The Great Wildebeest Migration refers to the huge annual movement of vast numbers of wildebeest accompanied by large numbers of zebras and gazelles searching for food and water between Tanzania and Kenya.
Although the migrations occur in a cycle between Tanzania and Kenya, most of the movement takes place in Tanzania which covers Serengeti National Park, Ngorongoro Conservation Area, Loliondo Game Controlled Area, and Grumeti Reserve. In Kenya the migration stretches to the Maasai Mara Game Reserve, bordering Serengeti National Park in the north.
From late November to mid-March, the wildebeest and other animals are already in the southern Serengeti and Ndutu in the Ngorongoro Conservation Area, mainly moving between the transitional borders of the two reserves. It is calving season for wildebeest at this time of year. With lots of calves born in the area, a host of predators like lions, leopard, hyena and cheetahs are around as they take advantage of the easy prey.
Each year, nearly 2 million wildebeest, zebra and gazelle make a circular tour between the Serengeti in Tanzania and the Maasai Mara in Kenya in search of greener pastures. They make their annual trek north toward the Maasai Mara between July and October, but their exact movements and timing vary from year to year.
Hippos and Nile crocodiles lay in wait at many river crossings. In addition to predators that take advantage of the water, hundreds of wildebeest may drown if they choose a time or spot to cross where the water is too high or fast.
During a two- to three-week period in January and February, wildebeest cows give birth to some 300,000 to 400,000 calves. This provides a feast for predators like hyenas and lions. However, because the predators quickly become satiated and are unable to consume as much as they would if the wildebeest birthing were spread out over more time, they have less of an overall impact on newborn calf populations.
Newborn wildebeests, known for gaining coordination faster than other ungulates, get to their feet two to three minutes after birth and are able to run with the herd after just five minutes. Before long, they can even outrun a lion!
In March, when the short-grass plains of the southern Serengeti dry out, the wildebeest head west toward the Tanzania woodlands. There are two theories, or a combination of both, that likely explain how the wildebeest know where to go: they follow instinct (etched on their DNA after generations of survival and natural selection); or they respond to the weather, following the rains and the growth of new grass.
Though this massive seasonal movement is driven by the perpetual need for food, being constantly in motion helps wildebeest evade large numbers of predators, many who can’t follow herds very far because they are territorial and/or have young depending on them.