MASAI MARA WILDEBEEST MIGRATION:
The Wildebeest Migration in East Africa takes place between Kenya's Masai
Mara and Tanzania's Serengeti National Park and is one of the greatest
wildlife spectacles on the planet, where you spot millions of wildebeest
and hundreds of thousands of zebra, eland and gazelle grazing, crossing
rivers, arriving and leaving, is quite simply mind-blowing. The migration
is said to have been in existence hundred of thousands of years ago and
the cycle plays out year after year.
Timing of the annual wildebeest migration depends on the rains. It is a
very unpredictable and spontaneous natural event, with calving season
taking place in the Serengeti between January and mid-March. The
wildebeest migration starts to head towards the Western Serengeti for the
northern Serengeti plains and woodlands in May or June.The best time to
see the migration is generally between July and August when the wildebeest
congregate and prepare to cross the famous Grumeti River in Serengeti
for, Masai Mara we expect the wildebeest to make their arrival as early
as July, but they generally arrive between August & September and remain
in the Masai Mara between October & November. Between the end of November
and January the wildebeest gradually begin their migration from the Masai
Mara back towards the Serengeti.
Masai Mara reserve is about a third of the size of the Serengeti National
Park which also makes it a more manageable area for game viewing and its
also one of Africa's best wildlife destinations year round. Masai Mara is
a large game reserve in south-western Kenya, which is effectively the
northern continuation of the Serengeti National Park game reserve in
Tanzania.
About The Migration
The
stage on which this show is set is loosely termed
the Serengeti Ecosystem, about 40, 000 square
kilometres pretty much defined by the dominant
migration routes of the white bearded wildebeest (Connochaetes
tuarinus mearnsi) and comprises parts of the
Ngorongoro Conservation Area in the south; the
Serengeti National Park and the adjacent Maswa Game
Reserve and other ‘controlled’ areas in the centre,
east and west; and the Maasai Mara National Reserve
to the north. The principle players are the
wildebeest, whose numbers appear to have settled at
just under 1.7 million, with supporting roles from
some 400,000 Thomson’s gazelle, 300,000 zebra and
12,000 eland. These are the main migrators and they
cross the ranges of over a quarter of a million
other resident herbivores and, of course,
carnivores. The lions, hyenas, leopards, cheetahs
and lesser predators await the annual coming of the
migration with eager anticipation.
In
reality there is no such single entity as ‘the
migration’. The wildebeest are the migration – there
is neither start nor finish to their endless search
for food and water, as they circle the Serengeti-
Mara ecosystem in a relentless sequence of life and
death. ‘The only beginning is the moment of birth,’
notes acclaimed East African author and photographer
Jonathan Scott, who has spent the better part of the
last 30 years chronicling the events of the
Serengeti and Maasai Mara. Similarly the only ending
is death.
There is little predictability about the migration,
and questions as to which is the best month to view
it are likely to get different answers from
different people. According to Scott, ‘You could
spend a lifetime in the Serengeti-Mara waiting for
the typical migration. The finer details of the
herds’ movements are always different. It is a
dynamic process which defies predictions: no two
years are ever quite the same.’
Probably the most important element of the
environment to its inhabitants is the weather and
the cycle of four seasons per year undoubtedly has
the defining influence on the migration. The seasons
are reasonably defined: the ‘short dry season’ is
typically December to February/March; the ‘long
rains’ fall over a six week period from March
through April and into May; and the ‘long dry
season’ is from June to September, with the two-week
‘short rains’ falling any time from October into
November. There are however, no guarantees about
these dates.
The
Birthing
For
want of a better place in which to ‘start’ the
migration, we’ll begin in January and February, when
the wildebeest cows drop their young in a
synchronized birthing that sees some 300,000 to
400,000 calves born within two to three weeks of one
another, eight and a half months after the rut. The
birthing occurs on the short-grass plains that, at
the southernmost extent of the wildebeests’ range,
spread over the lower northern slopes of the
Ngorongoro Crater highlands and are scattered around
Olduvai Gorge. Here, at the ‘cradle of mankind’ many
notable fossil finds have been discovered, including
some that show that wildebeest have grazed the
Serengeti almost unchanged for over a million years.
The
annual period of birthing provides a feast for
predators. Driving across the plains, one can count
literally hundreds of hyenas and dozens of lions
scattered about. It may seem that the wildebeest are
doing the predators a favour by dropping their young
all a the same time, but in fact a surfeit of
wildebeest veal in a very short period results in
the predators’ becoming satiated and unable to
consume as much as they would if the calving
happened over a longer time span. The predators thus
have only a limited impact on the population of
newborn calves; any calves born outside the peak are
far more likely to perish.
To
watch any birth is amazing but watching the
wildebeest birthing verges on the incredible. A
newborn wildebeest gains co-ordination faster than
any other ungulates and is usually on its feet two
to three minutes after birth. It can run with the
herd at the age of five minutes and is able to
outrun a lioness soon thereafter. Notwithstanding
this, many do die within their first year, from
predation (although research indicates only about
one percent die this way), malnutrition, fatigue or
disease. Many calves get separated from their
mothers when the herds panic (which happens
frequently) or cross rivers or lakes in their path.
The calves then wander for days looking for mum,
bleating and bawling incessantly. On rare occasions
they may be lucky to find her, but no wildebeest cow
will adopt a strange calf, even if she has lost her
own and is lactating at the time. As it weakens, a
lost calf becomes an easy victim for any watching
predator, from jackal up to hyena and lion.
The
Start Of The Circle
Towards the end of the short dry season, around
March, the short-grass plains of the southernmost
Serengeti begin to dry out and the wildebeest begin
(or continue) their journey, heading towards the
western woodlands. How do they know which way to go?
There are at least two possible answers, according
to behaviourist and ecologist Harvey Croze,
co-author of The Great Migration. The wildebeests
journey is dictated primarily by their response to
the weather; they follow the rains and the growth of
new grass. And, although there is no scientific
proof that this is true, it seems that they, and
other animals, react to lightening and thunderstorms
in the distance. ‘It would be surprising if even the
wildebeest could overlook such prominent portents of
change,’ writes Croze.
But
it is probably instinctive knowledge, etched into
their DNA by hundreds of
thousands of years of natural selection, that is the
major reason why these ‘clowns of the plains’ know
in which direction they must travel. Over the
millennia, those wildebeest that went the ‘wrong’
way would have died (of thirst and starvation) long
before they could reproduce, so the wildebeest that
lived to produce the future generations were the
ones that went the ‘right’ way.
From
the plains around Olduvai the herds head west
towards the trio of small lakes, Ndutu, Masek and
Lagarja. At this time their biggest need is usually
to find water, and these more westerly areas can
provide it. Still feeding and fattening on the
nutritious short grass the herds scatter widely
across the plains, shifting on a whim in response to
factors beyond our knowledge. On any given day
they’ll be spread out in their tens and hundreds of
thousands across the expansive plains west of Ndutu,
the next they’ll be gone. By now the first downpours
of the long rains will be falling, and the
wildebeest will canter across the plains towards the
distant thunderstorms, frequently returning a day or
two later if the promise did not match the reality.
The
Rut
As
the rains set in, the herds head north-west past the
granite outcrops of the Simba and Moru koppies and
into the woodlands of the hilly country west of
Seronera towards Lake Victoria. This is the time of
the annual rut, with half a million cows mated in
less than a month as the herds consolidate in the
woodlands and on the plains of the Serengeti’s
Western Corridor. The peak of the rut seems heavily
influences by the state of the moon, with the full
moon in May/June being a good bet for anyone seeking
the most action.
Seemingly vicious fighting between dominant or
territorial males takes place during the rut, though
there is generally little actual violence or serious
injury. And in spite of these energetic duels, the
males have little say over their choice of mates,
for it is the females who do the actual choosing.
The
Crossing
From
the western Serengeti the herds head north,
following the rains (or their effects) into Kenya
and the Maasai Mara Game Reserve. On their trek the
wildebeests’ path is cut several times by rivers: in
the Serengeti by the Mbalangeti and the Grumeti, and
in Kenya by the Mara. For most of the year these
rivers are relatively placid, but they can become
violent torrents in response to rainfall in their
catchments areas, and then they present major
obstacles to the progress of the wildebeest.
The
rivers and indeed the few isolated lakes in the
south of the Serengeti, are terrifying to the
wildebeest firstly because of the animals’ fear of
the water itself and the creatures it may hide, and
secondly because water generally means vegetation,
and thickets that may conceal predators. Yet the
wildebeest have an inherent instinct to trek in a
certain direction at any cost – despite their
terror. The lakes in the south – Ndutu, Masek and
Lagarja – for example, are little more than a few
kilometres long, and could easily be walked around.
But natural selection steps in once more: the
wildebeest that crossed the lakes in previous
generations survived to breed, so the waters pose no
fear to their progeny; those that did not make it
gave no further input to the gene pool.
In
his definitive documentary on the migration, The
Year of the Wildebeest, filmmaker Alan Root
describes how he watched a crossing at Lake Lagarja,
where, once the main body of the herd had crossed
cows that had become separated from their calves
turned back to look for them re-entering the water
and swimming back. On reaching the other side, still
not reunited with their offspring, they turned back
once again. This toing and froing went on for seven
days, until eventually the numbers of arriving
wildebeest built up again and the stragglers were
forced to move on with the main body of the herd.
Thousands of wildebeest died in the lake that year.
While such tragedies may appear to be a disaster for
the wildebeest, the deaths only represent a mere
handful of the hundreds of thousands of calves born
each year. Without a degree of natural mortality,
the wildebeest population could spiral out of
control.
Wildebeest arrive at the Mara River in their tens of
thousands, and gather waiting to cross. For days
their numbers can be building up and anticipation
grows but many times, for no apparent reason, they
turn and wander away from the water’s edge.
Eventually the wildebeest will choose a crossing
point, something that can vary from year to year and
cannot be predicted with any accuracy. Usually the
chosen point will be a fairly placid stretch of
water without too much predator-concealing
vegetation in the far side, although occasionally
they will choose seemingly suicidal places and drown
in their hundreds. Perhaps, once again, this is
because crossing places are genetically imprinted in
the minds of the animals.
Some
fords do attract larger numbers of animals than
others though, probably because they’re visible from
a greater distance and the arriving herds are able
to see others of their kind either in the process of
crossing the river or grazing on the lush grass on
the far side.
The
Predators
Once
on the grasslands of the Maasai Mara, the wildebeest
spend several months feeding and fattening once
more, taking advantage of the scattered distribution
of green pastures and isolated rainstorms. A
remarkable feature of their wanderings is their
ability to repeatedly find areas of good grazing, no
matter how far apart. The physiology of the
wildebeest is such that it ahs been designed by
evolution to travel large distances very quickly and
economically, apparently requiring no more energy to
run a certain distance than to trudge along at
walking pace. Every facet of its life and behavior
is designed to save time – wildebeest even mate on
the move, and newborns are, as we have seen, up and
running in minutes.
While the wildebeest are drawn into migrating by the
needs of their stomachs, the fact that they’re
constantly on the move has the added benefit that
they outmarch large numbers of predators. The
predators are unable to follow the moving herds very
far, for many are territorial and can neither
abandon their territories nor invade those of
others. Moreover, the young of most predators are
highly dependent upon their mothers, who can’t move
very far from them.
Closing The Circle
By
late October, when the first of the short rains are
falling on the Serengeti’s short-grass plains,
filling seasonal waterholes and bringing new flushes
of growth, the wildebeest start heading south again.
The herds trek down through the eastern woodlands of
the Serengeti, some 90 per cent of the cows heavy
with the new season’s young. Tightly grouped as they
pass through the wooded country the wildebeest
scatter and spread out again once they reach the
open plains. |