebeest could be on Kenya's border near the Mara River (the only decent permanent water in the ecosystem) by early July; in a wet year, mid-August. If conditions are very good with plenty of grass and water, the herds will be spread out all the way from Seronera in the central Serengeti to the Mara River.
The northward wildebeest migration splits into two broad groups, each taking a different route.
The main group follows the Mbalageti and Seronera Rivers from the southern Serengeti and into the western corridor, crossing the Grumeti River. This watercourse is the first real obstacle for the herds, not least because gigantic crocodiles are patiently waiting for the first wildebeest to stumble at the crossing. Remaining in the western Serengeti until July after which the land dries out completely, the wildebeest then head from the Grumeti region to the Masai Mara and its greener pastures. Here again they must cross a river: this time the Mara with its masses of hungry crocodiles.
This is one of the most exciting chapters in the annual migration - the drama of the river crossings makes riveting game viewing but you'll need to book your safari or accommodation far in advance to get front-row seats. And if you are lucky enough to witness a river crossing, you are sure to develop a new understanding and respect for the struggle for survival on the African savannah.
The second group heads directly north from the plains through the central Serengeti and directly into the northern Serengeti and Masai Mara without entering the western Serengeti.
In the Masai Mara, the rains have created a green and grassy landscape and up to 1.5 million animals pour in from the dry plains of the Serengeti. A safari in the Masai Mara National Reserve or its adjoining private conservancies between August and September after the wildebeest have arrived is an unforgettable experience. The sheer numbers are staggering as is the variety. Head out on a game drive and in a single glance you may be able to see ten or more species at a time - wildebeest, zebra, giraffe, buffalo, elephant, hyena, lion, eland and gazelle.
The mass of animals remain on the productive Mara grasslands until October or November. And then, as the storm clouds gather to the south, the vast herds return to their Serengeti breeding grounds which, by the time they arrive, are once again green and lush.
View all our Migration tours & safaris.
A Seasonal Guide