The key to experiencing this iconic wildlife spectacle is to think of it not as a single event but a never-ending procession of animals through Tanzania and Kenya, says Andrew Purvis

From the high vantage point of our safari vehicle, paused on the parched golden plains of the Serengeti, we see the tsunami of wildebeest coming. Heads lowered as if in determined concentration, they surge across the grasslands in a snorting, steel-grey tide of two or three thousand animals with a single goal in mind: leaving southern Tanzania with their young and following the snaking Grumeti River to the lusher pastures and abundant water courses of Kenya’s Maasai Mara National Reserve.

Suddenly, as if by telepathy, the entire herd slows to a trot and we find ourselves surrounded by them. They stop, and in the stillness all we hear is the sound of these surprisingly vocal animals grunting, honking and bleating as camera shutters whirr.

Each April and May, more than 1.5 million wildebeest – plus half a million Burchell’s zebras, antelopes and other herd animals – set off on this epic journey, later to be stalked by lions and picked off by crocodiles as they cross the Mara River. In June, when Tanzania’s rainy season ends, the Great Migration begins in earnest and peaks between mid-July and September – the best time to witness a river crossing. By October, the rains are back in Tanzania and the herd begins its return journey.

What is the Great Migration?

Though it is sometimes referred to as annual event, the Great Migration is a fluid and continuous, year-long journey of wildebeest, zebras, antelope and other grazing animals through Tanzania and Kenya in search of food and water – a circuit of some 1,200 miles, and arguably the greatest wildlife-watching spectacle on earth.

“The smell of rain and the sound of thunder spur the migration forward but also sideways and even backwards,” says Abercrombie & Kent guide David Bromham, who has led hundreds of safaris for the company since 1995. Along the way, many migrating animals fall prey to predators including lions, cheetahs, crocodiles and hyenas. According to Bromham, around 250,000 wildebeest and 30,000 zebras perish, the majority of them young animals. “On many occasions, mother wildebeest will just start running and keep running, not knowing that their young can’t keep up.”

One misconception, he adds, is that wildebeest travel in a single “mega-herd” of a million or more. While significant numbers into the multi-thousands do clump together, more often there are smaller herds spread throughout a region or regions.

Another misunderstanding is that witnessing the Great Migration is all about the river crossings, those dramatic moments on the Mara River when hesitant herd animals forge through the water only to fall prey to crocodiles. Crossings are part of the migration, Bromham concedes, but they are just one aspect of a much more complex picture including mating rituals, calving and the shifting fortunes of the herd.

When is the best time to see the Great Migration?

Rain patterns dictate the plans and movements of the herds, but these are becoming less predictable as a result of climate change. The good news is that, whenever you choose to visit – and wherever you are based – there will be lots happening and plenty to see and photograph. Here is a broad seasonal guide to the migration.

Baby wildebeest and stalking lions in Serengeti National Park

At this time of year, the herds are mainly found in southern Tanzania. “Wildebeest tend to congregate in February, when they give birth to as many as 500,000 calves over a three-week period,” Bromham explains. Here, the volcanic soil is rich in potassium, calcium and phosphorus, producing especially nourishing grass – and therefore rich milk for calves. Crucially, the grasses of the Serengeti are also short. “Wildebeest prefer to calve here, without fear of the predators that typically lurk in taller grass.” Nevertheless, prides of lions test the vigilance of the grazing herds.

Low rainfall and high drama as the Great Migration gets under way

By April, Bromham says, the grass in southern Tanzania has largely gone and the rainy season is winding down. The herds begin their trek north across the central and western Serengeti, grazing hungrily as they go. Deprived of water, they follow the Grumeti River west – but by June the waters are low, leaving crocodile-infested pools as the only source in the area. “Come July,” says Bromham, “the herd can be found in the northern reaches of Tanzania, near the border with Kenya.” They are heading for the water-rich Maasai Mara, fed by Lake Victoria about 70 miles away.”

Dramatic river crossings in the Maasai Mara Game Reserve

In late summer, large herds arrive in the Maasai Mara and crossing of the Mara and Talek rivers reach their frenzied climax. “August is probably the best month to catch a crossing,” Bromham says, “but take a book and plenty of patience, as it is a waiting game.” Lying in wait for stragglers are feast-or-famine crocodiles which haven’t eaten for months and can survive on fish and the fat in their tails for a year or more.

More than a million beasts head south as the rains return to Tanzania

The herds begin to leave the Mara and turn south. Ever on the move for greener pastures, they begin their return to the Serengeti for the start of Tanzania’s rainy season. “By early October,” Bromham explains, “the Maasai Mara grasslands are pool-table flat” because of excessive grazing. “The million-beast march starts the winding journey south, consuming approximately 5,000 tons of grass each day.”

We can get you to the heart of the Great Migration with a range of Tailormade Journeys, private safaris, bespoke adventures and Small Group Journeys. Our A&K Sanctuary properties include Olonana Lodge in the Maasai Mara plus two in the Serengeti – Swala Camp and Ngorongoro Crater Camp. Also in the Serengeti, Kichakani Camp changes location twice a year to maximize your Great Migration experience.

For the ultimate eco-friendly option, A&K Exclusive Tented Camp can be set up anywhere – including the Maasai Mara – with anything from two to 12 low-impact tents just for your family or group. In addition to the properties above, A&K works with numerous partner camps and lodges in the Serengeti and the Maasai Mara. It can also create a bespoke Private Great Migration Safari with any combination of stays in both destinations.