Original subtitles

The Amazon, the greatest rain forest on Earth.

It is home for one in 10 of all species.

It may look like a vast, tropical paradise,

but nothing could be further from the truth.

This is a landscape that is as much water as wood.

And each year, the two worlds collide

when the forest fills with water.

The Amazon is inconceivably vast.

It covers an area of almost 3 1/2 million square kilometers.

It is not a uniform landscape, but many,

from lowland flood forest to upland forests on dry ground.

Within this green space, a huge number of animals

strive to make a living.

Each morning, howler monkeys greet the day.

They're advertising their ownership

of a patch of forest.

But their calls alert a keen-eyed killer.

The harpy eagle is the most powerful

bird of prey in the world,

quite capable of carrying off a howler monkey.

The harpy's wings are broad and rounded,

which allow it to maneuver through the canopy

with deadly precision.

The harpy's legs are as thick as a mans' wrist,

and it has the largest talons of any eagle.

It can carry off prey the same weight as itself.

But this time, the giant eagle's objective

was only a branch.

The leaves are for the nest,

which is in one of the tallest trees in the rain forest.

The fresh twigs may not be there to build up

or decorate the nest.

The leaves of many plants in this forest

contain chemicals, poisons,

to stop animals eating them.

And these leaves may act as an insect repellent.

The eagles could be deploying chemical weapons.

The uniform green of the Amazon hides many differences.

There are terra firme forests on high ground

and flood forests alongside the myriad rivers and lakes.

Many of the trees are engaged in a hidden war,

where they use chemicals for protection,

something the woolly monkeys might wish for,

especially from insects.

When not scratching, the monkeys provide

a service to the trees.

Figs offer nutritious, soft fruits

full of small seeds.

As they feed, the woolly monkeys pass the seeds

and so spread fig trees through the forest.

In the unseen war, the trees fight to keep their leaves.

Many use poisons to stop animals eating them,

but at the same time, encouraging creatures

to eat their fruits.

Most fruit is highly nutritious,

and this has helped shape the sex lives of one resident,

the cock-of-the-rock.

Each morning, after quickly filling up on fruit,

the fabulously-colored males

gather at a communal display area, a lek.

Each male owns a low-level perch,

and below it a small patch of ground.

It is because they are fueled by fruit

that the males can spend most of the day displaying.

The males compete amongst themselves,

trying to drive other males from their perches.

The arrival of a plain-colored female,

and the males descend to their individual areas.

Curiously, the males now stop calling

and hardly move.

They wait with all their feathers pumped up,

hoping the female will visit their patch.

Males try to disrupt each other's displays,

barging into the scene mid-action.

The female watches and assesses the quality

of the males on offer.

The males use patches of sunlight

to heighten their splendor.

She has chosen a male on the far edge of the lek,

where mating discreetly takes place.

The trees offer edible fruit

as a reward to animals that spread their seeds,

but many put up a chemical shield

to defend their leaves from being eaten.

There's an unseen war between the trees and leaf-eaters,

and the most important consumer of leaves in the Amazon

is this small insect,

the leafcutter ant.

Its jaws vibrate a thousand times a second

as it slices through leaves.

The cut leaves are not eaten by the worker ants

for they may be toxic.

Instead, the ants carry them back to the nest.

As they travel, the ants lay down a scent trail

to mark the way.

The chemical, a pheromone, is so powerful

that each ant produces only one-billionth of a gram.

The cut leaf can weigh 20 times the ant's own weight,

the equivalent of us carrying a one-ton load.

More remarkable still, these mini-Hercules

range more than a hundred meters from their nest,

the human equivalent of a 25-kilometer hike.

As if the load were not enough,

smaller ants ride on the leaf, shotgun style,

to protect the carrier from parasitic flies.

And flies are not the only danger.

There is a fungus that enters an ant's body,

eats it, then grows its own mushroom from the dead ant,

to spread its spores to yet more ants.

The underground nest is huge,

and may house as many as eight million individuals.

The leaves are taken to special chambers

where a different class of ant

cuts them into smaller pieces.

The purpose of all this industry is to feed a fungus.

The ants are farmers, and the smallest kind of worker

tends the fungus gardens.

This is the food for the colony.

The ants and the fungus depend totally on each other.

If the ants bring leaves that contain chemicals

that upset the fungus, somehow it tells the ants

and they then gather different leaves.

The queen is a colossus in this Lilliputian world,

and weighs 1,500 times more than the small gardener ants.

Only she produces the eggs that will turn into

the many kinds of workers.

The colony is always busy,

digging new chambers to grow more fungus.

The spoil is brought out and dumped.

The ants have found one method of dealing with toxic leaves.

Other animals have found different ways

to overcome this challenge.

The mother sloth has her own way of finding edible leaves,

very slowly.

The reason for the sloth's famous lethargy

is that leaves have little nutritional value,

so the sloth saves energy by a very low,

slow metabolism.

The sloth uses her fine sense of smell

to find leaves with little or no poisons,

and the baby learns from its mother.

Movement is a real giveaway to a predator,

but this is no problem for the sloth,

which rests and sleeps for much of the day.

There is excitement at the nest.

The eagle chick has hatched.

The mother will do most of the nest duties,

shading the baby from the fierce, tropical sun.

The chick will spend five months in the nest

as it grows to the size of its giant parents.

In all that time, they will bring in branches

as insect repellent.

The mother sees something move.

It's not the sloth, but a howler monkey.

The monkey will be one of many

that the parents bring to their single chick

over the coming months.

Only the largest trees in the forest

can support the eagle's huge nest.

And one of the bird's favorites

is the Brazil nut tree.

It is a forest giant, and its fruits too are huge.

The fruit weighs over two kilos,

and as the tree can grow to 50 meters,

it has a long way to fall.

There's even a record of a fruit

hitting and killing someone.

The fruit is immensely hard,

and for a long time it was a mystery

as to what animal could open it.

But we know now that this rodent, the agouti,

both eats the Brazil nuts

and helps produce new trees.

The agouti's sharp incisors and powerful jaws

chip away at the case.

But it takes a lot of patience and stamina

before the rodent reaches the nuts inside.

The agouti eats some and buries the rest for later.

Luckily for the tree, the agouti doesn't remember

where all its buried treasure lies,

and so in the agouti, the Brazil nut tree

has a well-paid gardener that even plants its seeds.

The large seeds can lie dormant for over a year

before they germinate.

And the story doesn't end there,

for there is another animal that relies

on the Brazil nut fruit.

This is a kind of poison dart frog.

The frog gets its toxins from the ants and mites it eats,

which in turn get the poisons from the leaves.

The frog concentrates the poison

and advertises the fact with its bright colors.

The female frog lays her eggs on the damp forest floor.

The male guards them and keeps them clean.

When they hatch, he gives them a lift.

The tadpoles stick to the mucus on the frog's back.

The frog carries the tadpoles, one by one,

to empty Brazil nut cases.

He checks the miniature pond

to see that it has enough food for the tadpole to eat.

In a couple of months, young poison dart frogs

will emerge from the safe nurseries

of the Brazil nut cases.

The Amazon forest is a tough place to live.

No paradise, it is full of hidden poisons

and unpalatable plants that its inhabitants

have to cope with.

The howler monkeys must rest and sleep for hours

whilst they digest barely edible leaves.

The night brings new challenges

and a different cast of animals,

creatures that tuck away out of sight during the day.

And there are different fruits to be found and consumed.

The four-eyed opossum prepares for the night.

It's an omnivore, a generalist.

It uses its sense of smell to find food

in its dark world.

But it has to compete with bats.

A large fruit is an irresistible attraction.

The four-eyed opossum needs to move quickly

if it's to fend off the hungry bats.

They are absorbed with feeding,

but they must be wary of the opossum.

The allure of so much fallen fruit is too much,

and once the opossum has left, the bats return.

They are in the grip of a feeding frenzy,

and fail to notice the opossum's return.

The Amazon is a world where much is hidden,

where the trees offer fruits whilst defending their leaves,

a world of poisons, where plants and animals

fight an unseen war.

But for both plants and animals,

there is one huge challenge,

the weather.

The Amazon is a rain forest.

As much as 2 1/2 meters of rain falls a year,

and most is concentrated in the wet season.

The trees and their leaves

play a crucial role in the weather,

for half the rain that falls

comes from the forest itself.

The leaves naturally release water vapor,

which then forms clouds that returns as rain.

The downpours are dangerous for the harpy eagle chick.

If the baby is drenched, it will chill and die.

These are perilous times

for the most powerful eagle on Earth.

The rains transform the Amazon forest

and its many rivers.

The water swells the rivers, and as they rise

they begin to enter the forest.

The rainstorms are so intense

that the forest becomes an amphibious world,

halfway between air and water.

The leafcutter ants are in trouble.

Their pheromone trails are washing away.

The ants are disoriented.

Their highly organized world is disintegrating

under the onslaught of the rain.

And things are about to get even worse.

It's not just the torrents of water from above,

the rivers keep rising, overwhelming the ants' trails.

The ants, the greatest harvesters of leaves in the forest,

are swamped by the rainy season.

As the water rises, it spreads into the forest

and creates some of the most unique habitats in the world,

the Varzeas and Igapos,

or seasonally flooded forests.

Almost a quarter of a million square kilometers of forest,

an area three times the size of Austria, is submerged.

The transformation is total.

Where once birds perched and agoutis fed,

there are now new opportunities.

At its peak, the flood can reach

over 20 kilometers into the forest.

The water is green with microscopic plankton,

which feeds schools of small fish

as they move into the flooded forest.

The fish set up home amongst the leaves

of the forest floor, where ants once carried

their heavy loads.

This male rivulus is attracted by a female.

She is larger and sends out strong come hither signals.

But all is not as it seems.

The male is enticed, but he is courting with death.

The female was nothing of the sort,

but another species, erithrynus,

a fishy femme fatale that mimics a female

and so lures the male to its death.

As the water rises further into the forest,

larger predators move in with it.

The mata mata lives on the front line

as the flood pushes into the trees.

It has its own method for catching fish.

Its technique is to blend into the background.

It looks like an old weed-covered log.

Its disguise is so complete

that fish nibble its shell.

This formidable predator's only limitation

is that it must breathe air.

This restricts the mata mata to the shallow edges

of the encroaching flood.

The turtle settles down again

and waits,

and then explodes into action.

For most fish, the end is as unexpected

as it is sudden.

The Brazilian name mata mata may refer to

the turtle's ability to kill.

If so, it is highly appropriate.

As the water fills the forest,

it causes problems for some of its slower inhabitants.

The sloth faces the new challenge of moving

from tree to tree as it searches

for the least poisonous leaves.

The sloth is a surprisingly good swimmer,

which is just as well.

Mother and baby can swim

very slowly

the short distances between trees,

as long as their fur doesn't become too water-logged.

Curiously, the sloth's wet fur

may be a blessing in disguise,

for it encourages green algae to grow,

which provides a kind of camouflage.

As the water continues rising up the branches of the trees,

a male splashing characin moves in

and sets up territory,

and it soon attracts a female.

The male guards an anonymous patch of water

below a twig.

The splashing characins are unique among all fish

in laying their eggs on leaves above the water.

The act of mating requires extraordinary coordination

and perfect timing.

The reason for all this precision

is that the fish's eggs are safer on a leaf

out of the water, away from hungry mouths.

Once all the eggs are laid,

the male not only guards them,

he also keeps them moist.

The eggs develop quickly,

and after two days, the babies are ready to hatch.

They drop safely into the waters of the flooded forest.

The water continues to rise.

In the Amazon, it rains over 200 days a year.

All the animals of the forest

have to live with the wet.

The leafcutter ants are severely handicapped by the rains,

but their vast underground colony

is in the terra firme forest, safe from flooding.

Even when the rains stop the ants gathering leaves,

they have their fungus gardens to feed them.

Rain or no rain, there is always work to do.

The smallest type of ant, the minion,

looks after the eggs and feeds the larvae.

But the underground city is vast.

There may be as many as 1,000 chambers,

all tended by gardener ants,

and producing fungus for the colony.

The ants, with their intricate relationship with the fungus,

have found a way past the chemical defenses of the trees.

The agouti stays on higher ground,

close to the Brazil nut trees and its buried food supplies.

The cock-of-the-rock too live on the higher ground.

The males display all year round,

even in the rainy season.

The males take exception to the agouti

wandering through their display ground.

Like the cock-of-the-rock,

the woolly monkeys prefer to eat fruit,

but it's not always available.

In tough times, the monkeys select the youngest leaves,

for they're likely to be the least poisonous.

Yet some trees fruit at this time,

when they're surrounded by hectares of water.

The rubber tree seeds seem to be wasted,

falling into the floods.

But nothing could be further from the truth.

This fish, the tambaqui,

swims below the rubber tree.

It has evolved as a specialized fruit and seed eater,

with powerful jaws and teeth that can crush

the hardest seeds.

The strange relationship between fish and tree

is mutually beneficial,

for the tambaqui doesn't crush all the seeds.

Those that pass through its gut

are spread throughout the flooded forest.

At the height of the flood,

the Varzea is not a safe place,

for the pirarucu, the largest fish in the Amazon

prowls its deep waters.

This monster can grow up to three meters long.

The pirarucu is a strange giant,

for the fish rises to the surface

every 10 to 15 minutes as it hunts,

for it must breathe air.

The pirarucu is a member of a primitive family of fishes

that has been stalking and terrifying other fish

since the age of the dinosaurs.

And the pirarucu has a relative,

another dinosaur fish that haunts the leafy,

sub-aquatic world of the flooded forest.

It has a very different target,

the small creatures that are stranded

on the trunks and branches of the flooded trees.

At one meter long, the arowana is smaller

than the pirarucu, but no less frightening.

The flood brings it closer to the treetops

and its prey.

The floods are a time of plenty for the arowanas.

For months they have access to the trees.

But all good things must come to an end.

The waters begin to recede.

This is a dangerous time for the fishes of the forest.

It is all to easy to be trapped in pools and puddles,

stranded, as day after day, night after night,

the forest dries out.

Many fish suffer this fate, but in the Amazon,

one animal's misfortune is another's opportunity.

The four-eyed opossum takes the chance

to add yet another item to its varied diet.

But not all the fish are helpless.

As the pools empty, erythrinus, the killer mimic,

simply swims over the ground.

Gravity carries it downhill to the river.

In this remarkable way, it escapes certain death.

Rivulus too has an escape strategy.

It uses its powerful tail muscles

to launch itself into the air.

In this strenuous way, it flips over the forest floor,

eventually arriving at permanent water.

The temporary inhabitants of the flooded forests

are forced back towards the streams, rivers and lakes.

The pirarucu father guards his babies.

They hatched as the waters rose,

and have grown rapidly in the flooded forest.

Now the monster fish shows his gentle side,

watching over hundreds of his babies.

They've already taken up the habit of breathing air,

and that ability is crucial for babies and adult alike,

for the warm waters have very low oxygen.

The babies will stay with their father for three months.

The male secretes a pheromone from his head,

which keeps the young fish close.

They will grow to one meter long mini-monsters

by the time they are one year old.

Few of these babies will reach adulthood,

but those that do will become

the largest freshwater fishes in South America,

and terrors of the flooded forest.

The ebb and flow of the floods

brings both feast and famine to fishes,

and the rainy and dry seasons affect

all the creatures of the Amazon.

It's in the dry season, in the terra firme forest

that another giant of the Amazon reaches a key moment

in its parental duties.

The harpy eagle brings her last meal to the nest.

It's five months old, and almost fully grown.

Over the long period in the nest,

its parents have brought monkeys and sloths,

placed leaves to fend off insects,

and protected it from the rains.

Now it's time to take to the air.

But first the chick must strengthen its wing muscles.

The realm of the harpy eagle

is one of the most complex in the world.

The trees hold the key to many of its secrets.

They guard their precious leaves with poisons,

and those same leaves release the water vapor

that in turn, produces the clouds

that feed the most remarkable floods on Earth.