► THE GREATEST ANIMAL MIGRATION (HD, Full Documentary)

Month by month: the Serengeti wildebeest migration
The short rains begin around early November. A little after this, in late November and December, the herds of the wildebeest migration arrive on the short-grass plains of the Serengeti. These are south and east of Seronera, around Ndutu and include the north of the Ngorongoro Conservation Area. Dispersed across these plains, wildebeest and zebra are everywhere – feeding on the fresh, nutritious grasses. They stay here through January, February and March, with most wildebeest calves born in a short window around February. Gradually they spread west across these plains, then around April they start their great migration north.

By May the Serengeti's wildebeest all seem to be moving north, migrating to seek fresh grazing and water. The area around Moru Kopjes and west of Seronera is then hectic with a series of moving columns, often containing hundreds of thousands of animals – joined by many zebra, and a scattering of Thomson's and Grant's gazelles.

Some of the migration then head due north of Seronera, but most are usually further west. Around June the wildebeest migration is often halted on the south side of the Grumeti River, which has some channels which block or slow their migration north. The wildebeest then congregate there, in the Western Corridor, often building up to a high density before crossing the river. The river here is normally a series of pools and channels, but it's not continuous – and so whilst they always represent an annual feast for the Grumeti River's large crocodiles, these aren't usually quite as spectacular as the crossings of the Mara River, further north.

The wildebeest migration continues moving northwards during July and August, often spreading out across a broad front: some heading through Grumeti Reserve and Ikorongo, others north through the heart of the Serengeti National Park.

September sees the herds spread out across the northern Serengeti, where the Mara River provides the migration with its most serious obstacle. This river gushes through the northern Serengeti from Kenya's adjacent Maasai Mara Game Reserve. Watching the frantic herds of the wildebeest migration crossing the Mara River can be very spectacular; there are often scenes of great panic and confusion. It's common to see herds cross the Mara River north on one day, and then back south a few days later.

By October the wildebeest herds are migrating again with more accord: all are heading south, through western Loliondo and the Serengeti National Park's Lobo area, returning to the green shoots which follow the rains on the short-grass plains of the southern Serengeti in November.

Then the whole Serengeti Wildebeest migration starts again 

Millions of these gnus join forces annually to participate in one huge migration - always with luscious grass in their sights. Roaring, snorting, bucking, continuously reproductive en route, they head west - across the Serengeti from Tanzania to Kenya and back. With a large variety of animals in their wake - friend and foe: zebra families that resemble pale flotsam in a dark ocean amidst the gnu herds; or lions, and hyaenas in hope of their next victims. Along their way, they encounter hippopotami and crocodiles - and all of them embroiled in the cycle of "devour and be devoured". The filmmakers follow the artiodactyls, armed with their cameras and lay in wait on the so-called "birthing meadow". There, in the world's largest maternity room, 250.000 calves will be born within the next three weeks. The journey from there to the pasture regions of Kenya is especially dangerous for young animals - and here the film also illustrates nature's harshness. And then there is the "revenge of the gnus". The two filmmakers gained unusual access to the world's most famous game reserve whilst shooting their film in search of the even-toed animals.