The Greatest Show on Earth
Not surprisingly, this impressive phenomenon is determined by
the availability of grazing, which in turn is dependent upon
rainfall. Essentially the wildebeest are taking advantage of the
strongly seasonal conditions, spending the wet season on the
plains in the south-east, and the dry season in the woodlands of
the north-west. However, the sheer weight of their numbers also
plays an important role in shaping the environment to their
needs.
Members of the vast wildebeest herd give birth more or less
simultaneously, usually over a period of three weeks sometime
between January and March, when optimum grazing is available on
the short grass plains at the base of the Gol Mountains.
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.
The timing of the wildebeest calving is probably linked to the
timing of the rut at the end of the rains in May and June. The
wildebeest move off the plains at this time to a smaller area
which is necessary to synchronise the rut. Interestingly, the
rut itself appears to coincide with the full moon suggesting
that the mating peak is triggered by the lunar cycle.
Typically, the wildebeest head north-west from the short grass
plains to the Western Corridor of the Serengeti and its Grumeti
River. This watercourse is their first real obstacle and
gigantic crocodiles are waiting for the hesitant wildebeest to
stumble at the crossing. From Grumeti, the herds move north,
often spilling over into the Klein's Camp Concession, before
crossing the Kenyan border into the Masai Mara. Here again, they
must cross a river, this time the Mara with its flotillas of
hungry crocodiles. The mass of grunting wildebeest remain on the
productive Mara grasslands until October or November. Then, as
the storm clouds gather in the south, the vast herds return to
their breeding grounds which, by the time they arrive, are once
again green and lush and the cycle begins again.
