BBC Hidden Kingdoms

Our planet is home to millions of different animals.

The big and the powerful capture our attention.

But there is another story to tell.

Beneath our feet are hidden, almost magical worlds...

..teeming with extraordinary little creatures.

The world looks very different to them.

A falling acorn...

..becomes a meteor.

A tiny trickle,

a tsunami.

And every enemy...

is a giant.

Now, using the latest technology,

we can recreate the world from their perspective.

In this episode,

we enter the secret worlds of two urban jungles -

the chaos and commotion of Rio...

..and the futuristic metropolis that is Tokyo.

These are dramatic tales of life inside the Hidden Kingdoms.

Tiny marmoset monkeys,

small enough to sit in the palm of your hand.

They're a close-knit family,

at home in the tree tops of the forest.

But this is no ordinary forest.

Rio de Janeiro.

This vast city

crammed with over six million people

is eating into the jungle.

But some jungle creatures

are standing their ground.

The only way to survive

is by making the most of what humans can offer.

For a gang of marmosets,

finding food in the city

means leaving the safety of the trees.

It's a journey fraught with danger.

One young male is bold enough to lead the way.

To marmosets,

these power cables are like tree branches...

..if a little more slippery.

Surveying the streets below, they can spot any opportunity for a meal.

The streets of Rio

are strewn with discarded litter.

But they are also patrolled by cats and dogs.

To survive, the marmosets must work as a team.

Look-outs sound the alarm.

Young marmosets are more inquisitive than the adults.

The city is so noisy,

it's hard to hear the others calling time to move on.

The link to the rest of the family has been severed.

He has no choice but to take to the streets.

How can this young marmoset survive

without the protection of his family?

On the other side of the planet...

..Tokyo.

With well over 30 million people,

there's barely room for any green space.

This concrete jungle

is one of the most inhospitable places on earth

for wild animals.

But there is one out tonight,

an armour-plated mini monster...

..a rhinoceros beetle.

Removed from the forest, he's now a captive...

..and a gladiator.

Introduced to another male,

all he needs to do

is what comes naturally to him...

..fight.

The winner is the one who throws the other on his back.

He wins.

Beetles usually eat high-energy tree sap.

Here, some fruit will have to do.

Then he's back in the ring.

For their size,

rhinoceros beetles are the strongest creature on Earth -

able to lift over 100 times their own body weight.

Males with longer horns are more likely to win

and this male's horn is as big as they get.

But even he's not invincible.

Nonstop fighting is exhausting.

No longer a hero,

he's just an unwanted bug.

Now the only hope for survival

is to find an oasis amongst the concrete.

Back in Rio,

the young marmoset is searching for his lost family.

Down at street level,

he is far from alone.

A cane toad -

quite at home in the gutter...

..and poisonous to the touch.

The warning rattle of a snake...

..mimicked by a burrowing owl to keep intruders away.

Burrowing owls have adapted well to city life...

..and even enjoy a trip to the beach.

Rotten food isn't on the menu,

but collecting it is all part of a plan.

Just one more trip is needed.

This time, to visit the local agouti.

Agouti usually live in the forest,

but these have come to feast on scraps left by the residents.

It looks like the owl has hit the jackpot, too.

A crowd this size would never occur in the forest

but here, food is abundant.

The agouti barely notice one more mouth to feed.

Cats, on the other hand, miss nothing.

The city owl is too quick for a cat.

Back at the burrow,

it's time to put the plan into action.

It's not long

before visitors are attracted to the smell.

He's been setting a trap all along.

Burrowing owls live on a diet of bugs.

In the wild, owls use animal dung as bait,

but this one has adapted brilliantly to city life

and can now enjoy its own home delivery service.

Life is not proving quite so easy for the marmoset.

Without the rest of the gang to help him,

the youngster is very hungry...

..and very alone.

In Tokyo, the rhinoceros beetle is not just alone,

but still miles from any oasis.

He does have one trick up his sleeve, though...

..a huge pair of wings...

..and the strength to perform a vertical take-off.

He may have escaped the back streets,

but flying around Tokyo's skyscrapers

is a precarious business.

He isn't alone.

The sky is filled with other nocturnal bugs.

Insects normally navigate by the light of the moon.

Tokyo's lightscape plays havoc with their map reading.

Light radiates in all directions...

..and the confused bugs are lured closer and closer...

..right into the path of a predator.

The glaring lights don't distract bats.

They see with sound.

Listening to the echoes from its high-pitched calls

allows the bat to form a detailed picture

of the world around it.

A large, clumsy rhinoceros beetle

might seem a tempting target.

One way to avoid capture is to drop out of the sky.

That's one thing a heavy beetle can do well.

Bats aren't the only animals up here feasting on the glut of bugs.

It's warmer in the busy city than in the surrounding countryside,

so very attractive to cold-blooded geckos.

The extra heat speeds up the lizard's metabolism,

allowing it to strike with lightning speed.

In the forests,

geckos hunt on the trunks of tall trees,

so a Tokyo skyscraper is home from home.

Gecko feet can normally stick to anything.

Unfortunately, the tall buildings and the warm city air

can create a problem never found in the forest.

The swirling currents of air

form millions of mini tornadoes.

There's too much turbulence, even for a gecko.

When its grip fails, a gecko can glide to safety.

But he's landed on someone else's patch.

The hungry rhinoceros beetle has gate-crashed too...

..all in the sight of the deadliest man-eater in Tokyo.

In Rio's labyrinthine streets,

there are endless places for animals to hide.

A leafcutter ant has left the security of its family

to scout for food.

Ants use their antennae to detect food.

This is fuel for the colony.

Within minutes, fellow workers are by her side,

having followed a trail of chemicals

that she has deliberately left behind her.

The ants must work fast.

Down here, exhaust fumes can create a thick toxic smog.

Now they must take the long road home,

back to the rest of the colony.

As the first worker ants

reach the safety of the underground colony,

city life is about to come crashing in on their world.

Washed away from the colony,

any chance of finding the way back seems impossible.

But there's help to guide them.

Despite the flood, the chemical trail is still strong.

A single gram of it would be powerful enough

to create a trail around the entire globe.

Such extraordinary communication and teamwork enables leafcutter ants

to overcome whatever the city throws at them.

The only way marmosets can keep in touch is by calling.

For a moment, the young male thinks his calls are being returned.

But the noises of the city can be deceptive.

It's not the call of his family, but the sound of a truck braking.

Down on the streets, there are trucks everywhere.

Back in Tokyo, the beetle has landed in the lair of a man-eater.

This praying mantis is trying to attract a mate.

The breeze will carry her scent to the city beyond.

Out on the town, a male is quickly hooked.

But he's aware of this lady's reputation.

He has to exercise a bit of caution.

This city breeze will work in his favour,

distracting her from his approach.