This is simply not true. Mother nature offers no guarantees, to anyone ever. But don’t worry! You will definitely see examples of all the animals that comprise the: great migration” including, wildebeest, zebra and Thomson’s gazelle, they may not be necessarily be part of the Great Migration of the Serengeti (for example, at Ngorongoro Crater the herds are mostly non-migratory). Both the species and the numbersmay vary widely from one location to another and from one time of year to another.
Still, having said all that, it is true that on one of our safaris you may very likely to see some part of migration. You may not see that dramatic river crossing (few people ever do), but you will likely see varying sized groups of wildebeest, zebra and Thomson’s gazelle as they graze, play and gather on the plains.