Nestled in the northeastern corner of Argentina...
the Iberá wetlands.
This is a diverse water world teeming with wildlife...
hundreds of animal species,
and over 1,000 different plants flourish in this tropical Eden.
But this strange paradise is not without its perils.
Stalking the shadows of the river boughs,
and lurking beneath the surface of the tranquil waters,
hidden killers lie in wait.
Above the hunters, monkeys haunt pockets of forest...
giant birds adorn the tops of the trees,
and the smallest creatures glitter and dance.
But even in Eden, beauty can be deceiving.
The Iberá wetlands of northern Argentina
are still one of Earth's secret wonders.
Secluded swamps...
grassy marshes...
and deep sunlit lagoons...
spill out across 13,000 square kilometers.
Such an expanse, that this kingdom of water
covers an area over 16 times the size of New York City.
Long, hot sunny days
make Iberá a riot of vibrant colors.
In the language of Iberá's first inhabitants,
ts name means brilliant waters.
And it's easy to see why.
Over 20% of Argentina's biodiversity
can be found in this patch of paradise.
Underneath the glassy waters and sandy soils
s one of the most important freshwater reservoirs
on the continent.
In rare periods of drought, the reservoir feeds the wetlands...
ensuring the leaves never brown and the flowers never wilt.
But not all is as it seems in this water wonderland.
Amongst the color,
the wetlands' most dangerous residents are hard to find.
But as the dry season nears its peak,
stifling humidity heralds their sudden appearance.
It's July.
At this time of year, the water level of the wetlands
s at its lowest.
The stagnant pools have shrunk,
and grown warm in the daily 30-degree heat.
In the middle of the day, Iberá is quiet.
All of the wetland wildlife seeks silence and shade.
Except for one resident.
Yacare caiman, a member of the crocodilian family,
have been forced together by the ever-dwindling pools.
Though these caiman are relatively small for their species,
with males averaging over two meters long...
t's still an uncomfortable crush...
and tensions are running high.
It's now that the normally silent inhabitants of these water worlds
draw attention to themselves.
A female senses her moment...
and with a grunt indicates her presence to the males around her.
Initiating a strange ritual.
Lifting his head and arching his tail,
this male inflates his throat.
And the water dances with an infrasonic boom.
Other males respond in turn.
This mysterious ceremony is thought to indicate strength.
Only the toughest will earn the right to father the next generation.
For a creature so often the villain of the wetlands,
this is an oddly democratic way to assert one's authority.
As the water falls still once again,
the hierarchy has been established.
When the dry season draws to a close,
this female will know who to mate with.
But while the water levels are low,
there are more pressing matters at hand.
It isn't only the caiman who have been marooned by the shallows.
Fish, too, flounder in the warm waters.
As vegetation in the water rots, it consumes oxygen,
stagnating and starving the small pools.
It's now that the wetland gives up its treasure.
In their desperation for oxygen,
fish are driven to the surface of the water...
nto hungry beaks.
Over 300 different species of wetland birds are waiting for them.
Herons, storks and egrets share the bounty...
wading their way through the shallows easily picking off victims.
In the Iberá wetlands of Argentina, isolated in a tree-top fortress,
hides a bird so large and so strange
that it appears to be from the age of dinosaurs.
This is a jabiru,
the tallest flying bird in South America,
standing at around one-and-a-half meters.
Despite their colossal size, these are shy animals,
and raise their chicks in relative privacy.
Their name means swollen neck.
This band of brightly colored skin
acts as indicator for the jabiru's mood.
The more scarlet the coloration, the more irritated the bird.
Despite their shyness,
they won't hesitate to aggressively defend their nest.
It will be another two months before the chicks are really to fledge.
By then they will be almost fully grown.
Life in a jabiru nest can get very crowded.
If the nest wasn't already busy enough,
monk parakeets have moved in underneath...
and seem intent on undoing the jabiru's construction.
They make for extremely noisy neighbors.
It's a smart move for the parakeets.
The jabiru will fend off any potential predator
from their nests, too.
Others haven't been so lucky.
This lone male parakeet has just returned
to find his nest totally devastated.
It becomes clear who the culprit is.
A caracara is enjoying a post-meal preen.
The normally busy home is empty.
His whole family are gone.
But there isn't time to mourn.
Dark clouds are gathering.
As October approaches,
huge electrical storms appear on the horizon.
The rainy season has arrived.
Rivers swell, and burst over floodplains.
As much as 20 centimeters falls in the space of 24 hours.
The wildlife of the wetlands takes cover.
In the weeks that follow the downpour,
Iberá's marshes and lagoons become a riot of color.
Water hibiscus envelops the wetlands with purple blooms...
and dry yellow grasses flush green.
In November, with the wetlands finally refreshed by the rains,
Iberá becomes a hive of activity.
The rainy season sparks a baby boom in the wetlands.
It's the busiest time of year for the largest rodent in the world.
Capybara.
These water beasts can weigh up to 79 kilos.
They're well adapted to an aquatic existence.
Their body density is only slightly higher than water,
giving them perfect buoyancy...
and partially webbed feet make them incredible swimmers.
A capybara's eyes, ears and nostrils
are also positioned high on their heads,
so they can stay submerged as long as they want.
Normally, they're pretty lazy creatures,
but the rains ignite a sudden burst of energy.
Capybara aren't fussy when it comes to choosing a mate.
Males and females will mate with numerous partners.
But the females don't just give it up.
The attention of a male isn't always welcome.
Fortune hasn't been kind to this male.
He's smaller than most...
but, luckily, for a capybara,
t's all about being in the right place at the right time.
But it doesn't mean the female is going to make it easy for him.
The thrill is in the chase.
These games could go on all day...
but he's determined to win her over.
When he finally catches up...
the reward is brief.
In 150 days, she'll give birth to his legacy...
and if he's really lucky, so will many others.
In Argentina there's a baby boom
for the largest rodent in the world,
the capybara.
In Iberá's capybara society,
the responsibilities of parenting
are shared amongst other females in the group.
Most mothers seem neither to know nor care which baby is her own.
But the young capybara learn fast.
They learn to graze after one week...
are fully weaned at three months...
and travel in groups together for safety.
But they get tired very easily at this age,
which makes them vulnerable.
Life is perilous for a little capybara.
As night draws in, capybara leave the water
to sleep in the grassy islands dotted around the wetlands.
But the night brings terrors.
There are monsters lurking.
Caiman do most of their hunting when the sun goes down.
A baby capybara has fallen victim to Iberá's very own villain.
But then a caiman has to eat, too.
Caiman aren't immune to the hidden dangers of the wetlands.
Even an armored giant has enemies.
Like most reptiles, caiman are cold-blooded.
They rely on the hot Argentine sun to raise their body temperature.
This early in the morning, they're out in force,
soaking up the sun.
But their daily warm-up leaves them exposed.
The caiman has reason to fear.
The jaguar is the top predator of neotropical forests,
but now they are more often found
n the continent's legends than the landscape.
Humans have hunted jaguar to prevent them stealing their livestock.
Now, they are only occasionally seen in Argentina.
But they still roam the Atlantic Forest and waterways
not far from Iberá.
Relative to weight, jaguars have one of the strongest bites
of all big cats in the world.
This male could easily chew through a turtle's shell...
so a caiman would pose no problem.
He's the king, and he's hungry.
Hiding in the long grass won't help the caiman now.
The jaguar's incredible jaws easily puncture the caiman's armor.
It's a rare payback for the greediest hunters of the wetlands.
No one seems to notice the drama.
Routines resume.
As soon as they are warm enough,
the caiman slink back to the shallows.
A safer distance from the lethal jaws of the jaguar.
In Iberá, Argentina's wetlands,
with water levels at their highest of the year,
fishing becomes an art form for yacare caiman.
But they've been doing it since the dinosaurs.
They float just below the surface of the water,
with their legs spaced wide apart.
Staying perfectly still they pick up the vibrations of passing fish.
They bide their time.
They'll only expend precious energy for a big enough fish.
And when it comes...
their reactions are lightning-fast.
Any fish could become an unlucky victim...
but a yacare caiman's favorite meal is the piranha.
In the brilliant waters of the wetlands,
piranha steal the show with their glittering scales.
These fish are ancient inhabitants of Iberá.
Their ancestors were freshwater residents of the continent
over 25-million years ago.
These are social fish, and travel together in shoals.
Despite their ferocious reputation and scary teeth,
piranhas aren't known to attack large mammals unprovoked.
But if another fish strays too close,
t only takes one piranha to make the first move.
Nipping the fin of a passer-by...
before the others follow and a frenzy begins.
The piranha strip the meat from the bones.
Their tooth enamel structure is similar to a shark's.
Interlocking teeth make light work of shredding their meal.
It's over in minutes.
These voracious fish can be found all over South America.
Linked by the great river systems
that still weave their way across the continent.
The Iberá wetlands cover
what was once the meandering channels of the Paraná River.
After the Amazon, this is the largest river in South America.
It once flowed freely across these lands,
but tectonic activity forced it to carve its course westwards.
Its ancient tracks are still evident today.
Lakes have formed in the place of ancient eddies,
and shallow rivers follow the deepest grooves
nflicted by the fierce currents of the old river.
Now the wetlands behave like a dam...
trapping rain in the depressions of the ancient riverbed...
and filtering water down into one of the largest underground reservoirs
n the world.
Cut off from much of Argentina...
these wetlands are pristine.
Wildlife has flourished.
Small pockets of subtropical forest are dotted all over the wetlands.
They are a reminder of Iberá's past.
These forests once stood on islands in the Paraná River basin.
Today they remain disconnected.
And are still occupied by an old resident.
In the early morning a strange call sounds out from one of the islands.
This ghostly noise is from Iberá's only primates.
Howler monkeys.
Every morning they howl to let other troops in the area
know their position.
These pockets of forest are prime real estate for howler monkeys.
It's important they keep their distance.
The males have specialized vocal chambers
to help them project their calls.
Their voices carry up to five kilometers away.
Males are jet black,
but the females and young are gold.
This is thought to help the males know who to fight with,
and the females who to mate with.
After their morning ritual
they lazily forage for food, and nap during the hottest hours.
It might seem like an easy life now,
but dangers await the youngest members of the group.
When they reach adolescence, they will have to cross the wetlands
under the cover of darkness to join a new group.
It's a daunting initiation into adulthood.
The stretches between patches of forest
can be several kilometers wide...
and there's no guarantee of being accepted once they arrive.
The howler monkeys aren't the only residents
of this northern corner of Argentina,
who have to contend with perilous journeys.
A tiny creature has a way of making its mark on Iberá's landscape.
Their tracks signal their presence all over the wetland.
These tracks have been worn into the ground
by up to eight-million leafcutter ants.
And the nest could be over five meters deep.
These ants are highly organized little creatures.
Like all ant societies, every leafcutter has a role
that they are specially adapted to.
These ants are one of the largest in the colony.
They shear off pieces of leaf
by vibrating their jaws 1,000 times a second.
And drop the goods down to a waiting convoy of smaller ants...
who then transport it back to the nest.
Back in the nest, these tiny pieces of vegetation
are broken down and turned into a fungus garden for the ants to eat.
They're Iberá's very own underground farmers.
But not everyone here has the ability to cultivate food.
Some meals are salvaged from an unsavory source.
A capybara has died making the crossing between lagoons.
Capybara can live to around six years in the wild,
but they rarely get to die of old age.
This male might have been attacked by another,
or simply fallen victim to the midday sun.
The corpse is several days old,
and is rotting quickly in the humid wetland.
In a frenzy the flies feed and lay eggs,
which hatch into maggots.
Other visitors follow.
Caracaras have a poor sense of smell,
but they are extremely clever birds.
They rely on visual cues to find their food,
and the flies have shown them the way.
In the pecking order of the wetlands,
the caracara is fairly low down the list.
An Argentine gray fox has also tracked the capybara down.
But she has company.
Her mate follows her lead.
She lets him know to wait his turn.
She needs more food than him.
She's producing milk for their pups hidden in a den nearby.
Until they're weaned, they're totally dependent on her milk.
Many in the wetland benefit from the capybara's misfortune.
And nearly everyone here is a scavenger.
In the middle of December, summer in the wetlands
drives the midday temperatures to almost 40 degrees.
Some of the wetlands most notorious scavengers
are starting to feel the heat.
American black vultures are carrion feeders.
They know all too well the hunting skills of caiman.
And they have an understandable fear of the water.
But birds don't have sweat glands,
so the searing heat forces them into the shallows.
This bank is a popular spot,
and with everyone wanting a dip, squabbles are common.
The water provides some relief, but they don't hang around.
They dry off on the bank, holding their wings out in the heat.
This is thought to help sear off bacteria.
Even reptiles spend the hottest part of the day in the shade.
The black and white Argentine tegu
s a giant amongst lizards,
with the males growing over a meter long.
These beasts spend most of their time
patrolling their territory in search of food.
Tegus use their long, forked tongues to smell the air around them.
The tongue collects scent particles in the air,
and transfers them to a special organ on the roof of their mouth.
They're not fussy.
Anything small enough to fit in their mouths is eaten.
And anything besides is worth a try.
He's found an abandoned rhea egg.
Some rhea eggs are used as decoys for predators,
and are then left behind.
It's a fantastic find, and it'll be a delicious feast...
f he can ever crack it open.
His attempts are nothing short of embarrassing.
On the bank of a marshy lagoon in northern Argentina,
an unusual nest sees the first sign of movement for months.
The nest is well disguised.
A heap of rotting leaf litter, twigs and mud
rests just above the high water level of the wetlands.
Strategically placed for a getaway.
With determined force
the first of the miniature mysteries breaks through.
Baby caiman are surprisingly cute.
Though they'll grow up to be fierce and unforgiving hunters,
at this age they are defenseless.
Unusually for a reptile, their mother is very protective.
She waits in the wings for the rest of her offspring
to make a break for it.
Within minutes there's a mass exodus of baby caiman.
Their survival instinct begins at birth.
They head straight for the water.
But even the water isn't safe at this size.
The hatchlings spend the first year of their life hiding,
staying close to their mother's territory to avoid predators.
But some don't even make it this far.
A curious caracara has picked up an unopened egg from the nest.
This little guy didn't stand a chance.
Those that do survive stay together in little rafts for several years.
There's safety in numbers.
But it won't be long before the tables will turn.
Many of the creatures that hunt young caiman
will in the future become their prey.
Northern Argentina's wetlands are an emerald jewel
n South America's crown.
A pristine Eden...
rich in color and creatures.
In Iberá the jaguar is a seldom-seen king.
And every animal and plant has its place in his domain.
In these lush and fertile lands,
wildlife thrives,
even in death.
Whether beneath the surface or above...
Argentina's Iberá's water kingdoms are a paradise on Earth.
Subtitles: Asha Chong www.btistudios.com