What triggers the annual wildebeest migration in East Africa?

The great wildebeest migration is an annual circle of movement of over two million animals from Serengeti National Park in Tanzania to Masai Mara National Reserve in Kenya.

Over 1.6 million wildebeest will lead the way as the rains approach in the Serengeti in late October or November and this is accompanied by 400,000 Thomson’s gazelle, 300,000 Zebra, and 12,000 Eland. These are the main migratory and they cross the ranges of over a quarter of a million other resident herbivores and, of course, carnivores. The lions, hyenas, leopards, cheetahs, and lesser predators will always follow the migration and this will be observed as more numbers of predators are seen following the wildebeest migration at the beginning of the circle.

What triggers the mass movement of the ungulates from Tanzania’s Serengeti to Kenya’s Masai Mara National Park

There are at least two possible answers, according to behaviorist and ecologist Harvey Croze, co-author of The Great Migration. The wildebeest’s journey is dictated primarily by their response to the weather; they follow the rains and the growth of new grass. And, although there is no scientific proof that this is true, it seems that they, and other animals, react to lightning and thunderstorms in the distance. ‘It would be surprising if even the wildebeest could overlook such prominent portents of change,’ writes Croze.

But it is probably instinctive knowledge, etched into their DNA by hundreds of thousands of years of natural selection, that is the major reason why these ‘clowns of the plains’ know in which direction they must travel. Over the millennia, those wildebeest that went the ‘wrong way would have died (of thirst and starvation) long before they could reproduce, so the wildebeest that lived to produce future generations were the ones that went the ‘right way.