Six thousand miles to the south, on the Serengeti plains of Africa, the wet season is over. Storm clouds are gathering, but they no longer bring rain to the Serengeti. As lightning sets light to the tinder-dry grass, they bring fire.

With no fresh grazing here, the herds of wildebeest are heading north west for the shores of Lake Victoria where the grass should be greener. Each year, wildebeest trek nearly two thousand miles, clockwise, in a great circular route, following the fresh grazing.

But their migration takes them through the territories of many prides of lion, all of whom have been eagerly waiting for the arrival of the herds.

These herds are huge -perhaps a million animals. However many wildebeest are taken by predators, it can't make an impact on such big numbers.

Not so far away but on a much smaller scale, another migration is beginning. 'Locust hoppers' -young locusts who have not yet developed wings -are also searching for fresh pasture.

Their migration is triggered when their numbers build up and all the food is gone. They have to keep moving to find enough for them all to eat.

But without wings, they can't travel as far or as fast as the wildebeest -yet.

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