The Serengeti ecosystem (which covers about 25,000 km² of which the Serengeti National Park is the heart) is the annual theater of the great migration: about 3,000,000 large mammals (mostly wildebeest and zebra, but also gazelles). Thomson and Grant and other large ungulates).
From one year to the next, the movements of this fantastic herd can be very different.
In the green season (January to April, when the rains make the southern plains of Serengeti and NCA green again), the migration takes place in the South (Ndutu / Olduvai region). In these green plains, migration is rarely immobile, thunderstorms synonymous with new grass and water, cause wildebeest in permanent movements (backwards, change of course etc.).
In May and June, when the soil dries quickly, wildebeests then form huge columns (sometimes up to 40 km long) and return to the "woodlands" of western and northern Serengeti.
In the dry season (July to October), migration finds refuge in the more wooded and more irrigated areas of the North (North and West Serengeti, Maasai Mara in Kenya).
The first rains of November attract again wildebeest to the plains. The descent to the South can take months as two weeks if November rains are abundant.