Original subtitles

The sun... giver of light and life.

Shines most powerfully at the Equator

"Here, it powers an extraordinarily rich zone of life."

Brilliant and bizarre species from 3 continents... 3 oceans.

...more than a line on a map...

Equator is a powerful force of nature.

EQUATOR

Battle For The Light

"Around the Equator,"

dawn arrives

with staggering speed...

the new day rapidly unveils the lush rainforests of Southern Asia

Sunlight sweeps the tree tops at nearly 500 meters per second

"12 hrs of darkness ends,"

12 hours of light begins...

Life at the Equator is precisely tuned

to this dynamic daily rhythm.

These lush forests are driven by intense competition for light;

but even before that battle gets started -

another daily skirmish is underway -

the battle to be heard.

"Gibbons are early risers,"

heralding the light's return.

"Each pair duets,"

"one calling, the other listening,"

confirming bonds & declaring territories..

"In the gloomier branches below,"

a lone male orang-utan remains quiet in his night nest.

Orang-utans prefer to wake late.

"In the calm dawn air,"

Asia's many types of gibbon all warn off their neighbours

with vigorous operatic displays...

These singing apes are unique among primates -

both sexes use vocal displays to repel rivals..

"As the day brightens,"”

an array of voices struggles to be heard.

The hornbill is less operatic but has plenty of volume...

the hollow casqued above the bill amplifies calls

that can be heard over a huge area...

I!High up,!I

their sounds carry far... it is tougher down in the undergrowth...

"For small birds,"

"a high pitched call,"

repeated often is most effective...

"Another strategy is to broadcast at a precise frequency,"”

which differs from your neighbours.

This is how cicadas can attract a mate above all the din...

"Finally,"

the male orang-utan's baritone lays claim to his vast home range.

This is the most complex dawn chorus on the planet...

in Southern Asia you can hear the rich

diversity of life at the equator.

"As dawn's sound battle subsides,"

"the sun rises over forests of remarkably tall trees,"

some stretch over 80m high.

South Asian forests are dominated

by ancient trees known as dipterocarps.

"These giants cast a shadow over every living thing,"

controlling the daily "Battle for the Light'.

But these trees are 'selfish' giants -

"Not only do they grab most of the sunlight,”

but almost nothing can feed on their leaves...

that are filled with oily toxins called terpenes..

The dipterocarps massive cylindrical trunks

"have very few side branches,"

until they open out into mighty crowns.

Their shape creates wide gaps in the canopy-

aerial canyons that animals of Southern Asia have evolved

to cross in spectacular ways.

Most monkeys are brave leapers...

but they are no match for this creature's airborne skill.

The colugo is an expert glider - using the remarkable skin folds

"between its limbs and tail,"

it can soar 120 meters.

"Little is known about the life of this secretive nocturnal mammal,"

except that it's astonishing gliding skill has developed

for life in very tall branchless trees...

and it is by no means the only one.

In these forests even lizards can fly.

Draco lizards are miniature gliders

with their own elastic skin membranes

to carry them across the forest chasms.

And to avoid predators on the ground.

It's not just animals whose shape is moulded by the dipterocarps...

so are the trees below.

"Growing in the shadow of the selfish giants,"

smaller trees stretch toward the sunlight as spindly flexible poles...

just the right size for red apes on the move.

Using their weight

and immense strength to flex the saplings...

Orang utans can swing

and pole vault across the gaps with ease...

A prodigious memory helps them navigate huge distances

in search of favourite fruits.

"As the morning advances,"

"the little spider hunter flies its circuit of ginger flowers,"

probing for nectar and pollinating as it goes.

"After a long overnight fast,"

"many creatures need a floral sugar boost,"

to fuel their day.

"Throughout equatorial Asia,"

a fig tree in fruit is a magnet attracting morning diners

from far and wide...

"In Borneo,"

a rhinoceros hornbill

"and a rare helmeted hornbill arrive early,"

inspecting the ripeness of its tiny fruit..

The hornbills' long dextrous beaks

are perfectly designed for picking figs...

"but they must hurry,”

they won't have the tree to themselves for very long.

Gibbons are very aware of any ripening fruit

inside their territory...

and they have learnt the best pathways to reach it.

They use a neighbouring dipterocarp as their ladder...

and prepare for a hair-raising aerial assault..

The timid helmeted hornbill quickly retreats..

The rhinoceros hornbill moves to the outer branches

and plucks a few last morsels...

just as well...

these acrobatic apes are in no mood to share -

The tropical fig harvest is a vital oasis

within the desert of dipterocarp trees.

"Unlike the selfish giants,”

"which expend considerable energy creating toxins,"

the fig invests its energy reserves providing nutritious fruit.

"In return for this fruit,"

a succession of satisfied diners will carry away it's tiny seeds

in their stomachs.

Eventually the seeds will be sown far across the forest.

"But before they can keep their side of the bargain,”

"the gibbons face more life threatening leaps,"

back into their ladder tree...

"The gibbon family quickly departs in search of other tasty fruits,"

for which these forests are famous.

"Below the selfish giants,"

"many plants battle for their meagre share of the light,"

producing leaves that are lush and tasty...

Asian Elephants have a passion for palms...

Each adult eats 150 kgs of greens every day -

and a whole herd gives the forest a real thrashing...

"As they move and feed,"

they tear open new clearings;

"allowing the light to reach down to the forest floor,"

triggering re-growth...

the sun helps the forest to recover from a herd of hungry elephants.

But the light-starved under storey of Asia's forests

is shaped in a more subtle way

by its great diversity of monkeys and apes.

Many wild fruits in Equatorial Asia have tastes and aromas

that are irresistible to the palates of primates...

in return for some seed scattering.

"Thanks to their love of fruit,"

"mangosteens, lychees,"

durian & rambutan all thrive in these forests

and were enjoyed by monkeys and apes

long before their discovery by more recent primates... people!

Primates are fussy eaters &

"with such tropical abundance,"

they often discard more than they eat.

But there's a clean-up expert close at hand.

The bearded pig has a nose well-attuned

to the sun's fallen bounty.

With such riches raining down its not surprising

that bearded pigs are numerous and widespread.

Fruit scavengers are also attractive prey;

there are tigers in these forests.

İt pays to be watchful.

Even the rare

and poor sighted Sumatran rhino is drawn to the sound

and smell of fallen fruit.

"Be it hornbill above or rhinoceros below,"

all these large animals and birds

show just how generous

the lower forest plants are

compared to the impenetrable selfish giants..

Gathering fruit can be risky...

"Dangling 50 meters above a stony riverbed,"

an orang-utan mother has discovered a berry bonanza.

"Just as well red apes are careful,"

precise climbers.

They use three limbs gripping tightly at all times.

The mother seems unconcerned

about her 5 year old hanging precariously above her.

"At this tender age,"

he has already learnt from his mother where it is safe to climb

and what is safe to eat.

Far below other eager mouths are waiting.

Energy from the tree tops is never wasted.

"Where more berries fall than fruit scavengers can eat,"

"a few will sprout - the rest will decay,"”

returning nutrients to the tree they came from.

Fruiting trees and vines get extra nutrient payback -

dung and urine is most likely to fall under the trees

that are generous providers.

Here at the Equator the sun's heat drives decomposition

ten times faster than in cool climate forests.

Dung beetles kick-start the break up;

Within a few weeks most nutrients will be recycled

through the thin topsoil and back to the trees.

"Rainforest soils are depleted & poor,"

so trees don't bother with deep roots.

"Instead their mighty buttress roots sprawl over the surface,"

sending out shallow rootlets just below the leaf litter itself.

The greedy dipterocarp roots probe close to the surface

and enlist the help of soil fungi

to mine every last available mineral from the leaf litter.

Securing enough nutrients is never a problem

for one macabre plant;

"This is a rafflesia flower - at one metre across,”

it's the largest single flower in the world.

The blotchy petals resemble rotting flesh...

it also generates a foul smelling odour

and radiates subtle heat -

all designed to mimic a rotting corpse

so it's irresistible to the flies which pollinate it.

But how can rafflesia on the gloomy forest floor get enough energy

to fuel such lavish tactics?

"Not by its own efforts... it is a thief,"

a parasite that steals from a vine nearby.

This giant flower has no leaves

and no roots.

Its parasitic threads penetrate deep inside the vine.

The Rafflesia sucks all the nutrition

it needs from its host.

The host vine grows high into the treetops.

So the parasite is fed by the vines leaves.

"Lowly Rafflesia,"

"down on the forest floor,"

gains the full energy of the tropical sun.

Giant dipterocarps are the gatekeepers of light.

They take all the energy they need...

"but as the sun's rays penetrate the many layers of foliage,”

"they are filtered, scattered and reduced."

"Red & blue wavelengths are easily absorbed by most plants,"

whereas green light reflects off leafy surfaces.

That's why leaves appear green.

Its mostly green light that makes it to the forest floor.

Only 2% of the sunlight makes it this far...

...So bottom dwelling plants are adapted

to absorb the faintest light.

Corrugated leaves with prism -like

faces absorb scattered rays from every direction.

But forest floor plants must also cope

with the other extreme - brief bursts of full scorching sun...

The bottom dweller's leaves are protected

by waxy reflective coatings...

providing a sunscreen till the burning sun flecks pass by.

And the gloom returns.

Another tactic is producing red leaves -

these are better equipped

to absorb green light that dominates down here.

Red pigments can also be a sign that leaves contain bitter toxins

to deter grazing animals... at least in part...

and there are always plenty of grazers to deter.

Plants without toxins can pay a heavy price.

In tropical forests grazers never rest.

Some caterpillars are immune to plant toxins

and actually concentrate them in their bodies -

"so they too become toxic - causing their enemies to vomit,"

or even giving them heart failure.

Outlandish patterns and bold colours advertise their poisons...

Such colours are very effective warnings that can save lives.

"Of all the forest floor dwellers,"

"battling to make the most of the suns energy,"

the most tireless are ants...

they overwhelm anything they can carry home.

They are even bold enough to steal the crumbs

from a water monitor's mouth...

Until it can stand it no more.

"The ant world has its giants too,"

"like polyrachis, more than a centimetre long,"

it's a hundred times heavier than its neighbours...

"Preferring to forage solo,"

"they still communicate with their fellows,"

exchanging chemical tips on the latest dining place.

"They use vines as their highways,"

foraging all the way from the floor to the mid forest levels.

"Up here, mid way between the gloomy damp floor"

"and the full burning sun, living is pleasant,"

there's the ideal amount of day light.

Many plants here grow on top of others.

They are not parasites;

they perch on the branches of trees and include a thous

and varieties of beautiful orchids.

Many orchids can only grow near the Equator...

some are so sensitive a tiny drop in temperature can kill them...

But how have orchids succeeded

in colonising every corner of Asia's tropical forest?

One answer is their root systems that cling tenaciously

and can trap moisture from mist and showers.

But the real secret is in the way they travel.

The blooms of this tiny orchid are barely a millimetre across

and its minute seed heads are about to burst.

The microscopic seeds float on the breeze like specs of dust.

They're so light because they carry no food supply of their own.

"Once they crash I and,"

seeds rely on a special fungus to invade them.

Remarkably the invader provides the energy burst they need to sprout.

The orchid world is full of surprises...

This gently waving petal is not what it seems.

"It's an orchid mantis,"

brilliantly camouflaged & swaying in time

"with the breeze, as it sizes up a meal."

The fluffy sapsucker has also perfected the white on white look...

but those sticky threads would be unpleasant to eat...

The mantis wisely lets it pass.

"Now this is more like it, a real mantid-sized meal..."

"Preying mantids are voracious predators,"

"but when you rely on camouflage and ambush,"

it can be a very long wait between meals.

It's been 6 days since she last fed -

everything will be consumed except the scaly wings.

The battles between predator and prey are never ending...

but the daily battle for the light now takes a very different turn.

"At noon, the equatorial sun is at it's zenith..."

the problem now is not getting enough light...

but avoiding it.

The rhino wallows...

seeking relief from the heat and the flies with a mudpack.

The tiger uses its day wisely.

It rests now.

"With predators off duty,”

sun-loving butterflies have the flowers to themselves.

Everyone else avoids the sun... a siesta is a necessity.

Not all Asia's primates are canopy dwellers.

"Crab-eating macaques spend much of their time along stream edges,"

where there's plenty of shade to avoid the afternoon heat.

While the elders cool off by fishing for crabs

and tasty water snails... the youngsters splash and play.

Their antics have not gone unnoticed

It is too hot to be bothered chasing them now.

The tiger's battle will come later.

The sun's power has also been at work on forest...

"by mid afternoon,"

evaporation from billions of leaves is enough to change in the weather.

"Throughout the day,"

trees draw ever-more moisture into mighty buttresses

and up through massive trunks.

"Amazingly, these thin tubes transport water & nutrients,"

upwards against gravity for over 80 meters...

the destination is natures own solar panels - the leaves.

Water combines with carbon dioxide and light -

in the green miracle that is photosynthesis.

"Minute pores release the left over water vapour and oxygen,"

to be sucked out from the leaves

and out above the forest canopy... coalescing in to clouds.

Tropical forests are rain-making machines.

"A bear cat hurries her cub back to its den,"

before the rain unleashes its full force.

"Almost every day,"

equatorial forests are drenched...

5 meters of rain falls on Borneo and Sumatra each year.

Plants are well equipped for downpours...

"orang utans are too,"

their shaggy fur sheds rain...

but their best defence is their brains.

Regular afternoon rains top up the forest wallows.

"These are crucial breeding places, both for frogs and dragonflies.”

The dragonfly's larvae are predators...

they stalk these newly filled ponds.

The strength of the afternoon downpour

often topples old or weakened trees.

"When a giant falls,"

it opens up a light gap in the canopy -

& now the battle for the light suddenly gets' serious.

"Long dormant seedlings quickly sprout,”

then jostle upwards toward the light.

"It's a mad scramble to get there first,"

by whatever means.

The battle only ceases when the victors close the gap

with new foliage.

In the last hour of daylight most animals' attention returns to food.

"A huge male orang-utan has found a durian tree,”

laden with spiky fruit...

and the durian's pungent odour soon attracts an audience.

"The largest ape in the forest has spent the last 3 days here,"

devouring all the durian he can possibly eat.

His canines are powerful enough to crack the thick husk...

and no part of the delicious creamy pulp is wasted.

Durian fruit is designed to attract large mammals with keen noses...

such animals are big enough to swallow it's seeds whole

and to pass them undamaged with a fertilizer coating.

Finally he can eat no more.

Asian elephants are the ultimate durian fanciers...

they are drawn to this 'king of fruit' from far

"and wide by the pungent odour,"”

that's almost palpable...

but they are not the only ones lured here.

"For a young orang utan to cross the forest floor,"

there must be a real prize on offer..

Only a fruit

with a flavour 'to die for' is worth such a risk.

But getting inside this fallen gift of the sun is a different matter.

The durian has evolved to be eaten by forest giants

and she's not yet strong enough

to crack it... a frustrating stalemate.

Fallen durian are soon located by the biggest nose in Asia...

and finally the king of fruits has met its match -

dispatched with a single bite.

Asian Elephants also have an ancient relationship with Jackfruit -

these enormous fruit sprout directly from the trunk...

exactly at elephant height.

"A ten kilogram fruit is a jumbo sized mouthful,"

even for an elephant...

Such a problem requires a weighty solution.

"Sweet-scented jackfruit contains slippery seeds, easily swallowed"

and which will be passed a day later far away in the forest.

So the most powerful animal in Southern Asia

becomes the willing servant of the fragrant fruiting trees.

Just before sundown silvered leaf monkeys

should be finding a place to sleep.

"Instead they are on the move,"

heading for a late supper to be digested slowly overnight.

"It's a nervous time,"

but the troupe leaves a sentry on lookout...

"he remains vigilant,"

while the others descend to feed on grasses and tender shoots.

The Sumatran tiger has been waiting for the dusk...

this is its favourite time to hunt...

when mouse deer emerge from the thickets.

The tiny deer remain extremely alert

and are often first to sound an alarm.

Their battle is to stay alive...

"Tonight it's a leaf monkey that lost the twilight battle,"

paying the price for relaxing vigilance.

Day's end approaches as rapidly as it began.

As soft shadows rise up through the forest -

the battle for the light ceases...

at least for today.

The moment before sunset is when giant cicadas call...

and red flying squirrels appear.

The squirrels cautiously emerge from their tree holes...

before launching out between massive dipterocarp pillars.

"Having made a leap,"

"they climb as high as possible,”

before leaping again...

and so they move through the forest.

"With furry membranes between their limbs,"”

"but not their tail,"

they are not the most accomplished of the gliders here...

but they are well-adapted

to the challenge of moving between the tall trees...

another reminder of how dipterocarps have shaped many lives.

"The bloated male orangutan is ready for sleep,"

"adjusting his nest, to support his massive bulk."

The tree he sleeps in also enters a time of rest...

"Once photosynthesis stops,"

plant metabolism goes into reverse - leaves consume more oxygen

and energy than they produce.

The forest becomes like a massive solar battery

running down during the hours of darkness.

"The battle for daylight may be over,"

but battles between predator and prey only intensify.

Even nocturnal hunters are part of food chains

that lead back to the treetops and the energy of the equatorial sun.

The Asian Fishing Cat's night is off to a poor start.

"Just above wallows and ponds,"

tree frogs gather to lay their foamy egg masses.

"Once the eggs hatch, tadpoles wriggle out"

and drop in to the pond below.

"Where tree frogs gather,"

the red sided snake is never far away.

But this snake ignores the file-eared frog...

It prefers a much easier meal of frog spawn.

The fishing cat is persistent.

It stalks a fish still plump

with fallen berries.

"Nutrients that began high in the tree tops,"

are returned to land...

and soon to the forest itself.

"In the hours before dawn,"

the shy colugo is finally full of energy.

It searches out the most tender leaf tips...

varying it's diet to avoid an overdose of plant toxins.

But colugos have another newly discovered strategy.

They feed on sugar-rich tree sap...

including the poisonous sap of dipterocarps.

This mysterious mammal appears

to have conquered the dipterocarp's chemical defences...

as well as the chasms between their giant trunks.

"Of all tropical Asia's extraordinary creatures,"

the colugo seems the most directly moulded

by the selfish forest giants...

its perhaps their finest creation

Another dawn chorus announces that the battle

for the light is about to resume.

Only on the Equator could such a massed

choir of voices greet the return of each day.

Once again the mighty dipterocarp trees

"are first to soak up the sun's energy,"

casting their pervasive shadows on all below...