The Great Wildebeest Migration is one of the last mass terrestrial wildlife movements left on the planet and the chief reason why so many safari-lovers venture to the Serengeti-Masai Mara ecosystem, especially at mid-year.The Migration is one of nature’s greatest paradoxes: your timing is absolutely everything but there is no way to predict the timing of the animals’ movement. We know that the wildebeest (and a smattering of zebra and antelope) will cross the Mara River – but we don’t know exactly when. We know that rain will trigger those same plains game to move onto fresh grazing – but we don’t know when that rain will come.