Last updated 27 July 2026 · 13 min read
Nearly two million animals on a 1,000-kilometre loop that never ends. What the Great Migration actually is, why the river crossings happen, where the herds are each month — and how to plan a safari around a spectacle that follows rain, not calendars.
“You hear a crossing before you see it — thunder from a clear sky.”
2.What is the Great Migration, really?
A circle, not a journey
The Great Migration is the continuous, roughly clockwise movement of about 1.5 million wildebeest — joined by hundreds of thousands of zebra and gazelle — around the Serengeti–Masai Mara ecosystem. It has no start and no finish. The herds are simply following the rain, and behind the rain, the freshest grass.
Zebra lead with their appetite for long grass, wildebeest follow to graze the exposed shorter growth their own numbers then fertilise. It is less a trek than a slowly rotating engine of grass, rain and hooves — one of the last fully intact land migrations on Earth.
3.The migration year: what happens when
compare_arrows At a glance
| Event | Usual timing | Where | |
|---|---|---|---|
| Calving | Roughly half a million calves born in a few weeks | Late Jan – Mar | Southern Serengeti / Ndutu plains |
| The trek north | Columns kilometres long move north-west | Apr – Jun | Central & Western Serengeti |
| Grumeti crossings | First river tests, first crocodiles | May – Jul | Grumeti River, Tanzania |
| Mara crossings | The famous chaos at the water | Jul – Oct | Mara River, Kenya & northern Serengeti |
| The return south | Short rains pull the herds back | Nov – Dec | Eastern & Southern Serengeti |
4.Why the river crossings happen
Fear, grass and momentum
By July the herds stack up on the southern bank of the Mara River. The grass ahead — in the Mara Triangle and the reserve's northern plains — is worth the risk, but nobody wants to go first. Crocodiles wait in the deep channels; the banks are steep and crumbling. So the herds build, mill, approach, retreat — sometimes for days — until pressure from behind finally shoves the first animal in, and the plunge becomes an avalanche.
That's also why no guide on earth can promise you a crossing on a given day. What good guides do is read the build-up: herd sizes, the direction of grazing, which crossing points have been active. Then you wait, engine off, and let the migration decide.
5.Where the herds are, month by month
calendar_month Month by month
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
Peak season
Good time
Low season
- Jan: Southern Serengeti — calving begins
- Feb: Peak calving; predators in numbers (Tanzania side)
- Mar: Last of the calving plains
- Apr: Herds drift north-west in long columns
- May: Western corridor; Grumeti build-up
- Jun: Grumeti crossings; herds edge north
- Jul: First Mara River crossings — Kenya season opens
- Aug: Peak crossings in the Masai Mara
- Sep: Herds resident throughout the Mara
- Oct: Final crossings as herds turn south
- Nov: Short rains draw the migration back into Tanzania
- Dec: Southern plains green up; the circle closes
Levels shown are for viewing the migration from Kenya. The Mara's resident wildlife is outstanding in every month.
explore Our safari experts say
person
Book at least four nights for a crossings-focused safari. Two-night migration trips see herds almost always — but crossings reward the extra days of patience.
Niroskos guide team · Masai Mara driver-guides
7.Migration questions, answered
Can a crossing be guaranteed? expand_more
No — and be wary of anyone who implies otherwise. In August–September your odds over three to four days are very good, but the herds answer to rain and instinct, not itineraries.
Is the migration only worth seeing at a river? expand_more
Not at all. A hundred thousand animals grazing to the horizon, columns marching in single file, predators shadowing the edges — the crossings are the headline, not the whole show.
Kenya or Tanzania for the migration? expand_more
July to October, the Kenyan Mara offers the shortest drives to the action and superb camps. Outside those months the spectacle lives in Tanzania's Serengeti. Many travellers combine both.
How do I photograph a crossing? expand_more
Position early, stay on the high bank your guide chooses, and shoot wide first — the scale is the story. A 100–400mm zoom covers the chaos; keep shutter speeds above 1/1000s for the leaps.
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