Original subtitles

Tropical rainforests are one of the oldest

continuous Iiving entities on earth

older than many of the stars.

This rainforest has been evolving

for 1 30-miIlion years.

Season after season, century on century,

the forest has been shaping the destiny

of the creatures it shelters,

as they in turn have shaped their forest.

This story of an Asian rainforest

is the story of the remarkable relationship

between the forest and it's plants and animals.

The dawn chorus of primates is a truly Asian sound,

for Asia has the greatest diversity of primates anywhere on earth.

The new day begins like the countless miIIions

that have dawned before.

The forest and the myriad creatures within it,

stir to the coming of light and warmth.

The rainforest in aII its compIexity

can be seen as a singIe living organism.

lt consumes rain and warmth' and exhaIes oxygen.

The canopy of the rainforest is like the outer skin.

It receives the most sunlight'

it's the most exposed to wind and rain

and it protects the forest beneath.

Rainforests are incredibly rich.

AIthough they cover only 5% of the earth's surface,

they're home to at least haIf of all the species of plants

and animaIs on earth.

High in the tree tops, the animals wake hungry.

The Thomas's leaf monkeys spring across the canopy

Iooking for breakfast.

Asia's great red ape - the Orangutan

live in the stronger branches midway down the trees.

They too are setting off for breakfast.

Siamang herald the morning with a duet of Iove.

The calIs between male and female

are also a procIamation of their territory.

A most fascinating example of the relationship

between the forest and it's creatures'

is that between a group of great red apes

and the remote corner

of the Sumatran rainferest where they live.

They've been studied for more than 5 years΄

Their behaviour offers a gIimpse into the past of Orangutan,

and a hope for their future.

Each has been given a name.

andi is a 9 year old female.

She's getting used to Iiving on her own

after her mother eased her aside to make way

for her new baby sister.

Her mother Arni will be devoted to her new infant for 8 ears

just as she was to andi.

Arno, the father of andi, is the dominant maIe

of this part of the ferest,

and probabIy the father

of almost all the youngsters in his territory.

Orang-hutan means "people of the forest".

The Malay have a Iegend that the Orangutan

was so inteIligent that it never learnt to speak,

fearing that if it did' it would be put out to work.

Arno has the demeanour of a gentle giant.

Yet he would have feught fiercely to become the dominant male.

He Ieads a soIitary life, leaving the upbringing

of his chiIdren entirely to the females.

The simplest reIationship

that the Orangutan have with the forest

is also the most naturaI.

Gravity ensures that sooner or Iater,

everything they eat or touch falIs to the ground.

The ferest fIoor is where everything ends up:

dead animaIs, leaves' seeds, and droppings.

Fresh Orangutan dung seems to have a life of its own.

Attracted by the smell'

dung beetIes soon begin the recycling process.

The beetles carve up the dung and pat it into balIs

which are easy to roll away and bury.

They will Iay their eggs in the dung.

Eventually it will all be recycled

and the nutrients reabsorbed into the trees.

The forest fIoor is the gut of the forest.

The ferest digests its waste in less than an hour.

The leaf Iitter takes longer to decompose.

But eventually the nutrients are Ieached out of the leaves

and into the soils.

Ants are the most common insects of the rainforest

and they too play an important part

in the recycIing of rainforest nutrients.

These ants are dismembering a hornet to take back to their nest.

Ants and their termite cousins are a vital part

of the forest's digestive system.

Termites break down rotting wood

and carry it aIong well-worn forest trails to their nests΄

Along these routes'

they and their precious food are guarded by soIdiers.

AIthough they're tiny, insects are forest heavyweights.

They make up a third of the mass

of alI the animals in the rainforest.

For creatures higher up the food chain,

insects are a valuable source of protein.

Above the termite trail' a spider lies in wait,

snarin an unsusectin victim.

As they approach the nest with their load,

the termite trail becomes a Iivin conveor belt.

and despite appearances'

there is also order in the rainforest canopy.

The Ieaf-eating monkeys are foIIowing weIl-jumped pathways.

It's mid morning

and they criss cross their territories searching for food.

They catapult into space

with the confidence that comes from countIess generations

of living with the forest.

The Leaf-eating monkeys live in smaII groups of females

with a dominant male.

The size of his group is determined by the forest:

since the male likes to be abIe to keep an eye on them all,

the thicker the ferest, the smalIer the group.

All the members of his harem are equal.

There's no top fomale with first cIaim to the feeding area.

The Leaf-eating monkeys are free-loaders.

They give little back to the forest.

By taking fresh leaves,

they rob trees of their means of absorbing light and energy.

By destroying seeds,

they make it harder for trees to reproduce.

The trees toIerate these charming bandits.

But they fight back b introducin toxins

into the maturing leaves which spoil the taste.

Below the Ieaf-monkeys' in the mid branches,

Orangutan play a much more constructive roIe.

They mostly eat fruit.

because they are big, they need to be big eaters.

Fruiting trees are scattered throughout the forest.

Each animal has a 3- dimensional map in its brain

and knows where and when fruit will ripen

and how to get there.

As they move from one tree to the next,

eating as they go,

the Orangutan disperse the seeds of many species

a major role in the growth of the forest.

Orangutan range throughout the Sumatran hill forests,

but when fruit is pIentiful

they gather in their greatest numbers

in the Iow-lying swamp forest.

It's here that their relationships with each other

and the forest are being studied.

This male is nearing his prime.

Perhaps one day he will chaIlenge Arno

to be the dominant male.

But until he's sure he'll win, he stays well clear.

The forest has adapted to the size of these Orangutan

by producing many of their favourite fruits close to the trunk

where they're easily reached.

This maIe will return to this tree again and again

throughout the 50 or so years of his Iife,

one of the longest reIationships anywhere

between a tree and an animal.

The closest bond in the animal worid

is between a female Orangutan

and her infant.

This intensive mothering is the bond

that shapes the infant's life.

The mother is the source of food, shelter, transport

and the vitaI lessons for lifo.

She wiIl pass on all her knowledge of the forest and its fruitings.

Without which the infant couId not survive.

Part of the knowledge that Arni passed on to andi

was a way of using a tool to soIve a problem

behaviour that has been seen in the wild

only in this swamp forest.

One of the delicacies the Orangutan enjoy

are the seeds of the chamangan fruit.

As the fruit ripens'

the sheIIs split to reveal the seeds inside.

The problem for the Orangutan is the sharp hairs'

painful to touch' which protect the seeds.

Sometime in the past

one of them worked out

how to overcome the plant's defences.

Now andi has learnt to put the stick in her mouth

and use it to pry out the seeds.

The seeds either drop into her mouth or her hands.

The hairs fIutter to the ground.

Millions of years ago

our own ancestors first learned to use tools.

We don't know whether Orangutan Iearnt to do this only recentIy

or whether they've been doing it for centuries or miIIennia΄

What is certain

is that this behaviour has never been recorded

in any other group of Orangutan.

We once beIieved that our ability to use tools

separated us from the rest of the animal kingdom.

Perhaps andi is showing us

that Orangutan are even cIoser to us than we imagined.

With the two prerequisites for life:

sunshine and water abundant,

rainforests are one of the most favourabIe environments

fer plant growth on earth.

A square kilometer of rainforest

can have as many as 1 0'000 species

this is the ReaIm of the Red Ape.

ln the tropics there are two seasons, the wet and the dry.

Plants flower and fruit according to their own cycle.

The Rainforests at the north of Sumatran Iie cIose to the Equator

and receive aImost equaIized daylight and darkness΄

Yet for each individual tree

the amount of light it receives depends on its pIace in the forest.

The forest floor sees sunlight only at midday,

the mid branches receives about 8 hours,

the tree tops see light from sunrise to sunset.

During the day'

the leaves of the canopy are in almost constant sunIight.

The mid branches however, receive onIy fiItered Iight.

and at midday, when the sun is directly above the trees,

the forest fIoor receives only dappIed Iight

as passing sun specks.

It is this limited suppIy of Iight that restricts growth

on the forest floor.

This pattern of light

is interrupted onIy when a tree dies and falls,

creating a gap in the canopy which there is a race to fill.

Creepers wind their way round other plants

to haul themselves upwards'

whiIe saplings stretch towards the light.

Very soon the canopy is complete.

The race is over, the winner takes all

and the losers adjust to their rations of sunlight.

Crucial to the relationship between the animals

and the forest

is their underst anding of the seasonal cycles

of different species.

The animals always know

where and when their favourite Ieaves

and fruits are ripening.

While some trees are in spring-like abundance'

others will be shedding leaves, as if it's autumn.

Some seeds parachute away to germinate on the ground,

others are carried on water.

The seeds may germinate many kilometres from the parent tree.

So' although the trees can't move, they can travel.

In the dry season,

the ferest produces fewer leaves and seeds,

so there's less food for everyone.

If there's a stream in their territory,

the Ieaf-eating monkeys supplement their diet with algae.

They come down from the trees Iike travellers to an oasis.

There's enough aIgae in the stream for severaI groups

from overIapping territories to share.

WhiIe they're up in their element, the canopy,

the monkeys are safe from almost all predators΄

But on the ground, they are vuInerabIe.

FemaIes with older infants leave them in the trees.

For as long as the Ieaf monkeys remain on the river,

the male keeps a nervous watch.

There are still some Sumatran tigers on the prowl.

Unaware there's a tiger about,

femaIes with infants that are too young to Ieave in the trees,

bring them down with them to the water.

Sometimes'

even the most caring mothers become forgetful.

However high his hopes,

the tiger's chances of a meal are remote.

As soon as the he hears the leaf-monkeys' alarm call,

he moves on.

He has to kiIl only 2 or 3 times a week,

and he knows when the monkeys are beyond reach.

The mouse deer is the worid's smaIIest hoofed animal.

It has no protection against the tiger except its aIertness.

Its huge eyes are placed where it can best detect any movement'

its ears are alert to any dangerous sound.

Despite its name,

the mouse deer is a species

somewhere between a pig and a deer.

Indeed,

the Malays have a Iegend that the mouse deer

is a forest spirit so cIever that it can outwit the tiger΄

High in the trees,

Orangutan are safe from most predators.

The biggest threat to this mother and her baby

may be the unwanted attentions of a maIe.

If he can get cIose enough, he will stop at nothing to mate.

and both mother and child couId be hurt.

To keep out of harm's way,

she moves to the thinner branches

where she knows he can't folIow.

But the would-be suitor was probably more at risk.

For in this part of the forest Arno remains dominant.

His presence is usualIy enough to keep other males at bay.

There is still a few eIephants in the Asian Rainforest.

By knocking down trees they help disperse seeds

and let in light.

But the forest infIuences them too.

The dense vegetation forces them to Iead more soIitary lives

than their cousins in Africa.

Even for elephants' the forest has its no go areas.

Some plants grow spines

which discourage even the largest animals.

Other plants enlist the services of insects in their defence.

These ants help protect the wiId raspberry

by deterring leaf-eating caterpiIlars.

Once they've driven the caterpillar off,

the ants claim their reward.

They milk a colony of aphids

for the sugary secretion they produce

from the sap of the raspberry.

Perhaps the most cruciaI reIationship of aII

is the role insects play in enabling the forest to reproduce΄

By offering irresistibIe nectar

these pIants entice ants to travel from flower to flower,

transforring the vital pollen.

Throughout the forest, the same system of service

and reward appIies.

Different plants flower at different times,

attracting different pollinators.

This one flower attracts sweat bees.

Pollination is the service the sweat bees provide.

Their reward is nectar, which they carry back to their nest

From the nectar'

the bees make honey as food for their larvae.

Even the most singular of species

follows the rules of service and reward.

This bud wiII become the rainforest's largest

and perhaps rarest fIower...

the rafflesia' which has no Ieaves or stem,

and draws its sustenance from the vine on which it lives.

The Rafflesia takes 4 or 5 years to flower

and is polIinated mainly by flies which it attracts

with the stench of rotting meat

It can reproduce easiIy

only if another rafflesia is fIowering within a fly's range.

Once the flies have done their work the RaffIesia dies.

Like everything else on the forest floor,

it is absorbed and recycled.

Butterflies emerge to reproduce.

Most butterfly species seek nectar from flowering plants.

As they feed, transferring pollen from flower to flower'

they make it possible for the plants to reproduce.

Once they find a mate and lay their eggs,

their work is done.

At midday the forest slows.

High in the trees, the leaf-monkeys pause

after a morning of intensive feeding.

They descend to a shady siesta spot to rest

and fully digest the mornings leaves.

The young wilI play.

With no hint of danger, the maIe can afferd a catnap.

The females become so drowsy that one mother dozes.

While the Thomas's leaf monkeys come down

into the mid branches for their siesta,

the Siamang take their time out at the top.

Playing serves a purpose for the young apes.

This is how they learn how far they can leap,

what weight a branch can carry, and what risks they can take΄

The learning never ends.

Beneath the Siamang' in the mid branches,

the Orangutan also pause.

Female Orangutan may have no more than three young in their lifetime,

so each one is precious.

Between this mother and her infant

there is something almost human.

In the dry season, the rains are Iess frequent,

and usually arrive in the afternoon.

ReguIar downpours are essentiaI for life in the forest.

The Orangutan find shelter where they can.

The canopy of the forest breaks the force of the rain,

and stops it from washing the topsoiI away΄

Many trees have leaves which channeI the rain

to where it's needed most

their roots.

Some pIants have an umbreIla to keep the rain out.

After only a fow hours the sun returns,

the heat buiIds up,

and water is sucked up by the roots,

and then flows up through the trunk into the leaves,

where it released back into the atmosphere.

Beneath the canopy, the humidity is high

and reIatively constant.

As a result' the forest floor is constantly moist

and many creatures have evolved in this damp environment.

Leeches depend on moisture,

and Asia is one of the few places

where they've adapted to live outside pools of water

or sIowIy-running streams.

Leeches are hermaphrodites: each is both maIe and female.

Mating invoIves both partners passing sperm

to fertilise each other's eggs.

The mating begins when they attach their suckers to each other,

and sway their bodies until they can establish cIoser contact.

Once the pair have aligned their sexual organs, they mate.

Each of them can now go on its way with its own fertilised eggs.

The adults can survive without water for only a few days.

But even if they perish, their eggs wilI remain

as a survival capsule for their species untiI the rains come again.

Eons of rain have faIlen on the forest,

much of the goodness has been washed away.

Some plants have adapted to the poor soils

by becoming predators.

Asia is home to the worid's greatest diversity

of carnivorous pitcher plants'

which entice their victims by exuding the sweet smell of nectar.

This is service and reward with a twist.

Insects are drawn to the trap by the promise of a reward.

But they slip and then die.

lnstead it is the plant that gets the reward -

energy.

AImost everything

that faIIs inside the pitcher plant drowns and is digested.

Yet even in a graveyard there is life.

Somehow, mosquito Iarvae thrive in the pitcher's digestive juices.

The pitcher plant is a gut within the gut of the forest.

lts deep in a remote corner of Northern Sumatra,

that the unique reIationship between the great red ape

and the rainforest is being studied.

In one of the few remaining patches of lowl and swamp forest

Orangutan gather in greater numbers than have ever been seen elsewhere.

They reveal secrets of how their ancestors may have Iived

before their habitat was lost.

They come because the lowl and swamp forest is richer.

Trees here produce more fruit than those in the hiIl forests.

They also benefit from the constant wetness

of the ferest fIoor.

Many of the insects that would normaIly Iive in nests

in the ground

make their homes instead in the trees,

where they become an easy source of extra protein for the Orangutan.

Asia's largest primates congregate in the swamp forest

for as Iong as the fruiting season Iasts.

This is where andi grew up.

She learned the forest from her mother.

She and her companions know where food is and how to get it.

andi remembers the sweat bee's nest.

and she aIso remembers the Iessons she learnt from her mother.

She knows how to get the honey that is beyond the reach

of her searching finger.

As she did with the chamangan in this same forest,

she uses a tool.

It's just a twig, broken and shaped to length.

But by using this simple tool

andi and a few of her relatives

are in a fellowship of their own.

This is behaviour they have Iearnt and remembered.

Arni's new sister wiII Iearn the same lessons.

It may be the birth of a new Orangutan culture,

Why Orangutan use tools here and possibIy nowhere else

remains something of a mystery.

When she's finished the honey,

andi will use her knowledge of the forest

to traveI to another tree.

The sweat bees return instinctively to repair their nest.

Orangutan choose different food at different times.

After she's had enough honey'

andi aIways nibbIes a leaf perhaps to balance her diet΄

When the time comes for andi

to pass on what she's been taught, the learning wilI be easier

and the knowledge may spread faster

because of the different way these Orangutan Iive.

We used to think that they were aImost aIways solitary animals,

with the only bond between a mother and child,

or when small groups gathered briefly around a fruiting fig tree.

That may be true eIsewhere' but not in this part

of northern Sumatra.

They return to the swamp forest season after season, to sociaIise

and Iearn with the same individuaIs.

AduIts and juveniles recognise each other

and choose their companions carefuIly.

If they were human, we wouId call them friends.

Young Orangutan here in the IowIands

have the chance to play with each other far more frequently

than their cousins in the hill-forests.

But they may not be able to pass on

what they've learned here to new generations.

Already hunting and the destruction of their habitat

have made Orangutan an endangered species.

AIthough they may be sociable during the day'

at night the Orangutan keep to themselves.

Adults nest alone.

At the end of each day,

fresh branches furnish a new nest.

Each night a new nest'

each night' a new tree.

But this infant, its mother is its worid.

Even as he makes his nest

Arno shapes the forest that stiII shapes him.

As he settles for the night he gives his long call

proclaiming his territory and his being.

Arno's long calI declares the importance of his species

and his culture.

It's a call to those who have power

to save his realm in this corner

of the Sumatran rainforest'

and with it, Asia's great red ape

and their unique way of life.