The Serengeti wildebeest migration is an annual cycle of events involving three protected areas- Ngorongoro and Serengeti in Tanzania and the Maasai Mara in Kenya. The entire migration process is essentially controlled by the pattern of rainfall which in turn depends on the movement of the Intertropical Convergency Zone (ITCZ) zone belt.
As the first rains start arriving in the short grass plains of the Ngorongoro and Serengeti early in November, The Wildebeest populations accompanied by large herds of Zebra and some herds of other antelopes, start arriving these areas late in November or early December, These migrating wildlife species will stay in the short grass plains south and east of Seronera including the northern part of Ngorongoro Conservation Area through January, February and March during which time, the majority of females will give birth to young ones.
When the grassing condition of the short grass plains has deteriorated, these migrating wildebeests, zebras and other antelopes start moving westwards into the woodland zone of the Serengeti, where much of the grass is still green and abundant water supply. By May the bulk of wildebeest migrant is widespread in the western part of the Serengeti. From here, they then start moving northwards crossing the Grumeti River.
In July, the migration continues to move northwards, passing through the Grumeti and Ikorongo Game Reserves and by August the majority of wildebeests, Zebra and other migrating antelopes have already crossed the Mara River in the north heading for Maasai Mara in Kenya. In mid-August the migration is already in Maasai Mara where it stays until at the end of October, when it starts heading south towards Serengeti National Park and Ngorongoro Conservation area through western Loliondo Game Controlled area.
By the end of November, the migration is again back in the short grass plains of the Ngorongoro and Serengeti grazing on the green grass which follows the first rains on the short grass plains. Then the cycle begins again.