David Attenborough Madagascar (2011) s01e02 Episode Script
Lost Worlds
1 DAVID ATTENBOROUGH: Madagascar, an ancient island adrift in the Indian Ocean.
(BARKING) Its animals and plants, in isolation for millions of years, have evolved in their own way, so that now over 80% of them are unlike any others anywhere else in the world.
And by far, the greatest concentration of its highly-specialised wildlife is found here, among the mountains and rainforests of the east.
A journey down these eastern slopes, from isolated mountain peaks to tropical shorelines, reveals the huge variety of this island's wildlife.
160 million years ago, Madagascar lay between Africa and India within a much larger supercontinent called Gondwana.
As this giant landmass slowly broke apart, the upheavals created a 1,000-mile long range of mountains that stretch the length of Madagascar.
Separating west from east, the Andringitra highlands are one of the high points along this rocky backbone.
Over two and a half thousand metres high, they rise like inland islands far above the surrounding plains.
Over an immense span of time, these huge granite domes and plateaus have been sculpted by the elements.
The climate on these isolated tops is the most extreme found on this tropical island.
The days are scorching hot, the nights bitterly cold.
It appears deserted and yet, there is life here.
Usually found in warm forests, a few small troops of ring-tailed lemurs make their home in this desolate, windswept place.
To combat the cold they've evolved larger bodies and much thicker coats than their lowland relatives.
And they have another trick up their sleeves.
After spending the freezing nights huddled together in a crevice, they start the day with a spot of sunbathing.
(CHIRPING) Only drought-loving plants like aloe and cactus can survive in this high-altitude desert.
During the dry season, these succulent plants are the lemurs' only source of moisture.
It may be a tough, hand-to-mouth existence but they have few competitors up here.
Even so, venturing out on these exposed summits is not without its dangers.
Madagascar buzzards are quite capable of snatching an unwary lemur.
(LEMUR BARKING) A barked alarm call sends them all scuttling for cover.
(BARKING CONTINUES) (BARKING) Ring-tailed lemurs are just as suited to life on the ground as up in the trees.
And that makes them far more adaptable than most of Madagascar's lemurs.
Several troops of ring-tails manage to make a living in these highlands.
Some of the luckier ones occupy a more sheltered valley where a few trees have managed to take root.
Morning fog condensing on leaves is an important source of water.
(ANIMALS CALLING) Although the mornings still have a chill to them, life here seems more relaxed.
(SQUEAKING) But also more crowded.
(CAWING) Pied crows need to be moved on.
Not least because there are some vulnerable arrivals in the troop.
(CALLING) Almost every female is carrying an infant, an indication that life is comparatively easy up here.
With more protection from the elements and a little more food, this troop is particularly large and can devote plenty of time to their social lives.
(CHATTERING) One female even has twins, a rare event amongst ring-tailed lemurs and a direct result of a good food supply.
But this valley troop still has to work hard to collect food in this broken landscape.
Few lemurs are such good rock climbers.
There's a real bonanza at this time of year.
While some gather canopy fruits, the mother of the twins stays lower and gathers fresh leaves.
The young are born during the fruiting season when demands on the mothers are heaviest.
After such a heavy meal, the troop head off in search of their next course, the daily dose of dirt.
Eating soil is thought to help with digestion.
But it also provides minerals and even helps the lemurs to cope with troublesome gut parasites.
These troops are becoming even more isolated as farmers push up into the high valleys.
Now, surrounded by rice paddies, these highland lemurs are marooned in their mountaintop islands.
Here, away from the rest of their kind, they've had to adapt in order to survive.
(LEMUR CALLING FAINTLY) It's a story that's repeated all across these eastern mountains.
Each peak is effectively an island.
And each is home to its own unique collection of animals and plants.
This mountain range is home to one of these rarities, the Andringitra jeweled chameleon.
Swollen with eggs, this female is on a mission.
As the rainy season approaches, she begins to dig.
The only safe place for her clutch is deep underground.
But her first attempt ends in disaster.
Unearthing an ants' nest is not a good start.
She moves on and tries again.
She needs to find just the right spot.
Her eggs will remain hidden here for several months.
It takes her a whole day to excavate the nest.
Finally, she reverses in and lays around a dozen eggs.
(THUNDER RUMBLING) It becomes a race against time to get the eggs under cover.
She carefully hides her tracks.
And then she abandons her eggs to their fate.
(THUNDER CONTINUES RUMBLING) Madagascar's mountainous spine is the reason the island's eastern side is so wet.
It blocks the tropical winds blowing in from the Indian Ocean.
As the warm, moisture-laden air hits this barrier, rain condenses from the clouds and drenches these slopes.
Over five metres can fall here in a year.
Rain-swollen torrents pour over giant steps towards the ocean.
They descend into a richer, greener, more enclosed world.
The mist-shrouded Marojejy mountains lie in the northeast of the island.
These cloud forests are a rich many-layered world that offers huge opportunities for life to flourish.
One bird dominates the dark tangle of the understorey.
It's another of Madagascar's many oddities, the Helmet vanga.
These wet, eastern forests are its only home.
(CHIRPING) Why the Helmet vanga possesses such a vivid blue bill is a mystery.
But it's certainly a lethal weapon.
Vangas are ambush hunters, pouncing on ground-living millipedes or snatching cicadas and lizards from tree trunks.
Around 20 species of vanga live on the island, all descended from a single ancestral species that became isolated here millions of years ago.
(ANIMALS CALLING) There's a much more ghostly presence in these tangled forests, too.
The high canopy is home to one of the world's rarest primates.
There may be only 200 silky sifakas in existence.
Extremely sensitive to disturbance, these large lemurs have retreated to the region's most inaccessible valleys.
Leaves and flowers make up the bulk of their diet.
But such food is difficult to digest and they take long rests after each meal.
However, these essential halts do give them time to indulge their gentle, playful natures.
The whole family gets drawn into the games.
Even the older members, distinguished by their paler faces.
As with most lemurs, the female sifakas are only sexually receptive for 'gust one or two days each year.
So it's crucial for the males to keep a very close check on them.
The females leave scent marks on the tree trunks.
And the dominant males are quick to move in and check the subtle messages.
They can't afford to miss the one opportunity in the year to father a baby.
The name "lemur" means "spirits of the dead", and with only a few hundred of these brilliant white sifakas left, the name here could be only too prophetic.
Lower down the mountains, cloud forest gives way to warmer, wetter rainforests.
Great clumps of bamboo thrive in the tropical heat and damp.
The tangle of bowed and broken poles creates a natural climbing frame, a playground for one of Madagascar's most specialised group of animals.
Bamboo lemurs are Madagascar's pandas, depending almost entirely on this overgrown grass for food.
Bamboo is tough and woody.
Hard to chew, let alone digest.
But hardest of all, the leaves of some species are packed full of cyanide.
Yet, three species of bamboo lemur live here eating these plants day in, day out.
Two of them favour parts of the plant low in poison.
But the third, the golden bamboo lemur, is the real specialist.
It eats the tips of new leaves that are loaded with cyanide.
It's not known how they cope with the poison but they can tolerate up to 12 times a normally lethal dose.
Only through these subtle differences in diet can all three species share the same small patch of rainforest.
Bamboo thrives here because this part of Madagascar is very wet throughout the year.
And these lower eastern slopes are exposed to the full fury of the cyclone season.
For a few months each year, these powerful tropical storms sweep straight in from the Indian Ocean.
Lasting for days, they create paths of destruction across the island and pour huge amounts of water onto these forests.
But for the bamboo lemurs, these dark clouds have a silver lining.
In their wake, something peculiar starts springing up all over the forest floor.
It's what the lemurs have been waiting for all year, bamboo shoots.
The greater bamboo lemurs in particular find these spikes irresistible.
These new shoots are particularly rich in sugary sap.
It might take half an hour or more to consume a single shoot.
These bamboo-loving primates are one of the most highly-specialised animals to have evolved during Madagascar's long isolation.
But this has left them vulnerable as their forest home disappears.
As few as 1,000 of them now live in these dappled bamboo thickets.
The dense canopy means little light reaches the forest floor.
To survive in this shadowy world, animals need to blend in.
At just three centimetres long, this brown leaf chameleon is one of the smallest of its family.
Its long flattened body gives it excellent camouflage as it hunts among the debris of the forest floor.
(FLIES BUZZING) Today, it's also getting some help from upon high.
(LEMURS CALLING) This mess is being created by the largest of Madagascar's 80-odd lemurs, the indri, an unlikely ally for the tiny chameleon.
The fallen fruit is the perfect bait, attracting all sorts of insects, including swarms of fruit flies.
But this tiny predator has its sight set on something a little larger, a cockroach.
As night falls, the forest floor becomes a different world, where smell and sound and touch are the primary guides.
(INSECTS CHIRPING) (ANIMALS CALLING) A family of striped tenrecs starts truffling through the dead leaves.
They may look like hedgehogs, but tenrecs are unique to Madagascar.
And these striped tenrecs are only found here in these eastern rainforests.
One of the youngsters has been distracted by the discovery of a particularly juicy worm.
A ten rec's teeth are small, but needle-sharp and well-suited to dealing with this soft, slippery food.
By the time it's subdued its struggling prey, the rest of the family has moved on.
This is not a good place to be out on your own in the dark.
It needs to get back to its family.
But how to find them in the tangled undergrowth? They have a unique solution.
Specialised quills on their backs.
(QUILLS RATTLING) As these quills rub together, they create a high-pitched noise that cuts through the din of the forest.
It acts like a homing beacon, guiding wayward offspring back into the fold.
These are the only mammals in the world to communicate in this way.
Eastwards again towards the coastal lowlands.
All that stands in the way are the last cliffs and ravines of the escarpments.
As the gradient slackens, the rivers slow and spread.
Down here, the forests are even more luxuriant.
(CRICKETS CHIRPING) It's so wet that some tree frogs don't need to lay their eggs in water.
Instead, they stick them to the underside of leaves, well out of reach of hungry fish.
In less than a week, they've already developed into tadpoles.
They mature very quickly.
But not quite fast enough in this case.
(BUZZING) The most unlikely of predators has stumbled on these clumps of spawn.
The protective jelly merely slows down the wasp's smash-and-grab tactics.
The wasps return again and again, chewing up tadpoles before taking them back to their own nest.
And yet, the tadpoles aren't entirely helpless.
By the time they're only five days old, they're already able to react to the vibrations created by the hunting wasps.
They hatch prematurely when stressed like this and, as the jelly liquefies, the tadpoles dribble down to the leaf tip and into the water below.
They may be underdeveloped, but they can swim well enough to give themselves at least a fighting chance away from the jaws of the wasps circling above.
These lowland forests are full of sinister and unlikely predators.
Some plants have become meat eaters.
The shores of Lac Ampitabe are thick with pitcher plants.
(INSECT BUZZING) Their closest relatives are found in Indonesia, a place last connected to Madagascar 18 million years ago.
The liquid-filled cups are modified leaves.
Insects are attracted by the plant's bright patterns and sweet nectar.
But it's a fatal attraction.
The rim of the pitchers is very slippery.
And the sap appears to have a narcotic effect.
Once trapped inside, there's no escape.
Prey is slowly dissolved in the soup of enzymes secreted by the plant.
On this island of specialists, some creatures have even made this unwelcome place home.
Ants live in and around the pitchers collecting nectar from the rim.
Day geckos also sip at the sweet liquid, and hunt the insects attracted to the plants.
The ridged soles of their feet make them super sticky, able to grip on just about any surface.
But there are still dangers around these pitchers.
Striped snakes love this tangle of vegetation.
And eating geckos.
At the first hint of danger, the geckos retreat to the nearest cover.
An old dried-up pitcher is an excellent refuge.
In these forests, staying safe is often best done by keeping a low profile.
But paradise flycatchers are hard to miss.
(TWITTERING) And with their nest just a metre off the ground, the chicks are vulnerable to snakes and other birds.
Flycatchers, like many birds, have a trick that reduces the chance of their nest being discovered.
The chicks enclose their waste in white faecal sacks.
Just dumped over the side of the nest, these would attract a lot of unwelcome attention.
So the adults collect and dispose of them.
Others living in this forest don't seem to mind being the centre of attention.
This big, noisy bird is Madagascar's very own cuckoo.
(SH RILL CRY) All these calls are directed at its tiny foster parents.
Having disposed of their young long ago, this supersized impostor is monopolising their attention.
They seem unable to resist its incessant demands.
But now that the cuckoo is nearly full-grown, their exhausting ordeal will soon be over.
These lowland forests also contain a curious throwback, a plant that reveals a link to a time when Madagascar was still connected to mainland Africa.
The traveller's tree is only found in Madagascar, but its closest relatives are the bird-of-paradise flowers growing in southern Africa.
Over on the mainland, those plants are pollinated by nectar-feeding birds.
But in Madagascar, the traveller's tree has evolved to attract another pollinator.
Not a bird, but something altogether stranger.
The large flowers produce huge amounts of sugary nectar.
And they are tough enough to withstand rough handling.
And they need to be when aye-ayes come calling.
They may not look much like one, but the aye-aye is a lemur.
As it feeds, its snout becomes coated with pollen, which it then carries to other traveller's trees as it makes its nightly rounds of the forest.
For the aye-aye, nectar is just a passing fancy.
What's really shaped their extraordinary appearance is a love of beetle grubs.
Its large ears, gnawing teeth and long thin fingers, are all beautifully adapted to detect and winkle out juicy larvae from under the bark of rainforest trees.
In a few places, the rainforest extends right down to the ocean.
The largest stretch left in Madagascar grows on the remote Masoala Peninsula in the north of the island.
Here, there are hundreds of square miles of pristine jungle.
Growing right next to the ocean brings its own particular challenges.
The forest trees must cope with shifting sandy soils and being regularly showered with salty spray.
Nonetheless, the forest is full of wildlife.
(TWITTERING) Standing water can be hard to find here because the sandy soil drains so quickly.
That makes life very difficult for frogs looking for somewhere to lay their eggs.
But storm-damaged bamboo stalks provide the solution.
These rain-filled reservoirs are communal meeting places for Madagascar's unique golden bamboo frogs.
In the breeding season, this community spirit breaks down as individual males compete for the water-filled stems, and start calling to attract mates.
(FROGS CROAKING) In response, females are drawn to the males at their bamboo pools.
This female is a late arrival on the scene, and she needs to be very wary.
Another female has been here and there's already a tadpole in residence.
There's very little food in these pools.
And the last thing she wants is her valuable egg to end up feeding another female's tadpole.
So she rejects the male's advances and moves on.
Eventually, she finds an unoccupied pool, where she could be sure of laying the first egg.
And she has a way of getting around the shortage of food, too.
Once her egg is hatched, she'll return repeatedly to lay an infertile egg on which her tadpole will feed.
This is a highly-competitive world.
Predatory birds like couas and Madagascar coucals have leaf geckos on their menu.
But, first, they have to find them.
These geckos are able to stay absolutely motionless.
Some have evolved ragged fringes around their bodies to help break up their tell-tale outline.
The largest, up to 30 centimetres long, hide on favourite tree trunks that match their particular skin colouration.
But, as night falls, they're transformed.
The hunted become hunters.
Now it's not about camouflage, but stealth and surprise.
Their huge eyes help them track prey in the darkness.
Large mouths packed with sharp teeth help them tackle difficult prey.
But not necessarily to deal with smaller pests.
Their sight is 350 times more sensitive than the human eye.
These geckos can see colour even in the dimmest moonlight.
They have no eyelids, so licking is the only way to keep their eyes clean.
This caterpillar, apparently, doesn't taste good.
But a bad taste doesn't stop the gecko getting in a little retaliation.
The richness of these coastal forests is unrivalled on the island.
Although the Masoala rainforest covers only 2% of Madagascar's surface, over half of all the species found on the island are thought to live here.
The tallest trees of the peninsula's most remote valleys are home to one of its most spectacular inhabitants.
Red-ruffed lemurs are big and noisy.
(SQUAWKING) This troop has hit the jackpot.
Two trees, a fig and a harami, practically next door to each other, and both loaded with ripe fruit.
With so few seed-eating birds on the island, the trees rely on lemurs like the red-ruffs, to disperse their seeds through the forest.
After gorging all morning, the clan settles down nearby to sleep off their lunch.
But while most doze, one lemur stays behind.
It's his job to guard the trees from fruit robbers.
And in such a rich forest, a fruiting tree quickly becomes a magnet for other interested parties.
(PIGEON COOING) (SQUAWKING) Madagascar green-pigeons are quickly seen off.
A vasa parrot has slipped in under the lemur's guard.
But it makes little impact on the supply of figs.
Others need to be watched more carefully.
A gang of white-fronted brown lemurs has spotted the fruiting trees and want to share.
The males have striking white caps and they lead the raid.
(SQUAWKING) It takes the red-ruffed guardian a while to catch on to what's happening.
The brown lemurs are quick and agile.
And with ten of them and one of him, it's not that easy to get control of the situation.
By the time he's finally seen them off, the rest of the clan are on their way back to feed in the harami tree.
With food just an arm's length away, these particular lemurs appear to be living the good life, at least for the moment.
But red-ruffed lemurs are only found in this one stretch of coastal rainforest.
Their extreme specialisation, developed over millions of years, enables them to exploit every opportunity that this forest offers.
(SQUAWKING) But it also comes at a heavy cost.
It leaves them vulnerable if that opportunity disappears.
The few miles that separate Madagascar's highest mountains from these tropical shores are crowded with animals and plants, trapped in their own very narrow world.
And with these eastern forests rapidly disappearing, these unique worlds and their extraordinary inhabitants may soon be lost forever.
Working in Madagascar's most isolated corners is a real challenge.
And this trip to film red-ruffed lemurs proved to be one of the hardest.
For this shoot, cameraman john Brown and producer Ian Gray, have been joined by expert tree climbers Tim and Pam Fogg.
They will be responsible for getting john into the forest canopy, where these rare lemurs live.
The easiest way onto the Masoala Peninsula, a four-hour ride in a fast boat.
The crew rendezvous with their local guides at a little-used research station on this isolated coast.
They need to be entirely self-sufficient while working here.
(INAUDIBLE) That's the toilet.
Nice.
Luxurious, lovely.
Better than the huts outside.
ATTENBOROUGH: Red-ruffed lemurs are endangered, and these forested mountains are their last refuge.
It might seem like looking for a needle in a haystack, but the crew have a cunning plan.
(GRUNTS) Uphill all the way.
ATTENBOROUGH: Red-ruffed lemurs love to eat fruit.
So, find a fruiting tree and the red ruffs shouldn't be too far behind.
Oh, this is a cruel hill.
You just look up and it just goes on.
On and on up, hundreds of metres.
It's a brute.
ATTENBOROUGH: Then, on the second day of searching, they get a lucky break.
That tree looks like it's loaded with fruit.
Oh, yeah, yeah.
Can't see any lemurs, though.
No.
It's a lovely tree, though.
(LEMURS CALLING) BROWN: Those are definitely red ruffs.
Aren't they? Over there somewhere, I think.
ATTENBOROUGH: This is encouraging.
It's only the second day and things are looking distinctly promising.
But we've lucked out finally.
We found a big fruiting harami tree, just over the ridge here.
And there are red ruffs working in these trees.
And best thing is, there's another tree next door to it which we think we can get the platform into.
We'll see what tomorrow brings.
(THUNDER RUMBLING) ATTENBOROUGH: Rain.
Lots of it.
And this is supposed to be the dry season.
The tropical paradise is suddenly losing some of its glamour.
Hoping the rain will soon pass, the crew heads off into the forest to rig the filming platform so that it's ready when the weather improves.
But, if anything, the rain is getting worse.
(SQUAWKING) (INDISTINCT CONVERSATION) The hardest part is getting a line up into the tree.
This will be used to pull up a rope.
MAN: Yes! ATTENBOROUGH: And then haul up the filming platform and fix it in place.
(MEN LAUGHING) 30 metres up, this will put john level with the lemurs as they feed.
By the end of a very wet day, the only camera still working is on a mobile phone.
It's a bedraggled team that arrives back at camp.
Oh, dear.
ATTENBOROUGH: Everything has been thoroughly soaked.
The crucial thing now is to try and get the cameras dried out.
What's really annoying is you kind of know that the animal that you've come halfway around the world to film is probably doing exactly what we would want them to be doing, looking fantastic somewhere up a tree.
ATTENBOROUGH: All anyone can do is to be patient and hope for a change in the weather.
After eight long days, there's a small break in the clouds, so it's quickly back up the hill once again and onto the platform.
Well, this is day eight of the shoot and so far I've shot about two minutes of film, and it looks like there's another storm coming in across the bay that I can see.
(THUNDER RUMBLING) ATTENBOROUGH: As the storm breaks, being up a tree on a metal platform doesn't seem to be a good idea.
Time for another hasty retreat.
BROWN: So far, I'm not sure we're gonna get what we need.
But weâll just keep trying cause, well, what else can we do? ATTENBOROUGH: Desperate times call for desperate measures.
The key thing is to get rid of the condensation without melting the lens.
Day nine.
It's stopped raining.
No, it hasn't.
Still raining, and it rained all night, and we're all going absolutely stir crazy.
I see why you married him.
(LAUGHING) I think all of us could do with seeing the sun and getting dry underwear on.
That would make life a lot better.
ATTENBOROUGH: Finally, the storm fronts blow through.
It's time for one last slog back up to the platform.
So, after 10 days of trials and tribulations, and a lot of rain, we finally got john up in the tree, so now all we need are the red ruffs to come and do their stuff.
I can hear them calling already, so, hopefully, that's a good sign.
We're having a very strange meteorological phenomenon known as blue sky, and the lemurs have been in and feeding and sunbathing, and it's been just such a relief.
So, yeah, it's amazing what difference the weather makes.
(SQUAWKING) ATTENBOROUGH: In the next episode, we cross Madagascar's mountains into the southwest of the island, a land that is gripped by dryness for most of the year.
Among these dramatic landscapes, lives some of the strangest wildlife of all.
(BARKING) Its animals and plants, in isolation for millions of years, have evolved in their own way, so that now over 80% of them are unlike any others anywhere else in the world.
And by far, the greatest concentration of its highly-specialised wildlife is found here, among the mountains and rainforests of the east.
A journey down these eastern slopes, from isolated mountain peaks to tropical shorelines, reveals the huge variety of this island's wildlife.
160 million years ago, Madagascar lay between Africa and India within a much larger supercontinent called Gondwana.
As this giant landmass slowly broke apart, the upheavals created a 1,000-mile long range of mountains that stretch the length of Madagascar.
Separating west from east, the Andringitra highlands are one of the high points along this rocky backbone.
Over two and a half thousand metres high, they rise like inland islands far above the surrounding plains.
Over an immense span of time, these huge granite domes and plateaus have been sculpted by the elements.
The climate on these isolated tops is the most extreme found on this tropical island.
The days are scorching hot, the nights bitterly cold.
It appears deserted and yet, there is life here.
Usually found in warm forests, a few small troops of ring-tailed lemurs make their home in this desolate, windswept place.
To combat the cold they've evolved larger bodies and much thicker coats than their lowland relatives.
And they have another trick up their sleeves.
After spending the freezing nights huddled together in a crevice, they start the day with a spot of sunbathing.
(CHIRPING) Only drought-loving plants like aloe and cactus can survive in this high-altitude desert.
During the dry season, these succulent plants are the lemurs' only source of moisture.
It may be a tough, hand-to-mouth existence but they have few competitors up here.
Even so, venturing out on these exposed summits is not without its dangers.
Madagascar buzzards are quite capable of snatching an unwary lemur.
(LEMUR BARKING) A barked alarm call sends them all scuttling for cover.
(BARKING CONTINUES) (BARKING) Ring-tailed lemurs are just as suited to life on the ground as up in the trees.
And that makes them far more adaptable than most of Madagascar's lemurs.
Several troops of ring-tails manage to make a living in these highlands.
Some of the luckier ones occupy a more sheltered valley where a few trees have managed to take root.
Morning fog condensing on leaves is an important source of water.
(ANIMALS CALLING) Although the mornings still have a chill to them, life here seems more relaxed.
(SQUEAKING) But also more crowded.
(CAWING) Pied crows need to be moved on.
Not least because there are some vulnerable arrivals in the troop.
(CALLING) Almost every female is carrying an infant, an indication that life is comparatively easy up here.
With more protection from the elements and a little more food, this troop is particularly large and can devote plenty of time to their social lives.
(CHATTERING) One female even has twins, a rare event amongst ring-tailed lemurs and a direct result of a good food supply.
But this valley troop still has to work hard to collect food in this broken landscape.
Few lemurs are such good rock climbers.
There's a real bonanza at this time of year.
While some gather canopy fruits, the mother of the twins stays lower and gathers fresh leaves.
The young are born during the fruiting season when demands on the mothers are heaviest.
After such a heavy meal, the troop head off in search of their next course, the daily dose of dirt.
Eating soil is thought to help with digestion.
But it also provides minerals and even helps the lemurs to cope with troublesome gut parasites.
These troops are becoming even more isolated as farmers push up into the high valleys.
Now, surrounded by rice paddies, these highland lemurs are marooned in their mountaintop islands.
Here, away from the rest of their kind, they've had to adapt in order to survive.
(LEMUR CALLING FAINTLY) It's a story that's repeated all across these eastern mountains.
Each peak is effectively an island.
And each is home to its own unique collection of animals and plants.
This mountain range is home to one of these rarities, the Andringitra jeweled chameleon.
Swollen with eggs, this female is on a mission.
As the rainy season approaches, she begins to dig.
The only safe place for her clutch is deep underground.
But her first attempt ends in disaster.
Unearthing an ants' nest is not a good start.
She moves on and tries again.
She needs to find just the right spot.
Her eggs will remain hidden here for several months.
It takes her a whole day to excavate the nest.
Finally, she reverses in and lays around a dozen eggs.
(THUNDER RUMBLING) It becomes a race against time to get the eggs under cover.
She carefully hides her tracks.
And then she abandons her eggs to their fate.
(THUNDER CONTINUES RUMBLING) Madagascar's mountainous spine is the reason the island's eastern side is so wet.
It blocks the tropical winds blowing in from the Indian Ocean.
As the warm, moisture-laden air hits this barrier, rain condenses from the clouds and drenches these slopes.
Over five metres can fall here in a year.
Rain-swollen torrents pour over giant steps towards the ocean.
They descend into a richer, greener, more enclosed world.
The mist-shrouded Marojejy mountains lie in the northeast of the island.
These cloud forests are a rich many-layered world that offers huge opportunities for life to flourish.
One bird dominates the dark tangle of the understorey.
It's another of Madagascar's many oddities, the Helmet vanga.
These wet, eastern forests are its only home.
(CHIRPING) Why the Helmet vanga possesses such a vivid blue bill is a mystery.
But it's certainly a lethal weapon.
Vangas are ambush hunters, pouncing on ground-living millipedes or snatching cicadas and lizards from tree trunks.
Around 20 species of vanga live on the island, all descended from a single ancestral species that became isolated here millions of years ago.
(ANIMALS CALLING) There's a much more ghostly presence in these tangled forests, too.
The high canopy is home to one of the world's rarest primates.
There may be only 200 silky sifakas in existence.
Extremely sensitive to disturbance, these large lemurs have retreated to the region's most inaccessible valleys.
Leaves and flowers make up the bulk of their diet.
But such food is difficult to digest and they take long rests after each meal.
However, these essential halts do give them time to indulge their gentle, playful natures.
The whole family gets drawn into the games.
Even the older members, distinguished by their paler faces.
As with most lemurs, the female sifakas are only sexually receptive for 'gust one or two days each year.
So it's crucial for the males to keep a very close check on them.
The females leave scent marks on the tree trunks.
And the dominant males are quick to move in and check the subtle messages.
They can't afford to miss the one opportunity in the year to father a baby.
The name "lemur" means "spirits of the dead", and with only a few hundred of these brilliant white sifakas left, the name here could be only too prophetic.
Lower down the mountains, cloud forest gives way to warmer, wetter rainforests.
Great clumps of bamboo thrive in the tropical heat and damp.
The tangle of bowed and broken poles creates a natural climbing frame, a playground for one of Madagascar's most specialised group of animals.
Bamboo lemurs are Madagascar's pandas, depending almost entirely on this overgrown grass for food.
Bamboo is tough and woody.
Hard to chew, let alone digest.
But hardest of all, the leaves of some species are packed full of cyanide.
Yet, three species of bamboo lemur live here eating these plants day in, day out.
Two of them favour parts of the plant low in poison.
But the third, the golden bamboo lemur, is the real specialist.
It eats the tips of new leaves that are loaded with cyanide.
It's not known how they cope with the poison but they can tolerate up to 12 times a normally lethal dose.
Only through these subtle differences in diet can all three species share the same small patch of rainforest.
Bamboo thrives here because this part of Madagascar is very wet throughout the year.
And these lower eastern slopes are exposed to the full fury of the cyclone season.
For a few months each year, these powerful tropical storms sweep straight in from the Indian Ocean.
Lasting for days, they create paths of destruction across the island and pour huge amounts of water onto these forests.
But for the bamboo lemurs, these dark clouds have a silver lining.
In their wake, something peculiar starts springing up all over the forest floor.
It's what the lemurs have been waiting for all year, bamboo shoots.
The greater bamboo lemurs in particular find these spikes irresistible.
These new shoots are particularly rich in sugary sap.
It might take half an hour or more to consume a single shoot.
These bamboo-loving primates are one of the most highly-specialised animals to have evolved during Madagascar's long isolation.
But this has left them vulnerable as their forest home disappears.
As few as 1,000 of them now live in these dappled bamboo thickets.
The dense canopy means little light reaches the forest floor.
To survive in this shadowy world, animals need to blend in.
At just three centimetres long, this brown leaf chameleon is one of the smallest of its family.
Its long flattened body gives it excellent camouflage as it hunts among the debris of the forest floor.
(FLIES BUZZING) Today, it's also getting some help from upon high.
(LEMURS CALLING) This mess is being created by the largest of Madagascar's 80-odd lemurs, the indri, an unlikely ally for the tiny chameleon.
The fallen fruit is the perfect bait, attracting all sorts of insects, including swarms of fruit flies.
But this tiny predator has its sight set on something a little larger, a cockroach.
As night falls, the forest floor becomes a different world, where smell and sound and touch are the primary guides.
(INSECTS CHIRPING) (ANIMALS CALLING) A family of striped tenrecs starts truffling through the dead leaves.
They may look like hedgehogs, but tenrecs are unique to Madagascar.
And these striped tenrecs are only found here in these eastern rainforests.
One of the youngsters has been distracted by the discovery of a particularly juicy worm.
A ten rec's teeth are small, but needle-sharp and well-suited to dealing with this soft, slippery food.
By the time it's subdued its struggling prey, the rest of the family has moved on.
This is not a good place to be out on your own in the dark.
It needs to get back to its family.
But how to find them in the tangled undergrowth? They have a unique solution.
Specialised quills on their backs.
(QUILLS RATTLING) As these quills rub together, they create a high-pitched noise that cuts through the din of the forest.
It acts like a homing beacon, guiding wayward offspring back into the fold.
These are the only mammals in the world to communicate in this way.
Eastwards again towards the coastal lowlands.
All that stands in the way are the last cliffs and ravines of the escarpments.
As the gradient slackens, the rivers slow and spread.
Down here, the forests are even more luxuriant.
(CRICKETS CHIRPING) It's so wet that some tree frogs don't need to lay their eggs in water.
Instead, they stick them to the underside of leaves, well out of reach of hungry fish.
In less than a week, they've already developed into tadpoles.
They mature very quickly.
But not quite fast enough in this case.
(BUZZING) The most unlikely of predators has stumbled on these clumps of spawn.
The protective jelly merely slows down the wasp's smash-and-grab tactics.
The wasps return again and again, chewing up tadpoles before taking them back to their own nest.
And yet, the tadpoles aren't entirely helpless.
By the time they're only five days old, they're already able to react to the vibrations created by the hunting wasps.
They hatch prematurely when stressed like this and, as the jelly liquefies, the tadpoles dribble down to the leaf tip and into the water below.
They may be underdeveloped, but they can swim well enough to give themselves at least a fighting chance away from the jaws of the wasps circling above.
These lowland forests are full of sinister and unlikely predators.
Some plants have become meat eaters.
The shores of Lac Ampitabe are thick with pitcher plants.
(INSECT BUZZING) Their closest relatives are found in Indonesia, a place last connected to Madagascar 18 million years ago.
The liquid-filled cups are modified leaves.
Insects are attracted by the plant's bright patterns and sweet nectar.
But it's a fatal attraction.
The rim of the pitchers is very slippery.
And the sap appears to have a narcotic effect.
Once trapped inside, there's no escape.
Prey is slowly dissolved in the soup of enzymes secreted by the plant.
On this island of specialists, some creatures have even made this unwelcome place home.
Ants live in and around the pitchers collecting nectar from the rim.
Day geckos also sip at the sweet liquid, and hunt the insects attracted to the plants.
The ridged soles of their feet make them super sticky, able to grip on just about any surface.
But there are still dangers around these pitchers.
Striped snakes love this tangle of vegetation.
And eating geckos.
At the first hint of danger, the geckos retreat to the nearest cover.
An old dried-up pitcher is an excellent refuge.
In these forests, staying safe is often best done by keeping a low profile.
But paradise flycatchers are hard to miss.
(TWITTERING) And with their nest just a metre off the ground, the chicks are vulnerable to snakes and other birds.
Flycatchers, like many birds, have a trick that reduces the chance of their nest being discovered.
The chicks enclose their waste in white faecal sacks.
Just dumped over the side of the nest, these would attract a lot of unwelcome attention.
So the adults collect and dispose of them.
Others living in this forest don't seem to mind being the centre of attention.
This big, noisy bird is Madagascar's very own cuckoo.
(SH RILL CRY) All these calls are directed at its tiny foster parents.
Having disposed of their young long ago, this supersized impostor is monopolising their attention.
They seem unable to resist its incessant demands.
But now that the cuckoo is nearly full-grown, their exhausting ordeal will soon be over.
These lowland forests also contain a curious throwback, a plant that reveals a link to a time when Madagascar was still connected to mainland Africa.
The traveller's tree is only found in Madagascar, but its closest relatives are the bird-of-paradise flowers growing in southern Africa.
Over on the mainland, those plants are pollinated by nectar-feeding birds.
But in Madagascar, the traveller's tree has evolved to attract another pollinator.
Not a bird, but something altogether stranger.
The large flowers produce huge amounts of sugary nectar.
And they are tough enough to withstand rough handling.
And they need to be when aye-ayes come calling.
They may not look much like one, but the aye-aye is a lemur.
As it feeds, its snout becomes coated with pollen, which it then carries to other traveller's trees as it makes its nightly rounds of the forest.
For the aye-aye, nectar is just a passing fancy.
What's really shaped their extraordinary appearance is a love of beetle grubs.
Its large ears, gnawing teeth and long thin fingers, are all beautifully adapted to detect and winkle out juicy larvae from under the bark of rainforest trees.
In a few places, the rainforest extends right down to the ocean.
The largest stretch left in Madagascar grows on the remote Masoala Peninsula in the north of the island.
Here, there are hundreds of square miles of pristine jungle.
Growing right next to the ocean brings its own particular challenges.
The forest trees must cope with shifting sandy soils and being regularly showered with salty spray.
Nonetheless, the forest is full of wildlife.
(TWITTERING) Standing water can be hard to find here because the sandy soil drains so quickly.
That makes life very difficult for frogs looking for somewhere to lay their eggs.
But storm-damaged bamboo stalks provide the solution.
These rain-filled reservoirs are communal meeting places for Madagascar's unique golden bamboo frogs.
In the breeding season, this community spirit breaks down as individual males compete for the water-filled stems, and start calling to attract mates.
(FROGS CROAKING) In response, females are drawn to the males at their bamboo pools.
This female is a late arrival on the scene, and she needs to be very wary.
Another female has been here and there's already a tadpole in residence.
There's very little food in these pools.
And the last thing she wants is her valuable egg to end up feeding another female's tadpole.
So she rejects the male's advances and moves on.
Eventually, she finds an unoccupied pool, where she could be sure of laying the first egg.
And she has a way of getting around the shortage of food, too.
Once her egg is hatched, she'll return repeatedly to lay an infertile egg on which her tadpole will feed.
This is a highly-competitive world.
Predatory birds like couas and Madagascar coucals have leaf geckos on their menu.
But, first, they have to find them.
These geckos are able to stay absolutely motionless.
Some have evolved ragged fringes around their bodies to help break up their tell-tale outline.
The largest, up to 30 centimetres long, hide on favourite tree trunks that match their particular skin colouration.
But, as night falls, they're transformed.
The hunted become hunters.
Now it's not about camouflage, but stealth and surprise.
Their huge eyes help them track prey in the darkness.
Large mouths packed with sharp teeth help them tackle difficult prey.
But not necessarily to deal with smaller pests.
Their sight is 350 times more sensitive than the human eye.
These geckos can see colour even in the dimmest moonlight.
They have no eyelids, so licking is the only way to keep their eyes clean.
This caterpillar, apparently, doesn't taste good.
But a bad taste doesn't stop the gecko getting in a little retaliation.
The richness of these coastal forests is unrivalled on the island.
Although the Masoala rainforest covers only 2% of Madagascar's surface, over half of all the species found on the island are thought to live here.
The tallest trees of the peninsula's most remote valleys are home to one of its most spectacular inhabitants.
Red-ruffed lemurs are big and noisy.
(SQUAWKING) This troop has hit the jackpot.
Two trees, a fig and a harami, practically next door to each other, and both loaded with ripe fruit.
With so few seed-eating birds on the island, the trees rely on lemurs like the red-ruffs, to disperse their seeds through the forest.
After gorging all morning, the clan settles down nearby to sleep off their lunch.
But while most doze, one lemur stays behind.
It's his job to guard the trees from fruit robbers.
And in such a rich forest, a fruiting tree quickly becomes a magnet for other interested parties.
(PIGEON COOING) (SQUAWKING) Madagascar green-pigeons are quickly seen off.
A vasa parrot has slipped in under the lemur's guard.
But it makes little impact on the supply of figs.
Others need to be watched more carefully.
A gang of white-fronted brown lemurs has spotted the fruiting trees and want to share.
The males have striking white caps and they lead the raid.
(SQUAWKING) It takes the red-ruffed guardian a while to catch on to what's happening.
The brown lemurs are quick and agile.
And with ten of them and one of him, it's not that easy to get control of the situation.
By the time he's finally seen them off, the rest of the clan are on their way back to feed in the harami tree.
With food just an arm's length away, these particular lemurs appear to be living the good life, at least for the moment.
But red-ruffed lemurs are only found in this one stretch of coastal rainforest.
Their extreme specialisation, developed over millions of years, enables them to exploit every opportunity that this forest offers.
(SQUAWKING) But it also comes at a heavy cost.
It leaves them vulnerable if that opportunity disappears.
The few miles that separate Madagascar's highest mountains from these tropical shores are crowded with animals and plants, trapped in their own very narrow world.
And with these eastern forests rapidly disappearing, these unique worlds and their extraordinary inhabitants may soon be lost forever.
Working in Madagascar's most isolated corners is a real challenge.
And this trip to film red-ruffed lemurs proved to be one of the hardest.
For this shoot, cameraman john Brown and producer Ian Gray, have been joined by expert tree climbers Tim and Pam Fogg.
They will be responsible for getting john into the forest canopy, where these rare lemurs live.
The easiest way onto the Masoala Peninsula, a four-hour ride in a fast boat.
The crew rendezvous with their local guides at a little-used research station on this isolated coast.
They need to be entirely self-sufficient while working here.
(INAUDIBLE) That's the toilet.
Nice.
Luxurious, lovely.
Better than the huts outside.
ATTENBOROUGH: Red-ruffed lemurs are endangered, and these forested mountains are their last refuge.
It might seem like looking for a needle in a haystack, but the crew have a cunning plan.
(GRUNTS) Uphill all the way.
ATTENBOROUGH: Red-ruffed lemurs love to eat fruit.
So, find a fruiting tree and the red ruffs shouldn't be too far behind.
Oh, this is a cruel hill.
You just look up and it just goes on.
On and on up, hundreds of metres.
It's a brute.
ATTENBOROUGH: Then, on the second day of searching, they get a lucky break.
That tree looks like it's loaded with fruit.
Oh, yeah, yeah.
Can't see any lemurs, though.
No.
It's a lovely tree, though.
(LEMURS CALLING) BROWN: Those are definitely red ruffs.
Aren't they? Over there somewhere, I think.
ATTENBOROUGH: This is encouraging.
It's only the second day and things are looking distinctly promising.
But we've lucked out finally.
We found a big fruiting harami tree, just over the ridge here.
And there are red ruffs working in these trees.
And best thing is, there's another tree next door to it which we think we can get the platform into.
We'll see what tomorrow brings.
(THUNDER RUMBLING) ATTENBOROUGH: Rain.
Lots of it.
And this is supposed to be the dry season.
The tropical paradise is suddenly losing some of its glamour.
Hoping the rain will soon pass, the crew heads off into the forest to rig the filming platform so that it's ready when the weather improves.
But, if anything, the rain is getting worse.
(SQUAWKING) (INDISTINCT CONVERSATION) The hardest part is getting a line up into the tree.
This will be used to pull up a rope.
MAN: Yes! ATTENBOROUGH: And then haul up the filming platform and fix it in place.
(MEN LAUGHING) 30 metres up, this will put john level with the lemurs as they feed.
By the end of a very wet day, the only camera still working is on a mobile phone.
It's a bedraggled team that arrives back at camp.
Oh, dear.
ATTENBOROUGH: Everything has been thoroughly soaked.
The crucial thing now is to try and get the cameras dried out.
What's really annoying is you kind of know that the animal that you've come halfway around the world to film is probably doing exactly what we would want them to be doing, looking fantastic somewhere up a tree.
ATTENBOROUGH: All anyone can do is to be patient and hope for a change in the weather.
After eight long days, there's a small break in the clouds, so it's quickly back up the hill once again and onto the platform.
Well, this is day eight of the shoot and so far I've shot about two minutes of film, and it looks like there's another storm coming in across the bay that I can see.
(THUNDER RUMBLING) ATTENBOROUGH: As the storm breaks, being up a tree on a metal platform doesn't seem to be a good idea.
Time for another hasty retreat.
BROWN: So far, I'm not sure we're gonna get what we need.
But weâll just keep trying cause, well, what else can we do? ATTENBOROUGH: Desperate times call for desperate measures.
The key thing is to get rid of the condensation without melting the lens.
Day nine.
It's stopped raining.
No, it hasn't.
Still raining, and it rained all night, and we're all going absolutely stir crazy.
I see why you married him.
(LAUGHING) I think all of us could do with seeing the sun and getting dry underwear on.
That would make life a lot better.
ATTENBOROUGH: Finally, the storm fronts blow through.
It's time for one last slog back up to the platform.
So, after 10 days of trials and tribulations, and a lot of rain, we finally got john up in the tree, so now all we need are the red ruffs to come and do their stuff.
I can hear them calling already, so, hopefully, that's a good sign.
We're having a very strange meteorological phenomenon known as blue sky, and the lemurs have been in and feeding and sunbathing, and it's been just such a relief.
So, yeah, it's amazing what difference the weather makes.
(SQUAWKING) ATTENBOROUGH: In the next episode, we cross Madagascar's mountains into the southwest of the island, a land that is gripped by dryness for most of the year.
Among these dramatic landscapes, lives some of the strangest wildlife of all.