The savannah...
it is the Africa of our imagination...
vast lands, home to the greatest herds on earth...
It looks timeless... but it isn't.
This is a young landscape created by remarkable events.
Now we can see the big picture.
Seen from space,
Africa is dominated by great swathes of desert and rainforest.
Caught between these extremes lies a band of grasses
and dry woodland - the savannah...
It's incredibly fickle.
In the space of a few years,
a sprinkle of trees can turn into thick woodland...
...or disappear altogether... leaving just grasses.
The life of the savannah is dictated by the weather...
and it's highly capricious.
Every year there is a dry and wet season,
but no two years are exactly the same.
In drier times, grasses thrive...
...with heavy rain, it's trees that flourish.
The savannah is the fastest-changing and
most unpredictable of all African environments.
Yet somehow it manages to support an incredible collection of life.
It is the haunt of the big cats...
...but these elegant hunters are outnumbered...
...the herds so vast, they beggar belief.
More animals live here than anywhere else on earth - the question is why?
To find out, we've got to go back to the days before the savannah was born.
For millions of years rainforest dominated much of tropical Africa...
and then things changed.
The climate began to dry, large patches of rainforest died,
replaced by thickets and grassy spaces creating new food opportunities.
Pioneers were quick to move in to the infant savannah.
Some of the first were the ancestors of the giraffe,
who left the dwindling jungle.
And from the desert came others.
Antelope thrived here and in great numbers.
For them the savannah was a paradise,
offering lots of easy-to-reach food.
Some plants did fight back.
Acacia probably developed thorns to limit the damage caused by giraffes.
Over time, many bushes and trees were pruned and clipped
by an onslaught of nibbling mouths.
And then, three million years ago,
another animal marched in from the rainforest...
to become one of the greatest architects of all.
Destructive yes... but also creative.
Many different types of plant eaters were transforming their world...
and on a grand scale.
By trampling and breaking up bushes and saplings,
something even more special was created...
...the beautiful open country we see today.
Only five to seven million years old,
savannah is the youngest habitat of all...
Africa's new world.
No other landscape has been so dramatically shaped by its animals.
In a few places, the great herds still run free...
offering a glimpse of how things must have looked before the time of man.
In the shadow of the great herds... came the hunters.
Dramatic contests like these are part of everyday life on the open plains,
but everything here is controlled by a far greater force
the grasses themselves.
Grasses are so adaptable, resilient and fast-growing,
they provide important bulk food.
Wildebeest eat nothing else,
while most other vegetarians eat grasses at some time of the year.
Food for the mighty...
...and the miniscule.
Despite the hordes of different grazers, grasses don't really suffer.
With regular pruning, the more robust are controlled...
allowing a greater variety to thrive.
Not only that, but by cutting back the grasses,
the grazers also encourage them to grow faster...
It's like mowing the lawn... the biggest lawn in the world.
Life is lived to its limits here...
and it's the humble grasses that fuel all the action.
Grasslands can be so productive that for some birds,
like European white storks,
they're worth flying half way across the world to reach.
The skies also fill with great flocks of terns.
They've all made this marathon journey for one reason...
huge numbers of grass-eating army worms.
There's so many that they even feed a giant among birds
the marabou stork.
Such a population explosion of army worms only happens every ten years or so
and it's when just the right humidity encourages
just the right amount of grasses to flourish.
Because feasts like this are sporadic and moveable,
storks have had to develop into long distance commuters...
...but these gatherings, built on grass leaves,
are minor compared to those drawn in by the seeds of grasses.
They're so nutritious,
they attract their own crowds and they are breath-taking.
Red-billed quelea.
In some years,
the rain encourages so much grass seed in just one locality
that the birds reach breeding condition quickly.
The result?
One of the savannah's most fabulous sights a nesting colony of quelea.
Crammed into a tiny patch of woodland are over a million breeding pairs.
The chicks are out of the eggs in just ten days
faster than any other bird in the world.
All this commotion attracts marabou storks.
For a short time, they can enjoy easy pickings.
Quelea reproduce at a phenomenal rate.
Their population more than doubles in just one month.
But they can only breed in these numbers
when there's enough grass seed available.
It can be famine or feast in this unpredictable world.
Both quelea and wildebeest move through the savannah in enormous numbers,
but there's another species whose numbers are higher still
and they're here all year.
To find them, we must travel into the night.
They're... termites.
And there are so many that they provide food
for one of the savannah's most voracious feeders.
An aardvark a shy creature and very rarely seen.
Male aardvarks can weigh as much as a full grown man...
...And all on a diet of ants and termites.
His impressive bulk shows just how many there must be...
...up to 10,000 per square metre.
So what keeps these going?
Grasses, leaves and dead wood.
Every year, ants and termites consume a third of all the plants in the savannah
and that's more than the elephant,
wildebeest and zebra combined.
But sometimes it can take an aardvark an hour or two to sniff out a nest.
The underground colonies can be far apart.
Aardvarks go to all this effort because they need to eat a lot of termites
somewhere in the region of 100,000 every night.
Termites not only feed aardvarks,
they also benefit the whole system by recycling nutrients
and this helps everything...
...from common grass rat to rare wild cat.
Spring hares are alert to the slightest sound or hint of vibration.
So much potential prey brings out serval cats
whose keen hearing makes them master night hunters.
Although aardvarks hoover up lots of termites,
eventually the defending soldiers deter even the most determined.
And every year, at each colony on just one magical night,
couples take to the air looking to start their own nests.
Savannah can be bountiful... but there are times of hunger too.
The dry season can last eight months or even more,
testing the survival skills of everything that lives here...
so how do they cope?
The Serengeti wildebeest have evolved a death-defying strategy.
Since they need green grass all year-round,
they must follow the rains...
Every year, they move north to south,
to east and west, and back to north
a circuit of more than 1500 kilometres.
It's an epic journey.
Herds of elephant also migrate.
Adults and their babies can march for three days without water.
These animals have to move
they'd simply starve to death if they stayed put.
In this open landscape,
animals can see and smell storms from many miles away.
And in their search for fresh grass,
nothing will stop the wildebeest from going there.
Such is their drive for fresh grass that the wildebeest even mate on the move.
The females and young keep on walking
while the excitement among the males grows.
In such a melee, its vital for breeding males
to catch the eye of passing females so they dance,
bellow and grunt to ensure they stand out in the crowd.
It's a tiring time as they fight off rivals
and try to woo females onto their little plot.
Fighting and mating is repeated again and again
until most of the females are pregnant
and the males are exhausted.
The mating is over in just two to three weeks
and the relentless journey continues.
But not all animals are able to migrate.
In the woodlands on the edge of the grassy plains
live animals who can't travel far.
Buffalo are big and bulky and they must drink every day.
Normally they can cope with the poor quality grasses
in the dry season
but, in extreme years,
the grass becomes too poor even for them.
As they starve, lions close in.
Despite the buffalo's weakness, it's still a clash of the titans.
Lions dominate by strength rather than numbers.
In fact, they're more rare than you might expect.
For every 800 plant eaters, there's probably only one lion.
Like buffalo,
lions aren't built to walk miles in search of food
and their cubs can't travel far at all until they're at least a year old.
Stuck in one place, a lion pride is tied to a territory
where their future depends upon what they can catch in the leanest of times.
As food gets scarce,
the females' milk dries up so the first to suffer are the cubs.
Sometimes whole litters die.
Lions and buffalo have evolved the stamina to cope with most droughts.
But occasionally they can be very severe indeed
especially when vital rain clouds
from the Indian Ocean are pushed off course by changes
in weather patterns as far away as South America.
Then everything struggles...
acacia roots plunge down 30 metres to tap water deep underground.
But in the really dry years, the fight is too great...
living trees fade away...
If the dryness persisted eventually
even the toughest savannah grasses would perish...
turning the land to desert.
When the rains finally arrive, life springs into action.
In some years,
the rain is so intense that the advantage swings
back to moisture-loving trees.
And with a run of real wetness,
the rainforest would be quick to reclaim the land.
The savannah seesaws between grassland and woodland.
The changes can take a few years or... be more sudden.
The beauty of savannah is that it responds so well to change...
and change creates variety.
The sweeping patchwork of plains, woods and thickets offers shelter,
shade, water-holes, and a wide range of food...
somewhere there's bound to be a safe and bountiful haven for animals...
whatever the weather.
Such a varied landscape has done one more thing
it has encouraged animals to be adaptable.
And lands as diverse as these have seen one group of animals
become the masters of adaptability.
To tell their story, we must travel back in time
to when one primitive group of primates took up the challenge of the savannah.
These were the ancestors of today's baboons.
When the ancient forests were shrinking,
fruit became a highly prized commodity.
To get by, baboons developed into experts at eating unripe fruit
even if it wasn't always delicious.
Being able to exploit the meagre supply quicker than most,
allowed baboons to move further away from the forest edge
and well out into the savannah.
Here they developed a taste for all sorts of food
including meat, whenever they could get their hands on it.
If only they'd been able to walk upright,
they might well have taken over the savannah.
But that was left to another omnivorous primate
who evolved very much later.
Just under 2 million years ago,
our distant ancestors surged ahead to control something truly elemental.
The use of fire helped to give them the upper hand.
Cooking made food easier to digest and therefore much more nutritious,
helping to fuel bigger brains.
Further development was rapid...
and fully developed humans were probably
in the savannah six thousand generations ago.
Their hunting skills were refined over millions of years
giving their savannah prey a chance to develop ways of evading them.
As well as fuelling development,
fire also helped humans to mould the savannah to their liking.
Fire clears away dead grass and opens up the bush making it
easier to spot dangerous animals, like snakes and buffalo.
Cattle were introduced to savannah some 5,000 years ago.
Keeping livestock and growing food meant
that farmers and herders used fire even more...
Burning opens up the land for cultivation
and encourages the growth of fresh green pastures for cows.
And today with a growing human population,
people are looking for room to expand and they're looking for it here.
In these lands of boom and bust,
large settlements of people may be bad news.
Savannah always has the potential of turning to desert - and staying there.
And, given that an area almost the size of Australia goes up in flames every year,
the impact of people is already enormous.
The savannah lands we see today have been shaped by animals and people,
and created by geology and climate.
Change and variety are at the heart of life here.
This, plus the fast,
efficient cycling of nutrients helps explain
why so many animals are found in these vast lands - and nowhere else.
But there's another critical reason: The huge size of Africa.
Just over 30 million square kilometres
Africa is nearly twice the size of South America
and it's this that's helped buffer the continent
from violent climatic change
preventing recent ice ages from subduing life in these huge lands.
And looking to the future
space may well be the key to the survival of these vast numbers.
Savannah animals, more than most in Africa, need space.
Space to follow the rains.
And space to make the most of the fickle and ever-changing opportunities here.
The birth of Africa's newest world
is the result of a remarkable chain of events.
For cheetah, gazelles and all who live here,
it's still changing... every season of every lifetime.
The savannah is a miracle of change and regeneration...
...dynamic, exciting, and exuberant.