No where in the world is there a movement of animals as immense as the wildebeest migration, over two million animals migrate from the Serengeti National Park in Tanzania to the greener pastures of the Maasai Mara National Reserve in Kenya during July through to October. The migration has to cross the Mara River where crocodiles will prey on them. This is one of the highlights as the animals try and cross the Mara River alive. In the Maasai Mara they will be hunted, stalked, and run down by the larger carnivores. The Maasai Mara also has one of the largest densities of lion in the world. The Migration is rarely ever the same in terms of precise timing and direction, as local conditions influence grass growth. This means that the wildebeest may move off the open plains earlier in some years and remain in the northern woodlands for longer in others.