0:00:32 > 0:00:36Earth is the only planet we know of where life exists.
0:00:39 > 0:00:42And, here, it does so in abundance.
0:00:47 > 0:00:49The jungle is Eden.
0:00:52 > 0:00:56It covers less than 6% of the Earth's surface
0:00:56 > 0:00:58but it's home to half of all
0:00:58 > 0:01:00the plants and animals on land.
0:01:04 > 0:01:07Jungles have just the right amount of light,
0:01:07 > 0:01:12water and nutrients, and they have had every day for millennia.
0:01:17 > 0:01:20Life here should be easy.
0:01:28 > 0:01:30This is an indri.
0:01:33 > 0:01:35It's a primate, like us.
0:01:36 > 0:01:40And these forests in Madagascar are its home.
0:01:47 > 0:01:49But to survive here...
0:01:50 > 0:01:53..it has to face one major challenge.
0:01:59 > 0:02:01Paradise is crowded.
0:02:05 > 0:02:08Life fills every niche.
0:02:10 > 0:02:15And, at any one time, a staggering variety of species and countless
0:02:15 > 0:02:20individuals are striving for space and food.
0:02:29 > 0:02:31Like every jungle animal,
0:02:31 > 0:02:35indri have to find their own way to survive
0:02:35 > 0:02:38in the most competitive place on Earth.
0:02:41 > 0:02:42INDRI WAILS
0:02:44 > 0:02:46INDRI WAILS
0:03:03 > 0:03:05Jungles are complex places...
0:03:07 > 0:03:12..tangled three-dimensional worlds created by lush tropical vegetation.
0:03:17 > 0:03:2290% of the animals here spend their whole lives up in the trees.
0:03:23 > 0:03:26And each of them has to find its own way of getting around.
0:03:30 > 0:03:34Hanging 100 feet above the ground, a spider monkey.
0:03:40 > 0:03:45They travel in family groups and find everything they need in the top
0:03:45 > 0:03:46storey of the jungle.
0:03:48 > 0:03:51Up here isn't a place for the faint-hearted.
0:03:54 > 0:03:58With long limbs and a prehensile tail that can grip like a hand,
0:03:58 > 0:04:00they're built for climbing.
0:04:07 > 0:04:11But imagine having to learn these skills as high up as this.
0:04:17 > 0:04:21One third of spider monkeys never make it to adulthood.
0:04:24 > 0:04:27This youngster is only a few months old.
0:04:29 > 0:04:32Her future depends on her ability to climb.
0:04:35 > 0:04:39Playing on a practice tree with her older brother and sister,
0:04:39 > 0:04:42she's already learning to use her tail as a safety line...
0:04:46 > 0:04:49..under her father's close watch.
0:04:56 > 0:04:57THEY CHATTER
0:05:03 > 0:05:07She's keen to join in the game but she's the youngest and,
0:05:07 > 0:05:10as is the way of things, she's not always welcome.
0:05:14 > 0:05:15SHE GIBBERS
0:05:17 > 0:05:19So she chooses her own place to play.
0:05:26 > 0:05:28But not all trees are the same.
0:05:28 > 0:05:32This one is for more advanced climbers.
0:05:42 > 0:05:44Enthusiasm? Certainly!
0:05:49 > 0:05:50SHE GIBBERS
0:05:50 > 0:05:51Technique?
0:05:53 > 0:05:55SHE CHATTERS
0:05:55 > 0:05:56Room for improvement.
0:06:00 > 0:06:04Meanwhile, some of her family have moved on to look for a new patch of
0:06:04 > 0:06:05fresh food.
0:06:08 > 0:06:10The top of the canopy isn't for youngsters.
0:06:12 > 0:06:17But Father's not looking and the temptation to join the others is
0:06:17 > 0:06:18irresistible.
0:06:26 > 0:06:28She'll need to be careful.
0:06:28 > 0:06:31A fall from here would mean certain death.
0:06:39 > 0:06:43It's the first time she's been as high as this on her own.
0:06:54 > 0:06:58As she climbs still higher, the branches get thinner and thinner.
0:07:12 > 0:07:13SHE SCREECHES
0:07:15 > 0:07:17SHE SCREECHES
0:07:23 > 0:07:25Her tail has caught her...
0:07:25 > 0:07:30..but now she's stuck in mid-air, unable to reach any other branch.
0:07:32 > 0:07:33SHE SCREECHES
0:07:43 > 0:07:45Father, however, was watching.
0:07:48 > 0:07:52He's big and strong enough to form a bridge with his body so that she can
0:07:52 > 0:07:53climb to safety.
0:08:24 > 0:08:25Lesson learned.
0:08:31 > 0:08:35But it's not just monkeys that live here, up in the treetops.
0:08:43 > 0:08:48And, if you are small, finding the right tree can mean a home for life.
0:08:54 > 0:08:56He's a Draco lizard.
0:08:56 > 0:09:00He's only the size of a pencil and he eats ants.
0:09:08 > 0:09:13This one tree could provide him with all he will ever need -
0:09:13 > 0:09:14a conveyor belt of food.
0:09:18 > 0:09:20It's a perfect place to settle down.
0:09:27 > 0:09:29Well, it would be...
0:09:31 > 0:09:33..but there's already someone here.
0:09:42 > 0:09:46This larger male is the tree's owner.
0:09:46 > 0:09:48And Dracos don't share.
0:09:56 > 0:09:59The owner's flag is a warning.
0:10:03 > 0:10:05Trespassers won't be tolerated.
0:10:08 > 0:10:10The owner's not only intimidating...
0:10:13 > 0:10:14..he's prepared to battle.
0:10:27 > 0:10:28A dead end.
0:10:30 > 0:10:32Safety is a long way away.
0:10:35 > 0:10:37Now he must choose.
0:10:39 > 0:10:40Fight...
0:10:43 > 0:10:45..or flee?
0:11:02 > 0:11:06Only in the jungle do you find lizards that can soar like dragons.
0:11:10 > 0:11:14He can travel over 100 feet in a single leap.
0:11:16 > 0:11:20It's a very fast and efficient way to move through the jungle.
0:11:28 > 0:11:32Maybe this new tree will have food and no resident owner.
0:11:41 > 0:11:45Everything in the jungle has to compete for space.
0:11:50 > 0:11:53Only 2% of the sun's rays reach the ground...
0:11:54 > 0:11:56..so even the plants must battle for the light
0:11:56 > 0:11:58they need if they're to grow.
0:12:05 > 0:12:10300 years ago, this Hura tree began its race for light.
0:12:12 > 0:12:17And every day since, it has absorbed the water and sunshine it needed to
0:12:17 > 0:12:19grow into a giant.
0:12:28 > 0:12:33It has succeeded in doing what every tree must do to survive...
0:12:34 > 0:12:37..rise above the gloom of the jungle floor.
0:12:45 > 0:12:49And, what is more, its success has given life to others.
0:12:59 > 0:13:03Its branches now carry 1,000 other plants.
0:13:07 > 0:13:09These particular ferns,
0:13:09 > 0:13:13figs and orchids live only on the branches of other trees.
0:13:18 > 0:13:221,000 plants growing on one single tree.
0:13:24 > 0:13:29Throughout the forest, this story is repeated endless times.
0:13:33 > 0:13:36As a consequence, jungles are home
0:13:36 > 0:13:39to more species of plants than anywhere else on Earth.
0:13:41 > 0:13:45And they, in turn, support a wealth of animals.
0:13:50 > 0:13:54In Ecuador, the competition is at its most intense.
0:13:57 > 0:14:00Here, there are 100 species of hummingbirds alone...
0:14:03 > 0:14:05..all fighting for nectar.
0:14:08 > 0:14:11Each flower only has a small amount at any one time,
0:14:11 > 0:14:13and so it's first come, first served.
0:14:18 > 0:14:23One hummingbird has gone to great lengths to avoid conflict
0:14:23 > 0:14:25with other species.
0:14:29 > 0:14:33Swordbills are the only bird with a beak longer than their body.
0:14:36 > 0:14:40And some flowers are too elongated for the other 99 species of
0:14:40 > 0:14:43hummingbirds here to feed from them.
0:14:55 > 0:14:58A swordbill's extraordinary beak, however,
0:14:58 > 0:15:01enables it to reach the places that others can't...
0:15:05 > 0:15:09..the top of this flower, where the sweet nectar is produced.
0:15:11 > 0:15:16It has found a solution that means it doesn't have to join the fight.
0:15:19 > 0:15:23And, as each long flower blooms, it gives the swordbill a fresh supply
0:15:23 > 0:15:25of food all to itself.
0:15:41 > 0:15:45But having a beak longer than your body does have its drawbacks.
0:15:50 > 0:15:52For a start, it's tricky to keep it clean.
0:16:05 > 0:16:08Harder still, how do you preen your body feathers?
0:16:11 > 0:16:13Unlike the other hummers,
0:16:13 > 0:16:16swordbills can't reach their feathers with their beak.
0:16:23 > 0:16:27The only option, a good old scratch.
0:16:46 > 0:16:47It's a little unrefined...
0:16:50 > 0:16:54..but a small price to pay for an exclusive food supply...
0:16:58 > 0:17:03..especially when feeding times are only too frequently interrupted
0:17:03 > 0:17:05by storms.
0:17:05 > 0:17:08THUNDER RUMBLES
0:17:12 > 0:17:15Jungles are the richest places on Earth
0:17:15 > 0:17:17because of one remarkable fact...
0:17:20 > 0:17:22..they make their own weather.
0:17:28 > 0:17:32Every day, water rises from the surface of the leaves as vapour.
0:17:35 > 0:17:38It's as if the trees breathe out clouds.
0:17:41 > 0:17:44They gather over the forest until, finally...
0:17:47 > 0:17:48..they burst.
0:18:03 > 0:18:07Rain is the lifeblood of every jungle.
0:18:16 > 0:18:20And all have to do their best to endure the daily downpour.
0:19:03 > 0:19:06In some jungles, like here in Brazil,
0:19:06 > 0:19:10it rains so much that, for part of the year, the trees are
0:19:10 > 0:19:12almost totally submerged.
0:19:21 > 0:19:25The forest floor is 30 feet below the water's surface.
0:19:28 > 0:19:34This is a mysterious world, a place few people have ever explored.
0:19:43 > 0:19:47We have much to discover about the animals for which this is home...
0:19:52 > 0:19:57..including some you might never expect to find amongst trees.
0:20:11 > 0:20:16Here, 1,000 miles from the sea, are dolphins.
0:20:21 > 0:20:26A newly identified species of river dolphin found nowhere else on Earth.
0:20:38 > 0:20:39DOLPHIN WHISTLES
0:20:39 > 0:20:45In these black, tangled waters, they have become almost totally blind,
0:20:45 > 0:20:47so they move slowly,
0:20:47 > 0:20:51carefully using their sonar to scan the forest floor for fish.
0:20:57 > 0:21:00If this forest can hide a new species of dolphin...
0:21:02 > 0:21:04..what else might there be here, awaiting discovery?
0:21:11 > 0:21:13At the shallow margins of the flooded jungle,
0:21:13 > 0:21:16rivers flow through lush vegetation.
0:21:20 > 0:21:24Here, food is so abundant, it supports giants.
0:21:27 > 0:21:30Capybara, the biggest rodents in the world...
0:21:32 > 0:21:33GRUNTING
0:21:36 > 0:21:38..giant otters the size of a man...
0:21:39 > 0:21:40THEY SQUEAK
0:21:43 > 0:21:45..and the rulers of these rivers...
0:21:45 > 0:21:47SPLASH
0:21:47 > 0:21:48..caiman.
0:21:50 > 0:21:52They grow to ten feet long and kill anything
0:21:52 > 0:21:54they get between their jaws.
0:22:00 > 0:22:03But there are more artful hunters...
0:22:05 > 0:22:07..drawn here from the surrounding forest.
0:22:20 > 0:22:23A jaguar, the supreme jungle predator.
0:22:31 > 0:22:34The river marks the edge of his territory...
0:22:36 > 0:22:38..but here he has competition.
0:22:41 > 0:22:43THEY GROWL
0:22:44 > 0:22:46THEY ROAR
0:22:55 > 0:22:58THEY GROWL
0:23:01 > 0:23:03He's now in the territory of a female.
0:23:09 > 0:23:13She has ruled this stretch of river for five years.
0:23:15 > 0:23:18This is her place to hunt.
0:23:47 > 0:23:50Capybara are strong and wary.
0:23:54 > 0:23:55The key is stealth.
0:24:14 > 0:24:18She needs to get within three feet if she's to pounce.
0:24:41 > 0:24:42Not this time.
0:24:53 > 0:24:55She's not the only female here.
0:24:57 > 0:25:01Each part of this jungle's edge is ruled by a different queen.
0:25:12 > 0:25:17Few places on Earth have enough food to support so many big cats.
0:25:22 > 0:25:24LOW GROWL
0:25:43 > 0:25:46The male hunts in a different way.
0:25:53 > 0:25:57Weighing almost 300 lbs, it's hard to be stealthy...
0:26:01 > 0:26:04..and with so many other jaguars around,
0:26:04 > 0:26:06he doesn't bother with wary capybara.
0:26:13 > 0:26:15He seeks a different prey.
0:26:38 > 0:26:41He's become a killer
0:26:41 > 0:26:42of killers.
0:27:08 > 0:27:13Jaguars have the most powerful bite of any cat.
0:27:16 > 0:27:20And he knows the caiman's most vulnerable point...
0:27:22 > 0:27:24..the back of its skull.
0:27:25 > 0:27:27CRUNCHING
0:27:51 > 0:27:55Hunters living in the dense understorey of the jungle
0:27:55 > 0:27:58come in all shapes and sizes.
0:28:00 > 0:28:02But they share a problem.
0:28:09 > 0:28:12How to tell what is a plant, and what is prey.
0:28:16 > 0:28:20This is a game of hide and seek that can be won or lost
0:28:20 > 0:28:22in the blink of an eye.
0:28:52 > 0:28:56The long contest between predator and prey
0:28:56 > 0:28:59has produced mimicry of astounding accuracy.
0:29:17 > 0:29:21A leaf-tailed gecko masquerading as lichen.
0:29:46 > 0:29:51Some animals take camouflage a stage further still...
0:29:55 > 0:29:57..and these streams in Costa Rica
0:29:57 > 0:30:00are home to one of the most remarkable.
0:30:11 > 0:30:12A glass frog.
0:30:20 > 0:30:26A male, and tiny, no bigger than your fingernail
0:30:26 > 0:30:29and almost entirely transparent...
0:30:31 > 0:30:33..as he needs to be.
0:30:36 > 0:30:41Almost everything that walks past here could eat him,
0:30:41 > 0:30:43even a cricket.
0:30:48 > 0:30:52His best chance is to stay absolutely still and trust that
0:30:52 > 0:30:54the cricket looks right through him.
0:31:16 > 0:31:19Danger passed,
0:31:19 > 0:31:23and that's just as well,
0:31:23 > 0:31:25because he is a father...
0:31:28 > 0:31:31..and he's guarding some very precious eggs.
0:31:35 > 0:31:39For the last few weeks, females, one after the other,
0:31:39 > 0:31:42have visited him and entrusted him with their offspring.
0:31:45 > 0:31:48Some are now almost ready to hatch.
0:31:52 > 0:31:56There are several clutches on the leaf, and those at the top,
0:31:56 > 0:31:59the most recently laid, are barely a day old.
0:32:06 > 0:32:09But in the jungle, there's always someone out to get you.
0:32:15 > 0:32:20This wasp is a specialist hunter of frogs' eggs.
0:32:22 > 0:32:26It's noticed the wriggling tadpoles at the bottom of the leaf.
0:32:32 > 0:32:33He mustn't move.
0:32:34 > 0:32:37The youngest eggs are the most vulnerable,
0:32:37 > 0:32:39and he can't guard them all.
0:32:58 > 0:33:02But these tadpoles are not as helpless as they might appear.
0:33:11 > 0:33:15Incredibly, the unhatched tadpoles can sense danger,
0:33:15 > 0:33:20and the oldest and strongest wriggle free and drop into the stream below.
0:33:38 > 0:33:41The eggs at the top of the leaf, however,
0:33:41 > 0:33:44are still too young to hatch,
0:33:44 > 0:33:47and now the wasps know they're there.
0:33:51 > 0:33:56But the male's back looks very like the youngest cluster of eggs...
0:34:00 > 0:34:03..and that seems to confuse the wasps.
0:34:25 > 0:34:28Using his own body as a decoy is a huge risk.
0:34:29 > 0:34:31The wasp stings could kill him.
0:34:59 > 0:35:02He's managed to save most of his young.
0:35:07 > 0:35:12He'll have to remain on guard for another two weeks,
0:35:12 > 0:35:17but in the jungle, just surviving the day can count as a success.
0:35:31 > 0:35:33With the coming of the night,
0:35:33 > 0:35:37a new cast of jungle characters takes to the stage.
0:35:41 > 0:35:45Flying insects begin to glow as they search for mates.
0:35:50 > 0:35:54Fungi, unlike plants, thrive in the darkness of the forest floor.
0:35:57 > 0:36:01They're hidden until they begin to develop the incredible structures
0:36:01 > 0:36:03with which they reproduce.
0:36:06 > 0:36:10Each releases millions of microscopic spores
0:36:10 > 0:36:12that drift invisibly away.
0:36:17 > 0:36:22Many have fruiting bodies that reach upwards to catch any feeble current
0:36:22 > 0:36:24there might be in the clammy air.
0:36:28 > 0:36:31But this one, as it grows,
0:36:31 > 0:36:33becomes luminous.
0:36:46 > 0:36:49Why fungi light up has remained a mystery...
0:36:56 > 0:36:57..until now.
0:37:06 > 0:37:09Scientists studying the brightest fungi in the world
0:37:09 > 0:37:12think they may have an answer.
0:37:17 > 0:37:20Like a beacon, the light attracts insects.
0:37:27 > 0:37:28From far and wide.
0:37:37 > 0:37:41To this click beetle, a bright light means only one thing -
0:37:41 > 0:37:45a female click beetle,
0:37:45 > 0:37:46so he flashes in reply.
0:37:58 > 0:38:01But he doesn't get the reception he was expecting.
0:38:06 > 0:38:11Confused, he starts searching for a female, and that helps the fungus.
0:38:13 > 0:38:17By the time he gives up, he's covered in the fungus's spores.
0:38:19 > 0:38:21And, as he continues his quest for a female,
0:38:21 > 0:38:25he carries these spores to other parts of the forest.
0:38:28 > 0:38:33And there are even stranger things glowing in the jungle night.
0:38:37 > 0:38:41These are the multicoloured lights of a railroad worm.
0:38:43 > 0:38:48It's not really a worm, but a poisonous, caterpillar-like beetle.
0:38:51 > 0:38:55The yellow lights warn other creatures to keep out of its way.
0:39:04 > 0:39:07It's hunting for millipedes.
0:39:17 > 0:39:22When it finds the trail of one, it switches off its yellow lights.
0:39:28 > 0:39:32Now it only has a red light on its head.
0:39:37 > 0:39:40Millipedes can't see red light.
0:39:45 > 0:39:51So, to them, the railroad worm in stealth mode is virtually invisible.
0:40:03 > 0:40:06And that is the end of the millipede.
0:40:18 > 0:40:22Competition in the jungles forces animals to specialise
0:40:22 > 0:40:25in every aspect of their life,
0:40:25 > 0:40:27including courtship.
0:40:29 > 0:40:34This has produced some of the most beautiful and elaborate displays
0:40:34 > 0:40:35on the planet.
0:40:38 > 0:40:43BIRD SQUAWKS
0:40:38 > 0:40:43A male red bird-of-paradise,
0:40:43 > 0:40:47competing to attract a female by dancing.
0:40:49 > 0:40:51One has come to survey what's on offer.
0:41:09 > 0:41:11She is an independent lady,
0:41:11 > 0:41:16and she will select whichever male takes her fancy.
0:41:16 > 0:41:18BIRDS SQUAWKING
0:41:32 > 0:41:34She makes her choice.
0:41:52 > 0:41:55But now she doesn't seem quite so sure.
0:42:03 > 0:42:08No? Perhaps he's just a little too keen.
0:42:22 > 0:42:24Maybe he'll have better luck tomorrow.
0:42:33 > 0:42:36Red birds-of-paradise display in the treetops.
0:42:40 > 0:42:44Other members of the family dance in the gloom of the forest floor.
0:42:47 > 0:42:50This is a Wilson's bird-of-paradise.
0:42:52 > 0:42:55He's brightly coloured, but about the size of a sparrow.
0:42:59 > 0:43:04He's lived most of his life alone, but now he's an adult,
0:43:04 > 0:43:06and he too needs to attract a mate.
0:43:11 > 0:43:14This little patch of light might help him do so.
0:43:20 > 0:43:23First, he tidies things up.
0:43:23 > 0:43:28Showing off in this jumble of leaves wouldn't be easy,
0:43:28 > 0:43:33and his beauty will stand out better against a plain background.
0:43:41 > 0:43:45He doesn't want bright leaves to divert a visitor's attention.
0:43:45 > 0:43:47They all need to go.
0:43:51 > 0:43:52Even the green ones.
0:43:55 > 0:43:57Especially the green ones.
0:44:06 > 0:44:09His stage is set.
0:44:09 > 0:44:12A central pole, and a little patch of light.
0:44:12 > 0:44:13It's perfect.
0:44:17 > 0:44:21And now, he must hope a female hears his call.
0:44:21 > 0:44:22HIGH-PITCHED SQUAWKING
0:44:32 > 0:44:34He can wait here for weeks on end.
0:44:44 > 0:44:46At last, a female.
0:44:49 > 0:44:51Time to take up position.
0:44:54 > 0:44:57She will judge him by the brightness of his feathers.
0:45:03 > 0:45:06But for the female to see him at his best,
0:45:06 > 0:45:11he needs her to perch directly above his stage,
0:45:11 > 0:45:13under the light.
0:45:16 > 0:45:20This might be his only chance to shine.
0:45:26 > 0:45:31Now, when she's looking directly down on him, he reveals a display
0:45:31 > 0:45:33for her eyes only.
0:45:39 > 0:45:41In the gloom of the forest floor,
0:45:41 > 0:45:45he is a dazzling blaze of iridescent green.
0:45:47 > 0:45:49The brightest leaf in the forest.
0:45:58 > 0:46:00And that does the trick.
0:46:10 > 0:46:14Each animal must find its own way of surviving the competition
0:46:14 > 0:46:15of the jungle.
0:46:28 > 0:46:33This crowded world is so full of invention that almost all kinds
0:46:33 > 0:46:37of animals on land can trace their origins back here...
0:46:42 > 0:46:44..including us.
0:46:47 > 0:46:52These forests in Madagascar are home to one of our distant cousins.
0:46:56 > 0:47:01This female indri has fought to keep this particular patch of forest
0:47:01 > 0:47:04safe for herself and her family.
0:47:04 > 0:47:08HIGH-PITCHED SHRIEKS
0:47:14 > 0:47:18Every morning, the family come together to sing,
0:47:18 > 0:47:22their way of reminding others that this is their home.
0:47:28 > 0:47:32Indri are so closely adapted to living here
0:47:32 > 0:47:35that now they can live nowhere else.
0:47:39 > 0:47:44For them and the billions of animals with whom they share their home,
0:47:44 > 0:47:46the jungle is a sanctuary.
0:47:51 > 0:47:52But this is changing.
0:47:57 > 0:48:00Even in the ten years since the head of this family was born,
0:48:00 > 0:48:04one million hectares of the rainforest have been destroyed
0:48:04 > 0:48:08in Madagascar alone,
0:48:08 > 0:48:12and, with it, half the indri families that once lived there.
0:48:17 > 0:48:22The local people say the indris are our brothers and their song is
0:48:22 > 0:48:26a call to remind us that we, too, once depended on the jungle.
0:48:35 > 0:48:40This Eden is still a place of wonder and magic.
0:48:45 > 0:48:48Something, surely, worth protecting.
0:49:07 > 0:49:10Jungles are still some of the least explored places on Earth,
0:49:10 > 0:49:13and with good reason.
0:49:13 > 0:49:14They are testing places to work.
0:49:18 > 0:49:21Here in the flooded forests of Brazil,
0:49:21 > 0:49:25the team are on the trail of a newly discovered species of river dolphin.
0:49:27 > 0:49:31So little is known about it that just finding it will be a challenge.
0:49:32 > 0:49:38Their base for five weeks is a hut on the only bit of dry land around,
0:49:38 > 0:49:41but it's already occupied.
0:49:41 > 0:49:43It appears someone's been making a nest.
0:49:43 > 0:49:45A resident rat.
0:49:45 > 0:49:49Hello, little rat. And on the food cupboard...
0:49:49 > 0:49:52Hello. Are you a bit shy?
0:49:56 > 0:50:00If the housemates are hostile, the hitchhikers are even worse.
0:50:02 > 0:50:04A large spider.
0:50:05 > 0:50:06Oh, my God.
0:50:08 > 0:50:11And a colony of aggressive red ants looking for a ride.
0:50:11 > 0:50:14Shall we knock into them?
0:50:14 > 0:50:17They'll board the boat like a bunch of pirates,
0:50:17 > 0:50:19and they'll gnaw our faces off.
0:50:22 > 0:50:24That might not be quite true,
0:50:24 > 0:50:27but intimidating animals are the least of their problems.
0:50:30 > 0:50:32The flooded forest is not only vast,
0:50:32 > 0:50:37it's impenetrable, and this new species of dolphin could be anywhere
0:50:37 > 0:50:41in 150,000 square miles of tangled treetops.
0:50:43 > 0:50:45But the crew have a plan.
0:50:46 > 0:50:50Dolphins use sound to find their way through the flooded forest
0:50:50 > 0:50:51by making clicks. Sonar.
0:50:53 > 0:50:57Waterproof microphones allow the crew to eavesdrop on the dolphins,
0:50:57 > 0:50:58and so follow them.
0:51:02 > 0:51:04But that's easier said than done.
0:51:08 > 0:51:11So, this is the clear path.
0:51:11 > 0:51:13Can you see it? There.
0:51:20 > 0:51:24It takes them a week to get their first glimpse of this new species,
0:51:24 > 0:51:27and even then, it lasts less than a second.
0:51:30 > 0:51:32There appears to be only one dolphin.
0:51:36 > 0:51:40And, frustratingly, it can pop up anywhere without warning.
0:51:43 > 0:51:46Been looking through the water and seeing bodies kind of appear
0:51:46 > 0:51:50out of the murk, and then disappear again.
0:51:53 > 0:51:56Eventually, the dolphin leads the crew to an open gap in the forest.
0:52:07 > 0:52:10We made it! Yay!
0:52:13 > 0:52:16Here, at last, there may be a chance of getting something in the can.
0:52:24 > 0:52:28Their first shot, but again, a single breath, and then it's gone.
0:52:33 > 0:52:37Hello, you. With the dolphin as close as this,
0:52:37 > 0:52:39the crew can try a different technique -
0:52:39 > 0:52:42towing an underwater camera behind the boat.
0:52:45 > 0:52:48Dolphin literally just came up parallel to it.
0:52:49 > 0:52:53The problem is that the water is so murky, that the dolphin is
0:52:53 > 0:52:55almost invisible, even when right next to the camera.
0:53:03 > 0:53:06However, now the dolphin is in this channel,
0:53:06 > 0:53:07the crew can try a different tack.
0:53:16 > 0:53:19Michael Sanderson is a drone operator.
0:53:22 > 0:53:24As long as the dolphin's in open water,
0:53:24 > 0:53:26it might be possible to follow it from the air.
0:53:31 > 0:53:33We've worked out the dolphins seem to be here,
0:53:33 > 0:53:37and we can do the drone work, so this is our kind of best bet.
0:53:38 > 0:53:41Leaving Michael and his drone on the sand spit,
0:53:41 > 0:53:43the crew head back to open water.
0:53:44 > 0:53:47But this is called the flooded forest for a reason.
0:53:50 > 0:53:52The rain here can be torrential,
0:53:52 > 0:53:55and although storms normally pass quickly,
0:53:55 > 0:53:57this one is clearly not a normal storm.
0:54:02 > 0:54:04Is it not working?
0:54:04 > 0:54:07The motor has broken, and with the boat flooding,
0:54:07 > 0:54:09the crew must head for the bank.
0:54:15 > 0:54:17It looked like the rainstorm was going to pass,
0:54:17 > 0:54:20and it hasn't passed at all. It's very, very heavy,
0:54:20 > 0:54:22and I'm soaked through to the skin.
0:54:26 > 0:54:30They're stranded, the kit is getting drenched,
0:54:30 > 0:54:33trees are falling, and Michael is trapped somewhere down-river.
0:54:33 > 0:54:37This is the hardest rain I've ever seen in my life.
0:54:37 > 0:54:41It's incredible. I'm hoping Michael's all right.
0:54:41 > 0:54:44And there's been tree fall all up around behind us.
0:54:44 > 0:54:47Michael's down there on a tiny little sand spit,
0:54:47 > 0:54:50with the other boat, with his opticopter out.
0:54:52 > 0:54:53Kind of scary.
0:54:55 > 0:54:57After two hours,
0:54:57 > 0:55:00a break in the storm gives Michael a chance to rejoin the team.
0:55:00 > 0:55:04Just got caught in one of the heaviest storms I've ever seen.
0:55:04 > 0:55:09Got up to this much water on the tarp, and the other one, so
0:55:09 > 0:55:12I don't know if this is going to live any more,
0:55:12 > 0:55:15because that was on the floor.
0:55:15 > 0:55:18It looks like it's game over for the drone.
0:55:18 > 0:55:20Yeah, it was pretty scary, wasn't it?
0:55:22 > 0:55:26Over the next 12 hours, the storm returns again and again.
0:55:28 > 0:55:29If this bad weather continues,
0:55:29 > 0:55:32the crew may not be able to get back out to the dolphin.
0:55:38 > 0:55:41The next morning,
0:55:41 > 0:55:44clear skies, and the drone might be fixable.
0:55:45 > 0:55:48But the longer it takes, the more chance that the dolphin
0:55:48 > 0:55:52will have returned to the flooded forest,
0:55:52 > 0:55:53and then it'll be back to square one.
0:55:56 > 0:55:58But finally, their luck is in.
0:56:00 > 0:56:02The dolphin is still there.
0:56:05 > 0:56:07For the first time, they have a chance to film
0:56:07 > 0:56:10from the water and the air, and finally discover
0:56:10 > 0:56:13what this elusive animal is really doing.
0:56:14 > 0:56:17They were in the boat and they were looking around and going,
0:56:17 > 0:56:20"Yeah, there are some bubbles."
0:56:20 > 0:56:24We were flying with the drone and we could see dolphins,
0:56:24 > 0:56:28and while they thought they could only see one dolphin, we saw five.
0:56:28 > 0:56:30And they had no idea.
0:56:30 > 0:56:34The crew are surprised to find these dolphins aren't solitary,
0:56:34 > 0:56:36but come together to hunt as a team.
0:56:36 > 0:56:40You're starting to see stuff with the drone that you suddenly go,
0:56:40 > 0:56:42"I thought there was one dolphin there," and
0:56:42 > 0:56:46then you count that there are five and then you're looking in one place
0:56:46 > 0:56:48and they're all behind you, laughing at you.
0:56:48 > 0:56:52This new perspective has given the crew a first glimpse
0:56:52 > 0:56:54into a mysterious jungle animal
0:56:54 > 0:56:57in one of the least-known corners of the Earth.
0:57:06 > 0:57:10Next time - a land of extremes that pushes life to the limit.
0:57:13 > 0:57:16Animals have extraordinary ways of dealing with the hostile conditions.
0:57:18 > 0:57:22Creating the most epic survival stories on Earth.
0:57:22 > 0:57:24These are deserts.