1.5 million wildebeest, walking a 1,000km circle
From the Serengeti's calving fields to the Masai Mara and back - the largest overland wildlife movement on the planet, playing out on an annual clock.
Not one event - a year-round clockwise circuit
Around 1.5 million wildebeest, joined by roughly 200,000 zebra and 500,000 gazelle, follow the rains in a continuous loop between Tanzania's Serengeti and Kenya's Masai Mara.
Zebra graze the taller grasses first; wildebeest follow on the shorter growth behind them - two species reading the same landscape differently, each clearing the way for the next.
Plan a migration safariMonth by month around the circuit
The herd settles on the southern Serengeti's short grasses, near Ngorongoro and Olduvai Gorge. Around 500,000 calves are born here, up to 8,000 a day at the peak.
Calves mature quickly and the herd moves northwest toward the central Serengeti, growing into long columns stretching for kilometres. Males battle for mating rights along the way, before the herd reaches the Grumeti River for its first tense crossing.
The herd pushes north toward Kenya, culminating in the Mara River crossing - the migration's most dramatic moment, with crocodiles waiting below and predators along both banks.
Short rains trigger a turn south, back across the Mara River, through the Serengeti's eastern reaches - rich cheetah territory - before the herd disperses across the south ahead of the next birthing season.
The migration's single most dramatic moment
Thousands of wildebeest and zebra gather nervously at the river's edge before committing to the crossing. Some make it across; others are swept away or taken by waiting crocodiles.
Around 250,000 wildebeest - roughly a sixth of the population - are lost each year to river crossings, predation, thirst and exhaustion. Difficult to watch, but part of an ecosystem where every carcass returns nutrients to the land.
Scale that's hard to picture until you're there
The Great Migration - your questions answered
When is the wildebeest migration in Kenya?
July to October, when the herds cross into the Masai Mara and the dramatic Mara River crossings take place. They begin returning to Tanzania from October onward.
Why do wildebeest migrate?
Mainly for food and water, following rainfall patterns to fresh grazing. Moving in vast herds also offers safety in numbers against predators.
How far does the migration travel?
Around 1,000km round trip between the Serengeti in Tanzania and the Masai Mara in Kenya, repeated annually in a roughly clockwise loop.
What other animals join the migration?
Around 200,000 zebra, 500,000 gazelle, 18,000 eland and topi antelope all travel alongside the wildebeest, each species grazing different grass lengths along the route.
How many wildebeest die during the migration?
Around 250,000 annually - roughly a sixth of the population - from river crossings, predation, thirst and exhaustion. It's a natural part of the cycle that also nourishes the surrounding ecosystem.
Should I see the migration in Kenya or Tanzania?
Depends on timing - July to October favours the Masai Mara in Kenya, while January to June favours the Serengeti in Tanzania. We can advise based on your travel dates.