A Guide to the Great Migration

Although the exact timing of movement changes each year, the herds generally follow the same clockwise circuit across the 25,000-square-kilometre Serengeti-Mara ecosystem, dictated by annual patterns of rainfall. The wildebeest begin the year in Tanzania, on the short-grass plains of the southern Serengeti, before moving west and then north into the Maasai Mara. From October, at the height of the dry season and once the Mara’s rich Red Oat grasslands have been reduced to a brown stubble, they gradually march back south to their calving grounds in the Serengeti, where the cycle begins all over again.

July to October is understandably the most popular period of the migration for travellers, when the herds are concentrated in northern Tanzania and the Maasai Mara, and the drama of the river crossings is at its peak. Witnessing a crossing can be an exhilarating experience: a frenzied mass of bearded, lanky herbivores leaping into the turbid water of the Mara River, squirming past the jaws of lurking crocodiles and scrambling up the opposite bank (where Lions often wait to pick off any stragglers).

There’s a huge element of luck when it comes to viewing river crossings, though – it’s a matter of being in the right place at the right time. The most experienced guides will do all they can to anticipate the movements of the herds, but crossings are never guaranteed. Wildebeest can spend hours gathering and jostling for space on the riverbank, and moving tentatively towards the river’s edge, before losing their nerve and scattering across the plains. It’s remarkable how quickly they respond to the shifting rainfall, too, and the fresh growth that it stimulates. A large herd on the southern plains of the Maasai Mara can disappear overnight – lured back across the border into Tanzania by the occasional downpour in the Serengeti.

But the Great Migration offers so much more than its most marketed melee at the Mara River. The memorable moments are often far away from the crowds of tourists, following winding roads across vast plains and through lush valleys, and simply appreciating the noise and sheer scale of the wildlife around you. Each phase and location of this year-long phenomenon throughout the Serengeti-Mara ecosystem provides a unique safari experience. The timeline that follows serves as a rough guide to the migration’s movement, and although it’s a continuous, cyclical journey with no real beginning or end, the arrival of newborn wildebeest and zebras in the southern Serengeti is a logical starting point.

January to March

At the beginning of the year, after the short November-December rains, the wildebeest can be found anywhere from the central Serengeti to the Ngorongoro Conservation Area in the south-east of the ecosystem. The conditions here are ideal for the herds to raise their calves: the well-cropped open plains offer less cover for the predators tracking the herds, and the volcanic soils produce mineral-rich grasslands, formulating nutritious milk for the newborn wildebeest and zebras. The majority of the calves arrive around late January and February, when the herds occupy the lower slopes of the Ngorongoro Crater highlands.

The numbers involved are astonishing – around half a million wildebeest calves and zebra foals are born here each year within a two-to-three-week period. 80% of the female wildebeest give birth at this time, creating an abundance of prey for predators and enabling more calves to survive the crucial first few weeks. Like other herbivores, they only give birth to single, precocial young, capable of standing within minutes and keeping up with the rest of the herd.

This is a fantastic time to experience the migration for those interested in witnessing the calving and big cats on the hunt – away from the mid-year crowds of the Mara, but surrounded by wildlife on an equally staggering scale.

April to June

Once the southern plains have dried out after the long rainy season, the herds begin to roam west and north in search of fresher grass, gathering in the central Serengeti along with thousands of zebras and smaller groups of antelope. The migration really starts to pick up momentum now, and around May and June the majority congregate on the southern bank of the Grumeti River in the Serengeti’s Western Corridor. Although not as spectacular as the Mara River crossings, the herds still have to navigate the river’s pools and channels, and escape the grasp of the Nile Crocodiles. A significant number of wildebeest and zebras don’t head west at all, but follow a more central route north towards the Kenyan border via Seronera and the Loliondo area.

July to September

This is traditionally considered to be the best time of year to experience the Great Migration, when the herds graze in the Maasai Mara and make their perilous journeys back and forth across the Mara River. The first lines of animals usually begin to appear on the Mara’s southern plains in July, but this can vary depending on the timing of the long rains. In a dry year, the wildebeest can make it to the Mara River ­– the most reliable permanent water source in the ecosystem – in early July; in a wet year, they can arrive as late as mid-August.

Crossing the Mara River

The Mara River forms the boundary between the Mara Triangle in the west and the Maasai Mara National Reserve to the east. It cuts across the landscape from near the Oloololo Gate in the north, to just south of the Purungat Bridge, where it joins the seasonal Sand River. At the peak of the migration here, thousands of wildebeest and zebras can gather on the alluvial banks. In some areas, the banks have been worn down after decades of crossing, but in others they are almost vertical on both sides of the river.

Whether the herds cross in their hundreds or thousands, it is a captivating scene, and a dream for wildlife photographers. But it can be quite a shocking experience, too. On average, of the 1.5 million wildebeest that trek into the Mara from the Serengeti each year, 300,000 die. Most are killed at river crossings, which seems senseless as you watch them risk their lives to get from one perfectly fine-looking patch of grass to another. But wildebeest – alive and dead – influence the landscape in ways that aren’t obvious at first. The carcasses that float down the river nourish an entire ecosystem – river fish, microorganisms, birds and even hippos. Their bones take years to break down beneath the water’s surface, functioning as a slow-release fertiliser for plants. And the bodies of those killed by Lions and other predators provide nutrients for the land where they decompose.

Predators of the Maasai Mara

As well as the gauntlet of the river crossings, the migrating animals face the constant threat of the Mara’s Lions, Leopards, Cheetahs and Spotted Hyenas. The Maasai Mara has one of the highest known densities of Lions in Africa, and the Serengeti-Mara ecosystem is also a stronghold for East Africa’s Cheetahs. These high predator numbers are largely sustained by the populations of indigenous animals, such as African Buffalo, Topi, Common Eland and Impala, rather than the glut of migrants. But with such an abundance of prey in the Mara between July and September, you have a good chance of witnessing hunting behaviour, or observing the fascinating interactions between predators and scavengers after a kill.

Spotted Hyenas are often misunderstood as gluttonous scavengers; however, they are incredibly smart and socially complex creatures, and excellent hunters in their own right – stalking and killing up to 90% of their own food. Without the stealth and speed of other predators, they rely on their power of endurance, running at a steady lope for many kilometres and wearing down their prey. The resource-rich Serengeti-Mara ecosystem supports the largest Spotted Hyena population in the world, with huge clans of up to 90 individuals.

October to December

By October, at the end of the dry season and once they have run out of grazing in the Mara, the herds gradually trek back south into the Serengeti. This again depends on the timing of the rainfall; if it’s late, they can still be in the Mara quite late into October, and this can be a great time to view river crossings outside of the peak summer months. In November and December, the wildebeest are usually spread between the northern Serengeti and southern Serengeti plains. At the end of the year, they begin to gather in large numbers ready to calve, and the cycle of this remarkable natural phenomenon starts all over again.

Our tours are timed to enjoy different stages of the Great Migration. To experience the calving season on the short-grass plains of the southern Serengeti and Ngorongoro Conservation Area, join our 'Tanzania’s Great Migration' tour in February. Or, to witness the unfiltered drama of the Mara River crossings, consider our 'Kenya’s Maasai Mara Migration' tour in August. You can also get in touch with our Tailormade team for a bespoke, migration-focused safari to Kenya or Tanzania.

An 11-day safari to northern Tanzania's Ngorongoro Crater and Serengeti National Park, including five nights in the southern Serengeti timed to coincide with the annual migration of 1.2 million Blue Wildebeest.

• Visit the world famous Ngorongoro Crater
• Witness the Blue Wildebeest migration on the short-grass plains of the southern Serengeti
• Abundant birdlife
• Lion, Cheetah & Bat-eared Fox all likely
• Maasai Giraffe, Black Rhino, Elephant & Buffalo
• Explore Lake Manyara National Park

11 days | from £5,995 (inc flights)

An 8-day tour focusing on the migration of Blue Wildebeest and other herd animals into the Maasai Mara, as well as the accompanying predators and birdlife.

• Visit the world-famous Maasai Mara
• Abundant African mammals, including Blue Wildebeest
• Five nights at a comfortable camp in the Mara
• Lion, Leopard & Cheetah all possible
• Expertly guided by local Kenyan naturalists

8 days | from £6,495 (inc flights)