Original subtitles

[dramatic instrumental music playing]

[narrator] Twenty years of drought

have turned the Boteti river in Botswana to dust.

The animals that live here have to endure season after season

of excruciating hardship just to keep alive.

To survive in this harsh desert,

they've had to adapt their behavior.

[thunder rumbling]

But now, the long and dry era is about to change.

Water floods the dusty river bed.

Desperation gives way to hope

as the Boteti flows once more.

[zebras yipping]

[birds chirping, flies buzzing]

[instrumental music playing]

The Boteti river is a jagged lifeline that runs into a harsh desert.

It connects the lush water wilderness of the Okavango

with the fickle wastelands of the Makgadikgadi pans.

For centuries, the floods of the Okavango have spilled into the Boteti,

and brought the desert to life.

[bird calling]

But over the past few years, this supply has gradually dried up,

and what was once a former paradise,

has become a killing field.

Herds of zebra fight over what little water is left.

[ominous music playing]

[elephant trumpets]

[zebras yipping]

These last pools are their dry season lifeline.

But they're not the only creatures struggling in this harsh environment.

[insects buzzing]

Surprisingly, some crocodiles still survive here.

They were stranded in this area when the river stopped flowing.

Crocodiles need warm sun and cool water to regulate their body temperature.

But these shallow pools are lukewarm.

[bird calling]

So the crocodiles have devised an ingenious way to lower their temperature.

They have dug caves in the dry river bank,

where it is ten degrees Celsius cooler than the outside.

[zebra yipping]

Crocodiles can walk over land, but they can't cover distance.

The next closest water is the Okavango Delta,

eighty miles to the north,

too far for these short-legged reptiles,

[birds calling]

making them long-term prisoners of the Boteti.

[insects buzzing]

But over the years of drought

these crocodiles have not only learned to keep cool,

they have completely changed their hunting behavior.

They now focus on an unlikely food source.

[queleas twittering]

Huge flocks of queleas converge on the Boteti pools.

Strength in numbers is a popular strategy,

but sometimes, flocking is deadly.

The birds are also thirsty,

and they descend on the water's edge in force.

The collective weight of the tiny bodies bend the reeds,

pushing some of the queleas into the water.

The crocodiles persist

and eventually make a full meal of the tiny birds.

Waterlogged survivors paddle for the shore.

But a lurking marabou is waiting to pick them off.

[birds calling in the distance]

[instrumental music playing]

Evaporation is at its highest now

and the pools are becoming muddy shallows.

[zebras yipping]

For one female zebra, the situation is becoming increasingly desperate.

She's early in her pregnancy

and she'll eventually need fresh, green grass to supply her unborn calf

with milk when it arrives.

[zebra snorts]

[rhythmic music playing]

Water along the Boteti is so scarce that every pool is a sought after commodity.

Elephants are clever in their use of the precious water.

When they drink, they don't waste.

They step carefully into the pool to avoid lifting the mud from the shallows.

They need 250 liters a day,

so they have to think ahead.

They move further down the dry riverbed.

The elephants create mud by stirring up the water with their feet.

The mud cools them, and gets rid of parasites.

[elephant trumpets]

But it's sometimes difficult for them to haul themselves out.

The last part of their daily routine, is a sand bath.

A sprinkle of fine sand cements the mud

and provides protection from the sun.

Unlike most of the other animals,

these elephants can range into the adjacent desert to find nutritious food.

They hunt down certain twigs and barks that nourish their huge frames.

But their favorite parts are the leaves.

At first glance, the foliage of this winter wilderness seems barren.

But acacias have a way of drawing every drop of moisture from the soil

to keep their tiny leaves alive.

Sooner or later, though,

the herd will have to return to the river,

and sometimes they roam further than they intended.

They get thirsty and have to run back.

[zebra yipping]

But the water hole is overcrowded.

[zebra snorting]

Every animal needs to drink.

[soft instrumental music playing]

[yipping continues]

The pregnant mare is in the queue,

patiently waiting for access.

The front ranks become agitated and churn the water into mud.

This sounds the alarm for the elephants.

-[elephant trumpets] -[zebras yipping]

They know that this water needs to be saved.

But churning it into mud,

will mean far less to drink.

[elephant trumpets]

Eventually, they take charge.

[yipping continues]

They cannot let the unruly zebra destroy this precious waterhole.

[elephant trumpets]

[insects buzzing]

More and more zebra come to drink at the river.

[instrumental music playing]

But the stagnant pools have a welcoming committee.

The vultures have worked out

that every animal in need of water has to come to the Boteti.

Right to them.

They know many are already on the verge of death.

All they have to do, is wait.

Jackals are clever.

[jackal barks]

They follow the throng of scavengers.

There may be something in it for them.

[ominous music playing]

Eventually, their patience is rewarded

as a zebra collapses.

[instrumental music playing]

[water splashing]

[hippos grunt]

Like the stranded crocodiles,

hippos are also heavily reliant on water.

And this, their last polluted pool,

is drying.

And hardening.

In the cool of the night, they're free to feed in the surrounding scrub.

But when morning comes,

they have to return to the cool of their last wallow...

[hippo huffs, grunts]

hoping that there's enough mud to coat their sensitive skins.

This remaining pod hasn't raised young for years.

All calves are killed immediately at birth by the pod male.

There just isn't room for one more.

The hippos are also long-term Boteti inmates.

Another season like this, and they'll be cemented in their muddy tomb forever.

[flies buzzing]

By mid-morning, the scavengers have reduced the fallen zebra

to a pile of skin and bones.

One creature's famine, is another's feast,

and the jackals join in.

[bird calling]

They've left their territories out in the desert.

[vultures screeching]

But like a Cold War meeting in no-man's land,

this encounter is not friendly.

[jackal growls, barks]

They compete with each other

for every bite.

[vultures calling]

[bird calling in distance]

While some jackals work the Boteti pools,

fifty miles into the desert, others have a different survival plan.

[insects buzzing]

Without the summer rain, these plains are dry and dusty,

but this hardy individual can spend the entire year out here.

It knows that where there's old elephant dung, there are insects.

To find them, it has to listen.

It focuses on sound,

pinpointing the location.

It gets all the nourishment and moisture that it needs from this food.

But even out here

it has competition.

The meerkat family comes out of their den in the morning to forage for insects.

which they dig out with their long, strong nails.

They hunt for food together,

alternating sentry duty.

[guitar music playing]

They don't share their catch,

but eat it there and then.

The saviors of this desert environment are termites.

They're the favored food of many insect eaters.

These primitive animals form huge, well-organized colonies that go deep underground.

Harvester termites feed on any vegetable matter.

And when the grasses dry out, it's time to harvest.

The blind workers spread out over the plains

and efficiently clip the grass blades

which are taken underground to store.

A wolf spider has strategically set up home near the termites' nest.

Because they cannot see,

the termite don't even know she's on the prowl.

[suspenseful music playing]

She hunts during the day

and has a well-developed set of eight eyes, which she relies on to track her fast-moving food.

She collects as many termites as she can,

greedily stashing them away to feed on later in the coolness of her burrow.

But the entrance is a tight fit, and this time, a clump of grass forms a wedge.

With her head stuck below the ground,

she's exposed and vulnerable to attack from the meerkat clan.

With difficulty, she squeezes in.

Eventually, she make it.

But the termites are not out of danger yet.

The most vicious of termite killers has found the entrance to their nest.

[suspenseful music playing]

The giant Matabele ants attack.

They bite the termites

and the sting paralyses them.

Systematically, the ants enter the termite hole and pull out body after body.

The dead and paralyzed termites are taken to the ants' nest to be eaten by the colony.

As the execution of thousands of termites continues,

slow-moving bull elephants follow invisible roads towards a mystery source.

[dramatic music playing]

They have struck out from the Boteti and are heading east, into the dry Makgadikgadi.

No one knows how they navigate,

but they head for far-off water points

in an ancient map network edged into their heritage.

When the bulls find a baobab, they take advantage of the shade provided by the huge trunks.

These tree are like beacons in the desert, and the elephants gravitate to them.

The elephants stay here through the hottest hours of the day,

when temperatures can easily reach 45 degrees Celsius.

These large, dark animals have no sweat glands

and they overheat very quickly.

Flapping their ears is the most efficient way of lowering body heat.

The breeze that is generated

cools the blood flowing in thousands of capillaries near the surface of the skin.

They will mobilize when the temperature drops.

But ahead of them lie miles of endless dry scrubland.

[ominous music playing]

Some don't make it.

Heat exhaustion affects an elephant radically.

These bulls need to time their journey just right.

[flies buzzing]

[thunder rumbling]

Out on the distant plains

the summer rains have finally arrived.

But a 100 miles away at the Boteti,

the skies are still clear.

[zebras yipping]

Yet the smell of rain is in the air.

An escape route from the Boteti hell has been opened,

and the zebra jump on it immediately.

For the pregnant mare,

this is one last gauntlet to run before a little nourishment becomes available.

[upbeat music playing]

She'll eventually have to return to the Boteti,

but for now, it's not worth thinking about.

During this trek, the animals hardly drink, rest or feed.

But at least there's hope at the other end.

Twenty-five thousand animals make the journey

in the second largest zebra migration in the world.

Exhausted, they arrive at their summer pastures in a spray of welcome rain.

For the next few months they'll have an unlimited supply of food and water.

[wildebeest grunting]

The bull elephants that struck out earlier, are ahead of the zebra,

and they have found one of the pools en route to the plains.

Their large shapes are a beacon to the thirsty herds.

But the elephants are possessive.

Perhaps they remember the previous confrontations over the Boteti water.

The zebra have no choice but to give way.

[instrumental music playing]

On the plains of the Makgadikgadi

there are no running streams or natural springs of underground water.

When the rains stop at the end of summer, the pools will dry up.

The bulls take their time.

But before they finish, more travelers arrive.

The zebras have to wait a little longer.

[birds chirping]

Once again the smell of water makes the weary elephants quicken their step.

The bulls give way.

The new arrivals are breeding herds of elephants with young.

They come from the distant Okavango Delta.

They wouldn't be here if not for the recent rain.

[crickets chirping]

[upbeat music playing]

All the zebra herds have now reached the grassy plains.

They can settle in here for a few months and regain their strength.

For the expecting mother,

the new grass is like a gift from the gods.

And finally she gives birth.

The rich pasture is crucial for the mother's milk,

and her new arrival spends most of the time suckling.

For the first few days of its life, the mother keeps it away from the herd

to imprint her unique smell and stripe pattern.

[zebra foal cries]

The little one is well developed at birth and is following its mother within an hour.

By three months, it will start to drink water and eat grass.

[zebra yipping]

Intruders aren't tolerated.

The foal's mother chases off any lost foals.

She needs to watch her new charge closely.

[foal braying]

Being lost here isn't wise.

[zebra yipping in the distance]

[ominous music playing]

[zebra yipping, braying]

The lions have been waiting patiently for the herds to arrive.

The mother has kept her foal safe.

The pride join the hunter and they finish the meal quickly.

[lion grunts]

A small foal doesn't take long.

[instrumental music playing]

As the weeks pass on the Makgadikgadi plains,

the foal follows her mother everywhere, moving with the herd from grass to water.

[upbeat music playing]

Life is much easier for the jackals now too.

But this water is only temporary.

The jackals know they have to make the most of summer.

Shadowing the lions is their number one priority.

Meanwhile, the foal's mother has carelessly dropped her guard.

[dramatic music playing]

[jackal yelps]

The jackals are hot on the lion's heels.

The lionesses have gone to fetch the cubs, while the male secures the kill.

For the scavengers, now is the time to strike.

The vultures' plan is to intimidate the predator.

[lion growls]

But this ploy doesn't work on the big male lion.

He has his hands full keeping control of the kill.

[lion growls]

The jackals are always waiting for a gap.

But facing the lion isn't an option.

[birds calling]

[lion growls]

Eventually, he sneaks a piece...

just before the lionesses reappear.

They'd left their two-month-old cubs in the den during the hunt,

and now they lead them back to the kill.

[instrumental music playing]

One of the lionesses tests the father's mood

before allowing the cubs near.

[lion growls]

A swipe from his powerful paw could cause a serious injury.

But he seems willing to share his meal,

and he allows the family to approach.

The cubs aren't so sure.

For the zebra foal

the tragic death of its mother is a huge loss,

but for the lion family, it's a windfall.

This carcass will keep them fed for a week.

[lion growls]

When the cubs have tried a little meat, they revert to playing.

For the lions it's been a successful day.

[lion cub mews]

The ever-patient scavengers finally get their turn.

And the jackal, once again, steals from the vultures.

[lions growl softly in the distance]

[instrumental music playing]

If the zebra foal doesn't stay with the herd, she'll never make it.

Keeping up is her only hope.

[instrumental music playing]

[jackal howls]

The jackal also has a family on the plains.

[jackal howls]

[jackals howling]

Jackals pair for life, and they have pups every summer.

[jackal howls]

By the time the rains bring an abundance of insects and food,

the pups are old enough to catch their own.

[jackal howls]

Although they still need to learn which of the little critters are good to eat,

and which bite.

[jackal yelps]

Soon, the pups will start to follow their parents on scavenging outings.

But that will be in another month or so.

For now, they stay close to their den,

groomed and cared for by their attentive mother.

[crickets chirping]

[instrumental music playing]

For the remainder or summer,

the cycle of life unfolds on the green plains of the Makgadikgadi.

Endless days of grazing nourish the herds.

Stallions compete for the favor of the females.

And the lone foal is carried along by the herd, gaining strength.

But the rains eventually cease,

and the clouds disappear.

The grasses dry, leaving bare, sandy patches.

Without rain to replenish the pools, they start to dry.

The time has come for the zebras to leave the plains.

Staying here is not an option.

Soon there'll be nothing for them to eat or drink.

[zebras yipping]

Their 80-mile return journey to the pools in the dry Boteti river, will be a grueling trip.

[instrumental music playing]

For the lone foal, this will be the most difficult journey in its life.

Some foals are smaller, but at least they still have their mothers close.

But others already lag behind.

In baking temperatures,

the zebras reach the edge of the drying summer pastures.

[zebra yipping]

The ever-present vultures track the herds,

waiting for the weak to stumble.

[vultures screeching]

Within a couple of hours, a dead animal is almost stripped clean.

The lapped-faced vultures do their job.

Their powerful beaks open up the hide and cut through the tendons,

allowing the rest of the scavengers access to the innards.

[jackal barks]

[vultures screeching]

The zebras can't slow their pace,

the more they linger, the faster they dehydrate.

[zebra yipping]

Their survival now depends on how quickly they can reach the Boteti river,

and whether there is still water there.

Halfway through their journey, they get a lucky break,

a last pool of rain water.

But they're edgy as they drink.

Lions often wait around water.

[zebras yipping and snorting]

They need to drink as quickly as possible

and be on their way again.

[zebras yipping]

The dry scrubland lies ahead of them.

[ominous music playing]

It's the last obstacle before the Boteti river,

but an old stallion is dropping behind.

The harsh conditions separate the strong from the weak.

[zebra moans softly]

[vultures cackling]

Eventually,

the first herd of tired and traumatized zebras

crest the bank of the Boteti.

They walk into the river bed where there should be flowing water.

But all they see are the desperate hippo.

The foal has made the journey.

It's endured the most difficult survival test.

And the youngest ones, born late in summer, are also lucky to be alive.

But for the twentieth consecutive year, the river is dry.

But there's something these animals don't know.

[instrumental music playing]

[water trickling]

A little further upstream, a trickle is dribbling across the hot sand.

It brings new visitors.

Tiny fish ride the head of the flood.

Slowly, the stream gathers momentum.

And within hours, water is charging down the upper reaches of the Boteti.

[birds chirping]

The flood has travelled 700 miles from the north.

An usual amount of rain has fallen over the mountains of neighboring Angola.

The waters fill the Okavango Delta to the highest recorded flood level in 30 years.

For months, this water has crossed the shallow gradient of the desert,

spilling out of the delta, and moving steadily south.

And as the zebra and elephant arrive back in the dry Boteti,

these far-off rains will soon be delivering salvation.

For the first time in 20 years,

the Boteti starts to flow.

Suddenly, the crocodiles that ate nothing more than little parcels of feathers,

have something new to feast on.

[toads croaking]

The olive toads that hibernate through the drought,

wake up.

They never know how long the floods will last,

so they waste no time looking for a mate.

[toad croaking]

Competition is fierce,

and the highly desirable females are mobbed.

[toad croaking]

The overenthusiastic males sometimes drown the female.

Individuals that survive the orgy,

lay as many as 25 000 fertilized eggs in long strings

in the calm shallows of the river.

The eggs will hatch within 24 hours.

[birds chirping]

Soon the quiet backwaters of the Boteti,

writhe with newly-hatched tadpoles.

They stay in the water and feed on algae.

An elephant footprint can hold thousands.

The first froglets are already emerging.

Although hundreds of thousands make the metamorphoses,

thousands are eaten,

and very few survive to become adults.

The following day, water reaches the last Boteti pools,

filling the hippos' stagnant mud wallow to bursting point.

[hippos grunting]

This year, if the cows give birth, the dominant bull will allow the youngsters to live.

But despite the rush of water,

the surrounding landscape is still dry and dusty.

[ominous music playing]

The remaining zebra herds arrive at the river,

but what they find, surprises them.

The oldest ones remember the last time the Boteti was in flood.

But for the majority, the flowing river is a new experience.

They approach it cautiously,

but soon drop all inhibitions.

[instrumental music playing]

[bird calling]

For the first time in its life,

the foal can immerse itself in the river.

[zebra yipping]

The elephants arrive too.

[elephant trumpets]

They have seen the floods before.

They remember them well.

[zebras yipping]

[elephant trumpets]

The tussle for water still lives in these creatures' minds.

But now there is no real need for confrontation.

[zebra yipping]

For the elephants, it's a time for celebration.

For the first time in decades, they can swim.

With so much water around, there is plenty of space for everyone.

[thunder rumbling]

And by the end of the winter,

rains come to the dusty Boteti.

The area greens,

[birds calling]

and the zebra will now have grazing here too.

The river swells with the promise of fresh water that will stay for the year.

[thunder rumbling]

Eventually, the summer rains will draw many of the animals away from the Boteti again,

but this time, the migration will be much easier.

And they will a lush paradise to come back to.

But for now, the tough drought of the past 20 years

is already a distant memory.

And the Boteti survivors revel in their new surroundings,

[elephant trumpets]

blessed by the miracle

of the returning river.

[hippo grunts]

[African music playing]