The Great Wildebeest Migration is often called the greatest wildlife spectacle in the world. One million wildebeest, with several hundred thousand zebras mixed in, constantly move in search of fresh grazing capable of supporting so many mouths. In July and August their route reaches the Mara river, the border between Tanzania and Kenya and the boundary between the Serengeti and the Masai Mara reserve.
Waiting for them are the Nile crocodiles, measuring up to 16 feet in length and invisible in the muddy water. The wildebeest have to run the gauntlet, often crossing in large numbers in the hope that the flailing hooves will keep these predators at bay. The vast majority cross, but the younger animals and any that get swept downstream by the strong current are quickly picked off. Other animals injure themselves descending the steep river banks and are swept away and drowned, making an easy meal for the thousands of vultures and marabou storks that wait in the shallows for the carcasses to be washed up.
To say "Now on" is not completely accurate. The crossing is now on. The migration is always on, as the herd move in a huge loop that takes in the Ngorongoro highlands as well as the very south of the Serengeti. Witnessing the crossing can get very congested with many vehicles out watching this incredible event. Visit the herds in late January in the Ngorongoro Highlands and not only will you have great tracts of land to yourself, you will also be there to witness the calving season and the birth of thousands of young. You won't be alone however. You will be joined by the lions and leopards looking out for easy meals of tender young flesh!
Wherever you see the herds of the migration it is an incredible site and an incredible noise. Its well worth the visit to Tanzania or Kenya.