Every year, from January to March, the Ngorongoro area of Tanzania comes alive with 200,000 gazelles, 750,000 zebra, and 1.2 million wildebeest traveling together in a spectacle unlike any other on the planet: the Great Migration. The day to day movement of these migrating herds is unpredictable, as wildebeest have no natural leader and will often split up or even go in different directions - however, the general path for all these animals is the same, making their journey from Tanzania to Maasai Mara Reserve in lower Kenya. This is when the calving season begins, a time when there is plenty of rain ripened grass available - during February the wildebeest spend their time on the short grass plains of the south eastern part of the ecosystem, grazing and giving birth to approximately 500,000 calves within a 2 to 3-week period: a remarkably synchronised event.

As the rains end in May the animals start moving north west, into the areas around the Grumeti River, where they typically remain until late June. July sees the main migration of wildebeest, zebra and eland heading north, arriving on the Kenyan border late July / August for the remainder of the dry season (the Thomson's and Grant's Gazelles move only east/west). In early November with the start of the short rains the migration starts moving south again, to the short grass plains of the south east, usually arriving in December in plenty of time for calving in February. Some 250,000 wildebeest die during this amazing migration, a total of 500 miles. Death is usually from thirst, hunger, exhaustion, or predation.