The Great Wildebeest Migration, Month by Month
The Great Migration is not a single event but a continuous, year-round movement of roughly 1.5 million blue wildebeest, accompanied by some 300,000 zebra and several hundred thousand Thomson's gazelle, around the 30,000 km² Serengeti-Mara ecosystem spanning northern Tanzania and southern Kenya. There is no start line and no finish line; the herds follow rainfall and the flush of new grass in a great clockwise loop. Understanding that loop — and accepting that it answers to weather, not calendars — is the single most useful thing a traveller can do before booking.
What drives the movement
The engine of the migration is grass. The short-grass plains of the southern Serengeti and the Ndutu area, fertilised by volcanic ash from the Ngorongoro highlands, produce mineral-rich forage during the rains. As those plains dry out, the herds push north and west toward the permanent water and taller grasses of the western corridor and the Maasai Mara. The whole cycle is a response to a rainfall gradient, which is why the timing shifts by weeks from one year to the next.
December to March: the southern plains
In the green months the herds spread across the southern Serengeti and the Ndutu region of the Ngorongoro Conservation Area. This is the calving season: in a roughly three-week window around February, some 400,000 calves are born. The concentration of vulnerable young draws lions, cheetah, and hyena, making it one of the most intense periods for predator action anywhere on Earth.
April to May: the long rains and the rut
As the long rains arrive, the herds begin moving northwest into the central and western Serengeti. Columns of wildebeest stretch for kilometres. The rut — the mating season — peaks now, with males bellowing and sparring across the plains. Travel can be muddy and some camps close, but the landscapes are green and uncrowded.
June to July: the Grumeti and the western corridor
By June the herds reach the western corridor, where the Grumeti River presents the first major water obstacle. The Grumeti's resident crocodiles — some among the largest in Africa — stage dramatic, if less famous, crossings here before the herds turn north.
July to October: the Mara River crossings
This is the period most travellers picture: thousands of wildebeest massing on the banks of the Mara River, hesitating, then plunging across crocodile-infested water. Crossings happen in both the northern Serengeti and Kenya's Maasai Mara, often repeatedly and unpredictably, as herds shuttle back and forth chasing grass. Patience at a crossing point is rewarded or it is not — there are no guarantees.
October to November: the return south
As the short rains green the southern plains again, the herds turn back south and east, completing the loop. November is a quieter shoulder month, with the herds dispersed across the central and eastern Serengeti before the cycle restarts on the calving grounds.
How to plan around it
Because timing varies, book a camp positioned for the season you are targeting rather than a fixed date. Mobile tented camps follow the herds and reposition through the year, offering the best odds of being in the right place. For river crossings, the northern Serengeti often offers similar drama to the Mara with fewer vehicles. And remember that the migration is only part of the picture — resident lion prides, leopards, and elephants are present whether or not the herds are.
Explore on the map
The Serengeti, the Maasai Mara, Ngorongoro, and the river systems that channel the herds are all plotted on the interactive map. Trace the clockwise loop, compare camp positions by season, and plan to be standing where the grass — and the herds — will be.