The islands between Australia and Asia
are among the biologically richest on Earth.
♪
They are home to the beautiful...
and the bizarre.
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This is a world where birds hatch from active volcanoes,
pigs box,
and kangaroos climb trees.
A wealth of life shaped by nature's most violent force,
the power of the Earth.
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Over eons, volcanoes have forged a land like no other.
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A place where, to survive, life must adapt.
[rumbling]
Volcano birds lead one of the most extreme lives
in the natural world.
[rumbling]
Each day, dozens of birds gather in an act of apparent madness.
[rumbling]
In a deadly realm of bellowing ash and toxic gas...
The volcano birds are uniquely adapted
to turn devastation into an opportunity.
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Temperatures around the volcano are sweltering.
But it's this warmth they're after.
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Volcano birds have enormous feet, perfect for digging.
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They search for spots around the volcano
where the temperature is just right...
a balmy 91 degrees Fahrenheit.
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These coveted spots are worth fighting for.
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And this is why.
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Her only act of parenthood is this offering to the volcano.
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The heat of the slopes will incubate the egg for her.
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The egg takes a long time to hatch,
among the longest of any bird.
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But when it does, the chick is flying within an hour.
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With an active volcano as the only parent it will ever know,
the chick is on its own from day one.
[rumbling]
Here, the Earth's violent power has driven the evolution
of an astonishing array of species.
This is the front line in a story that has been unfolding
for millions of years.
And one that continues to this day.
Around 25 million years ago,
Australia, surging north into the tropics,
began to collide with Southeast Asia.
At the tip of the continent,
New Guinea was thrust up amidst the carnage.
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The island's ancient connections to Australia
are evident in the animals in its forests...
some of which have undergone a dramatic lifestyle change.
[squawking]
Kangaroos aren't exactly known for climbing trees.
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But with lots of leaves and few others to eat them,
it was an opportunity they couldn't miss.
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Australia's shift north was so quick,
tree kangaroos haven't had long to adjust to life in the canopy.
♪
Their arms have become stronger,
but it's obvious they were originally built
for hopping over open plains.
Kangaroos may hold sway in the treetops,
but for the most part,
New Guinea is an island of birds.
The largest is the cassowary.
It's from an ancient lineage that's roamed the Earth
since the time of the dinosaurs.
[squawking]
But most extraordinary of all are the birds of paradise.
[squawking]
The very story of New Guinea
is written in their profusion of plumes.
[chirping]
[whistling]
Birds of paradise all descend from one Australian ancestor.
But the mountain ranges created by the continental collision
separated populations from one another.
So the birds have evolved into several dozen different species.
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There's such an abundance of food in the tropical forest,
the males aren't needed to help raise chicks.
They put all their effort into one thing: winning a female.
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This male bird of paradise has one focus:
a perfect performance.
The female's focus is to choose the best possible mate.
Her inspection is thorough.
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Females are so critical,
that every step of his routine has been selected and perfected
over countless generations.
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It's this ability to choose
that drives the evolution of new species.
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And it's led to very different displays.
From bizarre shape-shifting...
...to spectacular plumage shown off at group gatherings.
[squawking]
All this beauty is the result of New Guinea's violent beginning.
But this is a young island, as the tree kangaroos show.
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Giant feet once perfect for hopping
take a long time to adapt for climbing.
They have a long way to go
before mastering the tropical treetops.
The islands at the opposite end of the chain
have a very different tale to tell.
♪
These western isles are home
to some of the greatest tree climbers on Earth,
the primates.
♪
[whooping]
The gibbon is the true master of the treetops.
They reach top speeds of 30 miles an hour,
and clear nearly 50 feet in a single swing.
They're the ultimate canopy specialists,
equipped with hooked hands and extra-long arms.
[whooping]
The contrast with New Guinea's kangaroos is crystal clear.
Gibbons have had an enormous head start.
[whooping]
Their home has been in the tropics
for more than 100 million years.
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Gibbons have had plenty of time to master the high life.
[whooping]
These western islands are all part
of the same continental shelf.
During past ice ages, when sea levels were lower,
species from mainland Asia
crossed freely to Borneo, Sumatra and Java.
These forests are filled with mammals,
most of which simply walked here.
♪
The Sumatran rhinoceros is a rare sight.
Fewer than 100 are thought to remain in the wild.
Bizarrely, she's the world's hairiest rhino.
It's a feature retained from her mainland relatives,
the now-extinct woolly rhinoceros
that roamed Asia during the last ice age.
A hairy rhino in a hot, humid rain forest
may seem out of place.
But her hair has a purpose.
♪
Sumatran rhinos love a good mud bath.
This hole left behind by a fallen tree is the ideal spot.
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She bathes every day, dipping herself for hours at a time.
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But these mud treatments don't come easily.
She has to work to keep her tub open,
so it collects as much rainfall as possible.
Here in her mud bath, the reason for all her hair becomes clear.
It helps the mud stick to her skin,
keeping her cool in the heat.
With their impressive range of Asian animals,
these rain forests are some of the biologically richest
on the planet.
But they, too, were forged by fire.
[rumbling]
Volcanoes have ruled the islands between Asia and Australia
for millions of years.
Their unpredictable nature controls all life here.
♪
When the giants stir, they create deadly realms.
This is Ijen on the island of Java.
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Its crater is a cauldron of acid.
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Alongside it, toxic gas howls from beneath the earth.
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Reaching temperatures around 1,000 degrees Fahrenheit,
some of the gas condenses into streams of liquid sulfur.
There is beauty in this poisonous landscape,
increasing as darkness falls.
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When the gas collides with oxygen, it catches fire,
burning with a soft blue light.
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The liquid sulfur continues to burn, creating rivers of fire.
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Ijen's blue flames dance only in the darkness.
A sight so fleeting, that as day dawns, they vanish.
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While Ijen's crater is a toxic world,
other volcanoes rule with extreme violence.
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At 60 miles long and 1,600 feet deep,
Lake Toba is all that remains
of the most powerful volcanic eruption in human history.
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[rumbling]
Toba erupted 75,000 years ago,
ash clouds soaring into the sky.
[rumbling]
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Despite Toba's violent destruction,
a land of incredible biodiversity lies in its wake.
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Volcanic ash is rich in minerals.
Over time, they break down, making the soil very fertile.
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Today, the forests around Lake Toba
are among the richest ecosystems on Earth.
Over 10,000 different plant species
grow on these fertile volcanic soils.
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There are so many different fruiting trees,
the orangutans who live here are spoiled for choice.
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Individuals develop favorite fruits and unique diets
that they pass on to their offspring.
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As this baby grows, he will learn the locations
and fruiting times of this setur tree.
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So while mom's favorite fruits will form much of his diet,
nearby, another youngster could be raised on different fruits.
Today, it's rambutan.
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These orangutans have the volcanoes to thank
for the sheer variety of fruits on the island.
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On Sumatra, young volcanic soil supports an abundance of life.
But as soil ages, it becomes less fertile.
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Borneo is an ancient island,
much of its rock thrust up tens of millions of years ago.
Without fresh volcanic ash,
some plants have had to take extreme measures
to find nutrients.
They've become carnivores.
These are carnivorous pitcher plants.
Their traps are modified leaves.
As the blade opens, the large vein in the center of the leaf
continues to extend outward.
Over several weeks, the tip inflates.
♪
Finally, the deadly trap is revealed.
A liquid-filled chamber with no escape.
With more than 30 species of pitcher plants,
Borneo is their heartland.
Sizes and positions of traps vary,
but all share a common goal:
lure in prey with nectar.
♪
A slippery rim sends the prey plummeting into the pitcher,
where digestive fluids dissolve the victims' bodies.
Beyond this basic method, some have even more astonishing ways
to get the nutrients they need.
A few pitcher plants engage in remarkable relationships
that stretch beyond carnivory.
The broad, exposed back wall of the pitcher plant hemsleyana
has evolved to reflect the sonar of a small bat.
After a night on the wing,
the pitcher is an ideal resting spot.
It's a perfect fit, just wide enough to stop the bat
from slipping down into the digestive fluids.
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The traps provide a parasite-free
and cool place to sleep.
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It's a great arrangement for the bat,
but how the hemsleyana benefits
isn't clear until evening arrives.
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As it stirs, the bat pays its way in poo,
supplying nutrients the plant can't get from the soil.
This hemsleyana has become a bat toilet.
Just one of the many ways nature has adapted life
on Borneo's ancient soils.
The violent, shifting earth
ensures that change is the only certainty
on the islands between Asia and Australia.
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To survive, life must adapt and seize opportunities.
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And nothing presents an opportunity
quite like an entirely new island.
With new land to colonize,
species just need a way of getting there.
Plants are the obvious early colonizers of any island.
Grasses, their seeds blown on the wind,
are some of the very first to arrive.
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Others take to the sea to make the crossing.
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Coconuts can still germinate
after a couple months of floating in the open ocean.
Liquid inside the coconut helps the young plant get a foothold
beneath the baking tropical sun.
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Animals swim these tropical waters, too.
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With its streamlined body and flattened tail,
monitor lizards can swim between the islands.
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As a scavenger and a carnivore,
they're well equipped to find the food they need to survive.
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By air and by sea,
new islands are soon filled with a rich diversity of life.
And some animals play an important role
in turning a few trees into a rain forest.
[chirping]
Fruit bats can bring new life to distant worlds.
As evening approaches, the roost stirs.
♪
Under cover of darkness, they leave their new island home
and fly miles across the water to the mainland
in search of fruiting trees.
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By dawn, the bats return to the safety of their island roost,
bellies full of fruit.
[chirping]
And now, in their droppings,
they deliver the seeds of those fruits to the island...
literally.
The bats deliver large batches of seeds each day,
with their own dose of fertilizer.
[chirping]
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Turning a handful of trees into a thriving rain forest.
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Cut off from their mainland kin,
inhabitants of these islands evolve into new species.
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Long isolation defines the islands
that lie between Australia and Asia.
Separated by deep water channels,
these islands belong to neither realm.
Some were born of fire.
Others were torn away as the continents collided,
carrying animals with them.
On the island of Halmahera, the forests are home to a stowaway,
cut adrift for some 11 million years.
Before dawn, the males gather.
[chirping]
The standardwing bird of paradise.
[chirping]
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Their aerial display is totally unique,
as are their translucent feathers.
[squawking]
Very little is known about these peculiar creatures.
♪
[squawking]
Their display seems to be a bizarre mix of the gatherings
and dances of New Guinea's birds of paradise.
They're adorned like the plumed dancing birds.
But daylight also reveals an iridescent breast shield,
much like the shape-shifters.
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Standardwings are perhaps the most unusual bird of paradise.
But on the island of Sulawesi, Halmahera's neighbor,
lives even stranger stowaways.
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Sulawesi is made up of land from both Australia and Asia
and is home to a mix of animals
that evolved on the two completely different continents.
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This mineral spring, hidden deep in the rain forest,
sets the stage for a bizarre cast.
There are creatures on the island of Sulawesi
that have been isolated here since the ancient past.
The true stars are the shy and seldom-seen babirusas.
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The babirusa is a type of pig,
cut off from their Asian relatives
for as long as 20 million years.
They've evolved into unique pigs.
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Their piglets lack stripes and are born in ones and twos,
rather than large litters.
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Babirusas emerge from the forest in family groups,
with dozens visiting the spring each day.
So many come to drink that it soon gets overcrowded.
Much to the frustration of the local macaques.
As strange a spectacle as this is,
nothing quite compares to the male babirusa.
Its tusks grow through the roof of its mouth.
According to local lore,
males use them to hang from branches while sleeping.
No one seems to know for sure,
but they're apparently not for fighting.
[squealing]
When male babirusas face off,
the conflict is settled by boxing.
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Another unique creature joined the boxing babirusas on Sulawesi
when the island collided with yet another land mass.
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Like the babirusa,
the bear cuscus has been confined to Sulawesi
for some 20 million years.
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Its prehensile tail acts like an extra hand,
helping it move through the rain forest trees.
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But the bear cuscus is actually a marsupial.
It drifted here all the way from Australia.
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Northern Sulawesi, a land of fire,
tells a different story.
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Thanks to the volcanoes,
the rain forests here are more robust than those further south.
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So these crested macaques have a rich and varied diet.
There's so much fruit
that they can live in troops over 100 strong.
With so many living side by side,
communication is an essential part of keeping the peace.
Each expression conveys a different message,
so others know how they're feeling,
be it threatened, aroused, or submissive.
[chattering]
These are the most sociable macaques in the world.
They can spend hours grooming each other.
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Sulawesi is this region's most extraordinary island.
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It's an ancient land of stowaways
torn from different worlds, ruled by the Earth's raw power.
Over millions of years,
the power of fire has turned these islands
between Asia and Australia
into some of the biologically richest places on our planet,
and created a home for some incredibly unique creatures.