NARRATOR: The Serengeti Plains, East Africa,
1.3 million animals are about to embark on the most epic migration on Earth,
the single greatest mass movement of land mammals on the planet,
as they chase the African storms in search of rain-ripened grass.
It's a journey fraught with danger.
More meat eaters hunt, kill or scavenge these savannahs
than almost anywhere else in Africa.
And whenever the herds arrive,
they herald a frenzy of feeding unparalleled in nature.
This is Africa's great wildebeest migration
as you've never seen it before...
The halcyon days for Africa's predators.
NARRATOR: Tanzania, Central Africa.
As seasonal storm clouds have watered
the vast grass plains of the southern Serengeti,
they've brought the grasslands to life
and ushered in the greatest concentration of grazing animals on the planet.
Yet, the 1.3 million wildebeest haven't come just for the lush grasslands.
It's early spring
and one of the most significant events in the wildebeest calendar
is about to take place.
Wildebeest birth is a quick process.
This is a dangerous time for both mother and her unborn calf.
With one last push, a new runner joins the herd.
Over the next three short weeks
around a quarter of a million calves will be born,
90 percent of all the births of the year.
With 500 born every hour,
this must be one of the world's greatest population explosions.
Wildebeest calves learn to stand faster than any other mammals.
Their lives depend on finding their feet as quickly as possible.
(GROANS)
Within just one day,
the calf will match his mother for speed and agility.
It's an ability written in its DNA, as from now on,
it'll be running for its life in the greatest race on Earth.
Around a quarter of those calves won't survive their first year
and the migration to come.
They're on the hit list of nearly every African predator.
Many calves don't even make it to the start of the great race.
This calf probably suffocated on its first and final journey into the herd.
On the plains of Africa, nothing goes to waste.
With a wingspan of two-and-a-half meters,
the lappet-faced vulture is the largest scavenger here.
Wings outspread, in what is known as a threat walk,
the bird bars the carcass from its competitors.
Only when they've made an opening
will the griffin and white-backed vultures,
or the marabou storks, get a look in.
They'll make quick work of the carcass
and, by dusk, little will remain of the remains.
A grim end to a short life.
(SCREECHING)
(FLIES BUZZING)
The diffused light of dawn reveals another tragedy.
A lioness has killed an adult bull in the night,
and concealed it in the shade of an Acacia tree.
(FLIES BUZZING)
It's no coincidence
that the lions of the short grass plains in the southern Serengeti
choose this time to raise their young, too.
And judging by the size of their bellies,
her cubs haven't missed out on the meat course, either.
(FLIES BUZZING)
The mother wildebeest now form nursery herds
where the calves can learn to play.
Play is good practice for the migration to come,
but they never stray too far from their mothers.
A wildebeest calf is reliant on its mother for food,
protection and guidance throughout its first year.
The soils in the southern Serengeti
are richer in calcium, potassium, sodium and phosphorous
than anywhere else on the wildebeest migration route.
Absorbed by the grass and passed on to the calf through the mother's milk,
these minerals help build strong bones and muscles.
This concentration of minerals
may be one of the reasons why the wildebeest choose to give birth
on these short grass plains in the first place.
The grassland is now being grazed hard.
And the by-product is something
that one enterprising animal has evolved to exploit...
Dung.
The wildebeest herd drops an estimated 420 tons every day.
There are over 100 different species of dung beetle in the Serengeti.
They spend their days on the lookout for fresh droppings.
When they find them, they fly in and build a ball.
Standing on its head,
it'll roll the dung away with its back legs.
These amazing animals move up to 75 percent
of all the dung dropped on the Serengeti,
and 20 percent of the soil here is fertilized by buried balls.
An underground larder of food for the beetle and its grubs.
Though it seems a smaller beetle is intent on stealing from its rival's ball.
Without dung beetles,
the Serengeti would quickly become unlivable.
Throughout the spring,
the wildebeest herds stock up on the grasses of the southern Serengeti,
but they never really stop moving
as they scour the plains for fresh pasture.
And it's this gradual ebb and flow of animals
that ultimately ushers in the great migration.
There's no set start time, and no set route,
but gradually, an incredible 90 percent of all the grazing animals
that once filled the short grass plains of the south move on.
Wildebeest have scent glands in their feet,
so head down,
it's a relatively simple process to follow the leader.
An epic journey
that will take the wildebeest up to 1,000 miles has begun.
And, for the next two months, they'll barely stop walking.
It's now mid-summer, and after 60 days on the move,
the animals have reached a turning point in their migration.
The plains are awash with testosterone as the wildebeest prepare to mate.
Charging at full speed,
the bulls butt heads and establish their dominance.
Rutting is such an all-consuming test of stamina, strength and endurance
that over the next three weeks the bulls may not feed at all.
Mating itself takes just a few seconds,
yet wildebeest have one of the most successful sexual practices
of any mammals.
And despite its brevity,
an estimated 95 percent of females will become pregnant during a rut.
In the process,
the strongest males have ensured their genes
are the ones passed on to the next generation of migrants.
The wildebeest migration around Africa's Serengeti
is the most awe-inspiring natural event on the planet.
1.3 million animals on an endless march.
It's now late summer,
and the wildebeest have reached the northern border of Tanzania,
gateway to the lush grassland of Kenya's Maasai Mara.
But one obstacle lies in their path...
The mighty Mara river.
There are no easy fording points here.
The water, flooded rapids,
deep, fast flowing, and filled with crocodiles.
The river banks, cliffs up to 20 meters high.
It's a seemingly impenetrable barrier...
And for many days, the herds amass on the bank.
Soon, tens of thousands of animals line the water's edge.
As pressure on the bank continues to build,
there's nowhere left to run.
The animals jostle for space and a calf is pushed over the edge.
The rest follow and the stampede is on.
There's no stopping them now.
Launching headfirst into the river, the wildebeest take the plunge.
A high jump gives the wildebeest a head start.
A dive-in that might help them avoid the attention of crocodiles
who could be lurking beneath the water along the shore.
The current is powerful, and the herd are pushed downstream,
but wildebeest are strong swimmers with the vigor to make it across.
A hippo defends her territory and her calf.
This is her river.
Hippos don't like having their space invaded.
Bigger threats lurk beneath the surface.
The Mara is home to some of the largest crocodiles in Africa.
The front runners of the herd have now reached the other side,
but the bank is rock and as slippery as ice.
It's turning treacherous and the animals struggle to make it up.
There will be many rivers to cross during their stay in the Maasai Mara,
but for now, soaking and exhausted,
the wildebeest emerge triumphant on to the green savannah.
This is what they've been marching for...
A promised land, nirvana for African wildlife.
The Maasai Mara is so productive at this time of the year
that from late summer through autumn,
the animals will stay put, stock up and regain their strength
on the most prevalent plant here...
Grass.
Each grazer has evolved its own way of feeding on it,
and the Mara's predators have evolved their own ways of hunting them.
Zebra, with their rounded mouths, graze on the main parts of grass...
The tall and fibrous, upright shoots like hay.
They have evolved very acute senses of smell and vision,
and that means predators must use stealth to catch them.
Wildebeest don't compete with zebra for food.
They use their flat, wide mouths to graze deeper and on finer shoots,
cutting the grasses off right at ground level.
Around 150,000 Thomson's gazelle
complete the migration each year alongside the wildebeest.
They don't compete with the larger grazers for food,
because, with their delicate mouths,
they can fish out the shoots the others leave behind.
Their small size does make them appealing prey though,
and one of Africa's big cats has evolved its own way of catching them.
(FLIES BUZZING)
Cheetah may be the fastest animals on land,
but it's a close race,
and the fastest, most agile gazelles can survive the chase.
Stotting, or leaping into the air,
is a way for other gazelles to tell the cheetah they've seen it too,
so there's no point in pursuing them.
Gazelle calves could never outrun a cheetah, so, instead,
they lie down, lie still and hide in the grass.
It doesn't always work.
This calf is destined to be removed from the gene pool.
There is one grazer here that few predators would attempt...
Elephants.
They'll use their feet to kick up great clods of grass,
brushing the soil away before eating the plants, roots and all.
The Mara's grazers co-exist,
thanks to the different ways they feed,
and the result is perhaps the most diverse assemblage of large animals on the planet.
(THUNDER RUMBLING)
The Maasai Mara receives more rain than anywhere else en route,
averaging over one meter per year.
Rain is the essence of the wildebeest migration,
the driving force of their great trek.
Most of that water falls in the three month period
when the migration is in town.
This is the Mara's wet season.
There's little shelter,
so the animals line up facing away from the deluge.
All that water has to go somewhere,
and the result is a series of brooks and streams that crisscross the plains.
Tributaries of the Mara river, they form homes for pods of hippos.
(SNORTING)
Although not as fast flowing, wide or deep as the mighty Mara,
for the wildebeest approaching water like this,
the Talek river is always risky.
There's safety in numbers,
so the herd waits to reach critical mass before crossing.
They graze oblivious to the danger on the other bank...
Lions.
Urged on by instinct,
a few animals take their first tentative steps across the water.
One of last year's calves is taken.
This truly is nature, red in tooth and claw.
Finally, a death grip to the muzzle and the wildebeest is suffocated
out of his misery.
The herd run on.
They can never be sure whether there are other lions in the area.
For a lone lioness, only one in five hunts is ever successful.
Yet working together, they can bring down their quarry a third of the time.
They'll now gorge.
They'll consume up to a quarter of their own bodyweight
in flesh in one sitting.
They must eat fast.
In lion society it's the king that rules,
and the male and the rest of the pride are not far behind.
He's a third larger and a third heavier than the lionesses,
and he'll take the lion's share.
(ROARS)
Only when the male's finished feeding will they return to the carcass.
For the wildebeest herd, there's no time to rest.
Lions are just one of the dangers they must face.
The Maasai Mara is home to what could be one of the highest densities
of big predators found anywhere in Africa.
Cheetahs.
These three brothers have been patrolling the Mara for the last three years.
Male cheetahs often form alliances for life.
Their territory stretches across large sways of the Maasai Mara,
and they'll cover tens of kilometers in a day on patrol.
They do have favorite spots...
Vantage points, from where they can survey the plains.
Here, they'll rest...
...and leave scent markings and droppings on promontories.
Signposts telling other cheetahs they're in the area.
With no herds in sight, the trio relax.
As the sun sets over the Mara, other predators are on the prowl.
(HYENA HOWLING)
Spotted hyena.
They choose the dim confusion of dusk
to switch from reputable scavenging to coordinated hunting.
Hyena are the most numerous big predators on the Mara.
Their clans can reach 80 animals strong,
and this strength in numbers ensures a kill almost every night.
They circle the wildebeest looking for their best chance.
Hyenas have an extremely well developed sense of smell and hearing,
and excellent night vision.
They're on the lookout for the sick, starving or weakest individuals.
One hyena breaks away.
The hunt is on.
She dives into the herd, singling out one of this year's calves.
Hyenas may travel 80 kilometers from their den in search of food,
and, when hunting, their endurance is key to their success.
Their victims, unable to keep up with the hyena's staying power,
end up being run to exhaustion.
The calf is driven into the open.
Here, the rest of the clan is waiting.
Hyenas have the strongest bite of any mammals,
and can easily chew their way through solid bone.
The calf's fate seems sealed.
Then, something incredible.
A hyena from a rival clan bears down on the prey.
The pack breaks away.
Hyena won't tolerate a rival on their patch,
and they can always catch another calf.
Battered and bruised, and no doubt, terrified,
the calf staggers to its feet and races off to rejoin the herd.
It's been a close shave.
The early morning light of dawn reveals the hyena were lucky in the night.
They managed to bring down another wildebeest calf.
Now, they've got to keep it.
Jackals, vultures, marabou storks,
are always on hand to steal what morsels they can.
But there are bigger scavengers on the lookout this morning...
A young male lion.
His pride hasn't been so successful and they're hungry.
In a reverse of popular perception,
the lions now turn scavenger,
and attempt to drive the hyena off their kill.
It's a standoff.
The lion may be the biggest cat in Africa,
but faced with overwhelming numbers,
they stand little chance of stealing the kill away.
The three male cheetahs haven't moved far from their vantage point in the night,
and they're hungry.
Cheetahs usually hunt alone for small prey,
but working as a team,
this trio hope to secure something much larger.
The herd edges ever closer to the cheetahs.
The three crouch down, like runners on the starting blocks,
hiding in the just long enough grass.
Heads down, waiting for the wildebeest to approach,
the cats play cat and mouse on a large scale.
A waiting game, they hope.
Lie still, lie hidden, keep watching
and let the prey come in.
A lone cheetah would have little chance against an adult wildebeest.
It weighs more than all three cheetahs put together.
So teamwork is the only way to success.
The wildebeest come within range.
It may have looked chaotic,
yet slowed down,
the hunt had almost military-like precision.
First snipers, perfectly still, they keep watch,
singling out their target.
Second, springing from the ground like lethal mortar bombs,
they cause panic and chaos in the herd.
Cheetah are the fastest animals on land,
and can accelerate from 0 to 50 in just three seconds.
Third, two cheetahs split mother from calf, separating them.
While the third cheetah aims for the kill,
deftly tripping the calf with his front paw.
Yet the wildebeest aren't without defense.
The mother charges in, risking her own life to save her calf.
Back on its feet, it's running for its life.
The second and third cheetah now return,
once more separating the wildebeest and isolating the calf.
To aid its sprint, the cheetah's feet are equipped with blunt claws
that act like spikes on running shoes.
Unique amongst all cats,
the claws can't be retracted into a sheath,
instead, they're always out and ready to run.
And game over.
Once the prey is on the ground, its fate is sealed.
Death by asphyxiation.
Cheetahs may be the fastest animals on land,
but there's a drawback to that speed.
It raises their body temperature to near fatal limits,
as muscles produce heat 60 times that of a cheetah at rest.
In large numbers, vultures can intimidate cheetahs off their kills.
Having had their fill,
they'll move off in search of water and shade.
The scavengers will waste little time stripping what's left of the carcass.
The cats pause to clean off the blood of victory.
It's been a successful morning.
Wildebeest are built to walk,
and the truth is their migration never really ends.
Instead, they track a path around the Serengeti
in pursuit of Africa's rain-ripened grass.
And as the seasonal rains move south,
the herds must follow,
and that means once again crossing the Mara river.
Year after year,
the wildebeest have chosen one spot to cross as they leave the Maasai Mara.
The most direct route south.
Getting restless, agitated, they start to approach the water.
Nervously, tentatively, they edge forward,
sniffing the ground as if checking for crocodiles.
The zebra are first to go in.
They have more acute senses than the wildebeest,
and often lead the way at crossings.
The wildebeest follow.
This is what the crocodiles have been waiting for.
They seem to select particular animals.
Those at the edge of the herd are favorite.
Like torpedoes, they home in on the weak, injured or young calves.
Their strategy...
Use their own bodyweight to drag their unfortunate victims under
and drown them.
Crocodiles have the strongest bite of any animal.
An incredible crushing force of 340 atmosphere per square centimeter,
compared to just 10 for man.
And measuring six meters, they're totally unstoppable.
The calf's oblivious to the danger until it's too late.
And still the herds keep coming.
The forward momentum of the crossing
draws the remaining animals off the plains.
A lioness.
The herd is spooked.
The lioness won't risk an attack until the wildebeest are within 10 meters.
But now, she has a chance.
A calf is taken down and dragged into the scrub.
The stampede continues...
The animals running in chaos.
Like a shoal of fish,
wildebeest seem to know that the middle of the herd
is the safest place to be, and jostle for safety.
Using the low scrub for cover, another predator, a leopard, approaches.
Leopards are stealth hunters, masters of surprise.
Ambush is their way of life, and chaos, their best chance.
Grabbing the calf by the neck,
she bites down on its windpipe and tightens her grip.
At 45 kilos, she weighs a little less than the calf,
but she's much, much stronger and more agile.
She uses her bodyweight to grapple the calf to the ground.
Now, with surgical precision, she crunches at the neck,
crushing the wildebeest's windpipe.
With a turn of her head, she blocks the airways.
One last spasm, and death takes a grip on the calf.
Leopards are among the smallest members of the big cat family.
So to prevent her kill from being taken by lions, hyena or other scavengers,
she now drags it away to a safe hiding place near the river.
Back in the river, it's bedlam
as tens of thousands of animals try to make it up on to the other side.
The banks are steep and slippery,
and there are few places where the animals can make it out.
The river is so packed with wildebeest,
even the crocodiles can't get out of the way.
Yet still, the hunt is on.
The zebra herd have made it across.
The crocodiles approach.
One zebra panics and tries to head downstream,
but there's no way out down there.
Trapped by a vertical slippery wall of mud,
the lone zebra's fate seems sealed.
On the bank above, the rest of the zebra herd wait,
braying, watching.
A fallen tree blocks the zebra's path.
The water's deep, it's tired,
it can barely keep its head above the surface.
In just a few days of river crossings, over 10,000 animals can die.
Most are not taken by the lions, leopards or crocs,
they're trampled on, drowned, or simply die of exhaustion
trying to find their way out of the water.
Then somehow,
the zebra finds a way through and up the bank to the waiting herd.
The crossing point is quiet now,
yet, it's littered with the remains of the dead.
The predators feed on the spoils.
This may be the last easy meal
they'll have until the herds return in a year's time.
In the water, the crocs are feeding, too.
Crocodiles have no chewing teeth, so they work together,
taking it in turns to hold the carcass while rolling to rip off chunks of flesh.
They'll swallow it whole.
A crocodile's stomach acid
is one of the strongest found in any animal.
Strong enough to dissolve bone.
And even the wildebeest's horns.
And they can consume half their own bodyweight in food
in one sitting.
They'll make do with fish for the rest of the year,
now the wildebeest have gone back south.
On the bank above, the cub has joined the leopard mother.
She's stashed her kill at the base of a tree,
and it's time for them to feed.
The cub is too young to hunt for himself,
but he'll investigate the carcass and play whilst the mother eats.
Play helps him learn how to kill.
The herds have started their long march south,
back to their birthing grounds
on the short grass plains in the Southern Serengeti.
It's an epic journey that's been repeated for perhaps a million years,
but for how much longer?
In 2010, the government of Tanzania
revisited plans to build a major road across the Serengeti.
No doubt a profitable trade route,
it could block the course of the animals
and prevent the annual influx of prey the predators depend on.
It could be the end of the road for the wildebeest migration.
For now, the road is on hold and the wildebeest march on.
By the time they arrive in the south,
they may have walked 1,000 kilometers this year alone.
They've survived attacks by lions, leopard, cheetah and hyena,
braved crocodile-infested river crossings
and still, instinct written in their DNA keeps them moving.
Wildebeest live lives of perpetual motion.
They bring life to the Serengeti.
And for the time being,
the great migration remains the most awe-inspiring epic in nature.