Wild South America (2000–…): Season 1, Episode 2 - Episode #1.2 - full transcript

The Amazon is the mightiest river
on earth.

A thousand miles
before it reaches the sea

its main channel is already
ten miles wide.

By the time it meets the ocean

it carries a fifth of all the river water
in the world

spilling an incredible forty five million
gallons a second into the Atlantic.

Every year, without fail
the Amazon bursts its banks

and floods an area of forest
the size of England.

This huge change in water level

over such a vast area

affects everything that lives here
in a dramatic way.



Over its four thousand mile course
from the Andes to the Atlantic

the Amazon is swollen
by some eleven hundred tributaries.

Several are massive rivers
in their own right.

Between them they drain
forty percent of the continent.

Three thousand kinds of fish
live in this waterworld.

And where there are fish
there are fish hunters.

Giant otters.

They really are giants nearly two metres
from nose to tail.

Local people call them 'Iobos del rio'
wolves of the river.

They live almost entirely on fish

though they can kill caiman
and anacondas.

They're one of the top predators
of the Amazon

the aquatic equivalent of the jaguar.

Most otters are solitary
but these are very sociable.



They live in family groups
of about half a dozen

a mated pair and their full grown young
from previous years.

The otters bridge two worlds.

All their food comes
from the river

but they sleep
and rear their cubs on dry land.

So their lives are profoundly affected
by the changing level of the river

which has its origins far to the west

in the distant peaks of the Andes.

After a first precipitous rush
from the mountains

the river's course is flat and winding.

For the next three
and a half thousand miles

it drops barely two inches a mile.

As sluggish meanders twist
across the floodplain

their course is constantly changing

creating new channels and lakes.

This is more than just a river

it's a whole river system.

It's October
the height of the dry season.

The Amazon is at its lowest ebb

and showing its bare bones.

For just a few weeks each year

sandbanks rise clear of the water

giving a brief window of opportunity

for one of the Amazon's
most remarkable animals.

Giant river turtles.

They're one of the largest fresh water
turtles in the world

over a metre long
and weighing more than forty kilos.

They come back to the same place
each year to lay their eggs.

But this is a race against time

because the sandbanks will soon
be flooded again.

For two weeks after they arrive

the pregnant females bask in the sun.

This hastens the development
of the eggs

still inside their bodies.

When she's ready

each huge female digs a hole
a metre deep.

In it she'll lay a hundred
soft-shelled eggs.

But all this activity
doesn't go unnoticed.

Good sandbanks are few and far between

so early clutches of eggs
are often accidentally dug up

by turtles nesting later.

For the vultures too
this is a once a year opportunity.

But it only lasts a few days.

The turtles will soon be gone.

In forty five days
the surviving eggs will hatch

far quicker than other turtles.

Just a week or two later

the sandbanks will be drowned again.

If the rivers rise early
all the eggs are lost.

At the peak of the dry season

broad reaches of river
can be almost cut off

as sandbars separate them
from the main flow.

Fish become concentrated
in these lagoons

so for predators
the killing is easy.

Caiman and egrets gather to take advantage
of the best hunting of the year.

The fish take shelter in the reeds

but in shallow water
they're easier to catch.

Striking low and from the side
makes it harder

for the egrets' prey to see them
until it's too late.

Sometimes the caiman seem
to work together

to herd fish into the shallows.

The shoals of prey become
even more concentrated.

The water literally heaves with fish.

With so many to choose from

there's no need to single out a target.

A random lunge can be just
as effective

and as each caiman strikes

it panics fish into the jaws of another.

But the good times won't last long.

The caiman must make the most of them
while they can.

A feast like this could keep them
going for months.

For most fish
the dry season is not a good time.

They're on everyone's menu

and their own food's so scarce
that many will not eat for months.

Some of the birds are
having a hard time too.

Tui parakeets are seed eaters

and the seeds of this munguba tree
are a rare treat

The munguba uses the wind
to scatter its seeds.

Each one is carried on
a parachute of fluff

but if it lands in the water

there's not much chance
of it germinating.

These are Brycon
sometimes called South American trout.

They're so hungry

they jump at the chance of
even these meagre mouthfuls.

They can leap up to four times
their body length.

Even at low water
the larger rivers are still navigable.

On the Amazon's main channel

seagoing ships can reach
as far as the city of lquitos

over two thousand miles from the ocean.

The rivers are the main arteries
of travel.

Local people depend on them
throughout the year.

Riverside communities rely heavily on fish
for their livelihood.

For the people
as for the natural predators

low water is also the best time
to make a catch.

Laden with silt
from the distant mountains

the rivers are often very muddy.

It's hard to see much under water
during the day

At night, the problem is even worse.

Infra-red cameras let us
follow the action in total darkness.

But how do the fish find their way?

Some, like these Candiru
have an acute sense of smell.

They can detect the slightest
trace of blood or decay.

Fish trapped in fishermen's nets
are easy meat.

Like aquatic vultures

the Candiru home in
on the scent of flesh

and strip the carcass from within.

A close relative of these Candiru
has the most unsavoury reputation

of any fish in the Amazon.

It's a parasite rather than a scavenger

and it's attracted to blood and urine.

It's been known to swim right up
into people's bodies

wedging itself inside
with backward-pointing spines.

Other fish deploy much stranger senses

...ones that we can scarcely
begin to visualise.

They generate an electric field
around their body.

Any object in their path
distorts the field.

They detect the changes
with receptors in their skin.

This extraordinary sense allows them
to find their way

around in the murkiest of water

and to detect and catch their prey.

They also use it to communicate.

Most electric fish generate
a very weak field

but not this one.

To local people

it's one of the most feared fish
in the Amazon

the electric eel.

Its two metre long body
is a gigantic battery.

It can deliver a jolt of six hundred volts
a shocking defence

enough to kill a child

and more than enough to
stun its prey.

As the rivers shrink to
their very lowest

some of the channels are
entirely cut off.

Here, predators and prey become
even more concentrated.

Territorial male caiman have
put aside their differences

to take advantage of the glut of food

but in such cramped conditions
disputes are inevitable.

Despite the crowds

there are still plenty of fish
to go round.

But that doesn't remove the temptation
to steal someone else's.

Even theft is scarcely worth
the energy.

The heron keeps its meal.

For fish hunters
these are the good times

though not without their annoyances.

Caiman may look armour plated

but there are chinks
in their defences.

With only their heads out of water

they're still a target for
blood-sucking horseflies.

Even a harmless butterfly
can be a nuisance.

The first showers hint
at a change of season

a promise of rising water

and better times to come
for fish now

trapped at the mercy of predators
like caiman and egret

For the cormorants too

the best of the fishing
will soon be over.

Released from
their dry season prison

the fish will spread out
and become harder to catch.

They'll be too scattered to
feed a flock like this.

The dry season may be coming to an end
but not just yet.

This is only an isolated shower.

It will take much more to
set the fish free.

The first rain can even make things worse
for them... much worse.

The cold rainwater sinks

displacing warmer
and less oxygenated water below.

Decaying vegetation and bubbles of
hydrogen sulphide rise from the depths.

This lethal cocktail
makes oxygen levels plummet

and fish are soon gasping for breath

The topmost film of water
where it touches the air

still has the most oxygen

so desperate fish skim the surface
to avoid suffocation.

Most kinds of fish seem to be affected.

For the birds

this may be the last opportunity
to make a killing.

The distressed fish are easy prey
for the cormorants and egrets.

With so much on the menu
they ignore the dead and dying

but not all of these will go to waste.

For the vultures

this is another brief window
of opportunity.

Fish kills are sudden and short-lived
and the dead fish soon sink.

Black vultures
have an acute sense of smell.

The stench of rotting fish draws them
to the feast in increasing numbers.

There is too much
even for the vultures.

The victims of this natural disaster
can number tens of thousands.

Isolated local showers
turn to more general rain.

The Amazon basin gets a massive
three metres of rain a year

most of it concentrated
in just a few months.

The timing of the rainy season varies

from one part of
this vast catchment to another

but the result is the same everywhere

a slow but inexorable
rise in the river level.

The changing season has a profound
effect on everything that lives here.

Swollen by the rain that falls
within the basin

the rivers are soon full to the brim.

But there's more to come.

In the cloud forests of the Andes

the annual rainfall can be
an incredible six metres.

When that joins with snowmelt
from the high peaks

the results are dramatic.

It may be days or even weeks
before these torrents

make their full impact
on the floodplain forest

hundreds of miles to the east.

But already, animals are on the move.

The rain that has already fallen
here waterlogs the soil

and raises the humidity

and that triggers
a remarkable migration.

The small creatures of the leaf litter
move upwards, into the trees.

Soon, their world will be transformed.

But up in the treetops
predators are waiting for them.

For many of the leaf litter animals

the shift to the treetops proves fatal.

So why do they move?

It can take two months

but finally the rain and snowmelt
from the Andes make their mark.

The rivers are already full
from rain in the lowlands

and can take no more.

Now they overflow into the forest.

The reason for that mass migration
from the leaf litter becomes clear.

The forest floods to
a depth of ten metres.

The flood changes the lives
of everything

that lives here.

Even the giant otters
are on the move.

Their dry season dens
are now underwater

so they have to move their young
to higher ground.

This year's cubs are still
too small to swim far

so the adults carry them
in their jaws.

Giant otters are territorial

and the group's range has to include dens
for both low and high water.

The whole family share the task of
looking after the young.

It will be two or three years
before their elder brothers

and sisters leave to start
a family of their own.

Few predators will
tackle a full grown giant otter

but infants can be killed
especially by caiman.

Safely installed in their new home

the otters will stay here
until the floodwater recedes.

At the height of the flood

Amazonia is transformed.

An entirely new habitat
has been created

a waterworld that can drown
the forest

for ten miles either side
of the main river channel.

At the peak of this inundation

the rivers engulf an incredible fifty
seven thousand square miles of forest

an area the size of England.

The trees can stand in water
for six months or more.

But this drowning is something
that happens every year

and many will turn the flood
to their advantage.

Branches where birds once perched
now shelter fish.

Freed from the dry season confines
of the riverbed

they spread out into the forest.

This is their season of plenty.

Predators follow the fish
into the forest

but now it's much harder
for them to hunt.

Their prey are more scattered

and have more places to hide.

The hunters include one of the Amazon's
most remarkable animals.

The Boto dolphin.

This river dolphin is almost blind

but the water here is often so muddy
that eyes are useless.

It finds its way through the branches
by using sonar.

Unlike its marine relatives it
has a very flexible neck

so it can sweep its head from side
to side to scan the water ahead

and to catch fish.

Because there is so much
decaying vegetation

the water in the flooded forest
is very low in oxygen.

That's no problem
for an air-breathing dolphin

but how do fish survive here?

The Pirarucu is the largest
freshwater fish in the world.

It can grow to three metres

and weigh nearly a hundred
and fifty kilos.

Like the dolphin
this giant has to breathe air.

Every few minutes

it comes to the surface
and takes a gulp of oxygen.

All sorts of other fish
share this ability.

The electric eel absorbs oxygen
through the lining of its mouth.

It acts like a lung.

Many of the Amazon's fish have a high
concentration of red blood cells

which makes their gills more effective

but they also take air
from the surface.

A swamp eel traps great gulps of air
in its inflated throat.

Animals that live in the trees

also need special skills to survive
in the flooded forest

like being able to swim.

Sloth and spider may seem
unlikely swimmers

but their own form of freestyle
is now the best way

for them to move between trees.

If you can't swim, climb or fly
you can't stay here

so this waterworld has none
of the usual forest animals

like deer or peccaries.

The sloth may not be fast

but it's a good swimmer
and climber.

The most unexpected creatures
take to the water.

Fire ants even turn the flood
to their advantage.

When their forest floor nests
are drowned

they set sail on a living raft

formed from their own
inter-linked bodies.

Drifting with the current

they can end up far away
from their old home.

All they need for a new colony
is on the raft

including the next generation.

But the voyage has its hazards.

Fire ants have a painful sting

but that doesn't stop fish
picking them off

as they drift through the forest.

Eventually the rafting ants
make landfall.

This tree will provide a refuge
until the waters fall

and they can return
once more to the forest floor.

If their eggs are to survive

they must find shelter
from the drying heat of the sun.

A crack in the bark
is a perfect nest site

and the tree comes
with a built-in food supply.

Others have already taken refuge here.

They arrived even before
the flood had started.

The lizard has now got competition.

These insects are all
on the fire ant menu

but they seem strangely reluctant to jump.

Those that do take the
plunge may find

that they've leapt
from the frying pan into the fire.

Fish are quick to
take advantage of any insects

that fall into the water.

For some, like the metre-Iong Aruana

they're a large part of their diet.

The fish may not
have eaten for months

so now it's time to fatten up.

Wind and rain dislodge
a steady supply of insects

from the crowded canopy above.

Even if it's not
actually in the water

an insect still may not be safe.

All sorts of other fish
make the most of the windfalls.

Needle fish cruise the surface
picking off anything small.

Like some other fish in the Amazon

and the dolphins
these little fish have a marine origin.

They spend most of their time
near the water surface

hunting by sight.

That slim profile may help to
camouflage them.

Their long 'beak' is ideal
for seizing prey.

The rising water triggers an event

that will affect the lives of almost
everything that lives here.

It's now that the trees
in the flooded forest fruit.

Many trees depend on the flood to
disperse their seeds.

By the time they germinate

the water will have carried them
far away from their parent tree.

But drifting with the flow isn't
the only way seeds can travel.

In this strange new world

some trees use fish
to scatter their seed.

The fish eat the fleshy
part of the fruit

but the hard seeds pass
through their gut unharmed.

This is a good time for fish.

They gather wherever fruit falls.

And where there are fish
there are fishers.

Most of the predatory birds have gone

but not this one
a little green heron.

Most fruit-eaters have an equal
partnership with the trees.

They spread their seeds
in return for food.

But some fish don't play
by the rules.

They eat the seeds

crunching them up and destroying
rather than dispersing them.

Tambaqui have a powerful sense of smell
to lead them to fruiting trees.

They have powerful jaws, too

well able to crush hard seeds
such as this walnut-like supacaio.

Little of what they eat will
ever get the chance to germinate.

The flood is also a good time
for the Uakari.

These monkeys live in loose
groups of thirty to fifty.

They seldom come down to the ground

preferring to travel through the treetops
in elegant leaps and bounds.

So when the forest floods

they have no need to swim.

These bizarre monkeys live
only in floodplain forests

where they take full advantage
of the flush of new fruit.

Local people call this
'the English monkey'.

Its red face reminds them
of a gin-swilling white man

who's been out too long in the sun.

In fact
the red face is a sexual signal

a sign of potency and good health.

Uakaris are one of the few monkeys

that live in this riverine forest
all year round

surviving on leaves and unripe fruit.

With their strong jaws

they can tackle food
that would be too tough for other animals.

The seasonal flooding of the forest
leaves nothing untouched.

Everything that lives here has to adapt...
or move on.

Remarkably
people stay here right through the year.

Their houses are built on stilts
or rafts

to raise them above the flood

as are their chicken coups.

Watering the plants may be easy

but a floating platform is now the
only place to grow vegetables.

This is a challenging time.

Most people depend on fish

but the shoals of the dry season
are scattered through the forest

and so harder to catch.

All sorts of predator
are having a hard time.

Even fearsome hunters like piranhas are
reduced to scavenging for scraps.

Of all the Amazon's fish

these have the most notorious reputation.

They could strip a chicken to
the bone in seconds

if it were careless
enough to fall in.

Living on the water
does have some advantages

at least for children

though most of us wouldn't

want piranhas in our swimming pool.

In fact

their ferocious reputation
is undeserved.

Only in the dry season

when they're concentrated
in landlocked pools

are they truly dangerous

So for now it's safe to swim.

People can live without dry land

at least for a while
but otters can't.

They need a dry den to sleep in
and rear their young.

They're now
deep in the flooded forest

well away from the open river

hunting fish hidden in the trees.

The easy times of the dry season
may have gone

but otters are supreme predators.

Their webbed feet and paddle-like tails

their strength and agility make them a
match for even the most elusive fish.

If fish are hard pressed to
escape an otter hunting alone

they're even less able to get away
when they hunt as a pack.

Often the whole family fishes together

driving their prey into a tight shoal

or trapping them against a bank.

The rewards of communal fishing

are one of the most important benefits
of family life.

Over the months to come

the floodwater will slowly drain
from the forest.

The rivers will once again
be confined to their channels

and the otters will return to
their dry season dens.

Giant otters are an indicator
of a healthy river.

Only where they have a plentiful
supply of fish

and can live undisturbed do
they survive.

There are many threats to the world's
last wild places

but the sheer scale of the Amazon
could be its salvation.

It's far too mighty to control
dam, or divert.

The massive yearly flood
makes it a hostile home

for all but a few people

and means this watery wilderness
may always remain untamed.