Original subtitles

NARRATOR: One island dominates Southeast Asia.

Borneo...

..the third largest in the world.

Here, evolution is in overdrive...

..an explosion of life.

But the diversity of this island is threatened...

..by the actions of humans.

From the Arctic... (GROWLS)

(CHUFFING)

..to the tropics... (TRUMPETS)

..islands are wild laboratories...

..where unique rules apply... (SQUAWKS)

..and nature puts life...

(HISSES) (CHATTERS)

..to the ultimate test.

(GROWLS)

Although Borneo seems to be blanketed in greenery,

it's an island of many worlds.

Isolated limestone outcrops...

..ancient rainforests...

..biodiverse mountains...

..and mighty rivers.

(BIRDS CALLING)

(CHATTERING)

The Kinabatangan...

..an artery cutting through Borneo's dense forests.

Tiny giants patrol its banks...

..in a never-ending quest for food.

(ELEPHANT HUFFS)

(RUMBLING)

The smallest pachyderm on Earth...

..the Bornean pygmy elephant.

(TRUMPETING SOFTLY)

They must face the river's powerful waters

to find new feeding grounds.

They can't get enough nutrition from the island's vegetation,

so they've shrunk to adapt... (TRUMPETS)

..and are only two-thirds the size of their mainland cousins.

(HUFFS)

This little fellow is getting to grips with life on the move...

..along the river highways.

(TRUMPETS)

He'll walk for up to five kilometres a day...

..because when the herd has eaten everything in one area...

(TRUMPETS, HUFFS)

..they have to move on.

It's a tiring regime for short legs.

The water provides welcome relief from the island's stifling heat.

(HUFFS)

But try to cross it...

and the river will reveal its full power.

(TRUMPETS)

And that's exactly what this bull is about to do...

..to find fresh food.

The river is wide... and fast-flowing.

Even weighing in at four and a half tonnes,

he struggles with its currents.

(TRUMPETS)

And the river's steep banks are yet another barrier.

(HUFFS)

Life can be tough for tiny giants in Borneo...

especially when they enter enemy territory.

Borneo wasn't always an island.

It once formed the highlands of a Southeast Asian landmass.

But as sea levels rose at the end of the last Ice Age...

..it was cut off...

along with its animals...

and its vast, ancient rainforests.

The forest's canopy soars 100 metres high...

..the tallest tropical rainforest in the world.

It rewards those who brave its heights with fruit.

But you need to learn which are safe to eat,

and which might be poisonous...

..especially when you have a baby to raise.

This orangutan mother must pass on the art

of how to survive up here.

With so much to learn,

she'll stick to the small patch of forest she grew up in

and keep her baby by her side,

nursing her for up to eight years...

..longer than any other mammal.

(CHATTERING SOFTLY)

Finding edible fruit is a never-ending task,

especially as most trees here don't fruit every year.

So throughout this time, baby keeps suckling milk,

a vital last resort when times are tough.

Borneo supports around 15,000 plant species...

..but many are poisonous.

Baby must memorise which ones are safe to eat.

(SQUEALS QUIETLY)

Luckily, she's a keen learner.

She'll need to be.

There are more challenges from the high canopy ahead.

(CHATTERING SOFTLY)

Deprived of light by the canopy,

Borneo's forest floor can be an unwelcoming place...

(BEAR SNORTS)

..unless it's your own personal playground.

This is Luna...

(SNIFFING)

..a sun bear...

..the smallest bears in the world.

Just like Borneo's elephants,

Luna has adapted to a lack of food...

by evolving a smaller body.

And the lighter you are, the higher you can climb.

(GRUNTS) At least, that's the theory.

Sun bears are vulnerable to extinction...

..victims of habitat loss.

Poachers hunt them for their body parts

and take cubs to sell illegally as exotic pets.

Luna was separated from her mother at birth.

And at only six months old...

she still has a lot to learn.

Luckily, she has a helping hand.

Luna lives in a refuge for sun bears.

The bears are protected here

until they are ready to be rehabilitated into the wild.

A ranger takes her out daily...

so she can develop her instincts to forage and climb.

Once she's mastered these skills...

..she can join the other sun bears...

..up in the high canopy.

(BIRDS CHIRPING)

Borneo's rainforests are challenging places to live.

Every creature must find its own niche to survive here.

But because they rely on these unique habitats,

they are vulnerable to change.

It's well known that the island's rainforest is shrinking.

In just 40 years, Borneo has lost nearly a third of its forest cover

to fire, logging, and oil palm plantations...

..twice the rate of the rest of the world.

Today, only small pockets remain for animals to live in.

(ELEPHANT RUMBLES)

With so little left,

the elephants are forced to leave the safety of the rainforest.

The herd has been walking non-stop for days...

(RUMBLING)

..and the baby is getting tired.

They have little time for rest.

Nursing him depletes his mother's energy.

And she's not the only one who's weary.

There are elderly here, too.

(HUFFS)

But they must keep moving...

..to find enough food.

(TRUMPETS)

85% of the world's palm oil comes from this island.

Found in everything from bread to shampoo,

it's the most widely used, edible oil in the world.

Plantations have changed the face of the island,

fragmenting the landscape.

(RUMBLING)

There's no way elephants can avoid them.

Noise cannons, snares,

and electric fences are used to keep them out.

(TRUMPETS, HUFFS)

(RUMBLING)

But the lure of food is too strong...

..so they break in and feed on the palms.

(TRUMPETS)

The baby is at risk here.

If his herd is startled...

he could get trampled or abandoned.

And he's too young to make it on his own.

(RUMBLING)

The elephants aren't welcome here.

Where pristine habitats remain...

Borneo rivals the Amazon as a treasure trove of biodiversity.

And the secret to that natural profusion

lies high up in its mountain range.

Here, millions of years ago...

(RUMBLING)

..tectonic forces thrust up a giant ball of granite through its surface...

..Mount Kinabalu.

The tallest mountain between the Himalayas and New Guinea.

At over 4,000 metres...

..it's almost twice the height of its neighbours and...

with ongoing collisions under its surface...

still rising.

Kinabalu creates its own weather systems.

Different altitudes, soils, and climates...

..create scores of unique habitats...

(BIRDS CHIRPING)

..from tropical lowland rainforests...

..to freezing sub-alpine meadows...

and everything in between.

Nature has adapted to every niche...

with an explosion of plant life...

nearly three times the density of species in Europe...

crammed onto a single mountain.

Soils on its granite slopes are high in metals...

..and low in nutrients.

Pitcher plants can't extract useful minerals from them.

So one giant has evolved its own way to get what it needs.

Nepenthes rajah...

the largest carnivorous plant in the world.

It lures insects with its sweet scent to its pitcher...

..an open-air stomach, lined with a slippery rim.

Two and a half litres of digestive fluids get to work straight away...

..drowning...

dissolving...

and releasing minerals from its prey.

By isolating plants like the rajah,

this mountain forces them to specialise.

A perfect laboratory for evolution.

Mount Kinabalu isn't the only place where the island's geology

has fuelled a host of strange adaptations.

In some of Borneo's least explored areas,

a battle against the elements has carved razor-sharp shards.

Limestone outcrops of ancient seabed...

thrust high above the surface...

whittled away over time by rain.

Entire species of limestone snails...

live their lives stranded on a single rock...

(SQUELCHING)

..like tiny islands within an island.

The outcrops are packed with the calcium

that the snails need to build their shells.

The Fairy Cave Gecko.

Its long toes and curved claws...

can cling perfectly to the rough limestone walls.

These rocks are home to the ultimate specialists...

many never captured before on film...

..like this yet-to-be-named species of jumping spider...

..some of the smartest spiders in the world.

She uses stealth...

and deception to hunt her favourite prey...

..other spiders.

These rocks don't provide much cover,

so she's evolved to hide in plain sight.

She strums on her victim's web...

..to draw him into the open.

Her 360-degree motion sensors...

..mean she always detects her prey...

..before they see her coming.

Blending into her surroundings,

she settles in for a feast...

..safe from the eyes of potential predators

..on her landlocked limestone island.

In some corners of Borneo,

isolation has sent evolution off on a strange path.

Tiny islands fringe its east coast,

atolls wrapped in living coral,

in deep, nutrient-rich waters -

some of the most diverse marine habitats in the world.

But one island hides its submarine world on the inside...

..Kakaban.

Twelve thousand years ago,

a submerged volcanic crater was lifted up out of the water...

..trapping sea creatures in a marine lake...

separated from the sea by a thin strip of land.

It has created an extraordinary ecosystem inside.

The most unusual inhabitants here...

..are jellyfish.

Protected from large ocean predators outside,

they have become practically stingless.

But there's a catch.

They're cut off from their food supply, too.

So, these jellyfish live off light.

They take the energy they need from algae that live inside them.

Every day, they rise to the surface,

so the algae can soak in the sun's rays.

And in return, the algae release nutrients.

But this haven is not entirely safe.

An unexpected predator lurks at the bottom of the lake.

Anemones. They've kept their sting.

But it's a small price to pay...

..when solar-powered jellyfish...

..continue to thrive in their thousands...

..in this unique habitat.

(BIRDS TWITTERING)

Borneo's rainforest is unlike any other.

More than twice as old as the Amazon,

a battle for sunlight over 130 million years

has produced the world's tallest tropical trees.

Dipterocarps dominate here.

Anyone trying to make a life atop these ancient giants

must learn the rules of living at extreme heights.

Orangutans have no problem navigating the high branches.

But take a nap up here, even they could risk a fall.

Every mother must show her baby how to build a secure nest.

(CHATTERING SOFTLY)

She watches her mum closely.

(BRANCH SNAPS)

She's a good mimic.

Each day, she builds survival skills...

..and today, her own first nest.

Or is it a trampoline?

Somebody isn't taking this learning experience very seriously.

(SQUEALING)

Single parents seldom get much rest.

Mum just wants five minutes' peace.

(CHATTERS SOFTLY)

(SQUEALS)

Maybe she'll settle in Mum's nest for a little nap?

No such luck.

There's a point to all this play.

(SQUEALS)

With each swing, she's becoming more confident,

venturing further away from her mother.

It's a risky game...

but an important one. (SQUEAKS)

She needs to learn what kind of branches can carry her weight.

It's the only way she will ever be able

to navigate the island's high canopy.

(CHATTERS)

The rainforest's extraordinary diversity relies on its water cycle.

And when the heat rises,

there's nothing Borneo likes more than a good shower.

(THUNDER RUMBLING) Almost every afternoon...

like clockwork...

warmth and moisture build up from the forest floor

until clouds hang heavy over the island's canopy.

And finally...

..it rains... (BIRDS CHIRPING)

..quenching the forest...

..feeding the rivers...

(ELEPHANTS TRUMPET)

..and bringing relief from the heat.

(THUNDER CRACKING)

By storing and releasing its own water,

the island's rainforest plays a crucial role

in stabilising the climate.

When the rain stops,

it's the perfect time to start moving again.

(WHOOSHES)

A Draco lizard uses the canopy as a commuter route.

He glides to avoid dangers on the forest floor.

His wings mimic the colour of falling leaves...

to camouflage him from birds.

He's found some prime real estate.

It's the perfect vantage point...

..and even has a built-in food supply.

But there's competition.

Another Draco has its eye on his tree.

He waves a warning semaphore flag...

..a signal to the intruder to get off his turf...

..and keeps hold of his tiny territory.

Before industrial logging began in the seventies,

the residents of the high canopy

could cross the island without ever touching the ground...

..even the biggest tree-dweller in the world...

the male orangutan...

weighing up to 90 kilos.

(HUFFS)

This is impossible now.

More than half of his habitat has disappeared in the last 20 years.

And it's still going.

It's thought that one in four orangutans

will lose their homes in the next decade.

This won't only limit his ability to find enough food

to maintain his great size...

..but also his role in the regeneration of the forest.

Because, unwittingly, he helps grow new fruit trees.

(BIRD CHATTERS)

And in a forest that doesn't bear a lot of fruit,

that's incredibly important.

Often, when he eats...

he dislodges figs...

..and he also deposits seeds in his droppings.

Male orangutans roam over territories three times larger than the females',

so his role as gardener of the forest

is essential for the island's health.

It will be a while before he finds another fruiting tree in this forest.

So, he conserves energy...

..to make the figs go as far as possible.

Like the canopy,

Borneo's rivers provide a route across the island,

but they can also be a barrier.

(SQUAWKING)

Plantations squeeze pygmy elephants towards the riverbanks...

..while highways, bridges and villages cut them off either side.

The herd has run out of options on this side of the river.

(RUMBLES)

There's no choice but to cross it

and look for safe foraging on the other side.

The baby hasn't learned to swim yet...

..but the matriarch thinks it's time. (RUMBLES)

(TRUMPETS)

(TRUMPETS)

(TRUMPETS)

But baby panics and tries to turn back.

(TRUMPETS)

(BIRDS CHIRPING)

He's confused...

(TRUMPETS)

..but finds his way back to Mum.

(TRUMPETS)

And the herd gathers close...

..to guide him to the other side.

(HUFFING, RUMBLING)

(TRUMPETS)

The island rewards them.

A safe haven with plenty of food.

Finally, they have somewhere to rest for days.

Theirs is an ongoing struggle.

With only 1,500 Bornean elephants left...

..reconnecting them with other herds is crucial to their survival.

There are some signs of hope.

Sustainable plantations can become part of the island's habitat...

..if they retain patches of natural forest.

Some plantations are opening up wildlife corridors

that allow animals to pass through safely.

And a few corners of the island remain untouched by humans.

Inaccessible mangrove swamplands...

..the haunt of a mysterious primate...

found only on Borneo.

(MONKEY CHATTERING)

(MUNCHING)

Proboscis monkeys.

(CHATTERS)

They're old hands on this island

and have had longer to adapt to its ways.

Tall trees lift them out of reach of predators,

leeches and mosquitoes. (CHATTERS)

The youngest leaves are up here, too.

But even these are tough and toxic.

Only proboscis monkeys have evolved to stomach them.

His big nose makes this male irresistible to females...

..and acts as an amplifier...

so he can alert his harem to danger.

(MONKEYS CHATTERING)

Although they're the strongest swimming primate,

there are dangers in the island's rivers...

(CHATTERS)

..so they stick to the safety of their lofty branches.

Occasionally, the island will throw its inhabitants a lifeline.

Most of the trees in Borneo's rainforest produce fruit

just once every four to eleven years.

But there's one tree that fruits year-round...

the fig.

Islanders believe it carries spirits...

so it is never logged.

They call it "the tree that never sleeps."

A giant might start out as a tiny seedling from an orangutan's droppings.

It wraps itself around a tall host tree,

vine by vine,

and slowly starves it of nutrients and light.

And when a mature fig tree is in fruit...

(BIRDS CHIRP)(MONKEYS CHATTER) ..word gets around fast.

Primates appear one by one.

Gangs of macaques are first to arrive.

(HIGH-PITCHED WARBLING)

Rare Bornean gibbons swing in...

..to reach branches...

the others can't.

Then, there's the orangutans.

Mum knows this tree well,

but it's the first time the baby's seen it in fruit.

Now she can add it to her mental map of their little patch of forest...

..to memorise when and where scarce treasures can be found.

The big male arrives at last...

..to a tree perhaps planted unwittingly...

by one of his ancestors.

The whole forest relies on these figs...

..to get them through the hard times...

..just as the island relies on each of its extraordinary habitats...

..from its rivers to its rainforest...

..its peaks to its coast...

to support this incredible proliferation of life...

..found nowhere else on Earth.

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