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.

These are tales of life from the African plains...

and America's Sonoran Desert...

..in the Hidden Kingdoms.

MOUSE HOWLS

East Africa...

and the largest animals that walk the Earth.

But look closely beneath their feet

and you will see a network of tiny trails...

..and the tiny creature that constructed them.

She's an elephant shrew,

known by her African name "sengi".

Trails like this are the secret to a sengi's survival.

They're race tracks that allow them

to sprint through this miniature jungle.

To escape their enemies and chase down food,

all they really need...

is speed.

For their size, a sengi is twice as fast as a cheetah.

Just off trail is her youngster.

Sengi babies spend their first few days in hiding,

waiting for their mother's fleeting visits.

The mother's high-speed lifestyle

requires even more fuel now that there are two mouths to feed.

She's forced to forage in the far corners of her territory.

Generations of termites built this mountain fortress...

but now it's the home of a hunter.

ROARING

A monitor lizard can taste a scent trail.

But the forked tongue does more.

Its shape means it tastes in stereo...

..so it not only knows that prey passed by,

but in which direction it was headed.

SHE SQUEAKS

A mother's instinct is to lure away the danger.

Sengi know their trails so well,

they can normally outrun an enemy.

But the world above is beyond their control.

With the trail suddenly blocked,

there's no escaping the predator.

SHE SQUEAKS

With her mother gone,

how will the youngster learn the secrets of sengi life?

Nearly 10,000 miles away,

on the other side of the world,

a different hidden kingdom...

..in America's Sonoran Desert.

Long before the first human settlers,

there were already families

struggling to make this wilderness home...

..and they're still here.

A family of grasshopper mice.

The father has long gone.

This mother is raising four hungry mouths alone.

20 days after they arrived

kicking and squeaking into the world,

they're furred and feisty.

They're not quite ready to make it on their own,

except for one.

An hour older and bolder than his brothers,

he already has the urge to explore the world beyond his birthplace.

DISTANT HOWLING

Every night, his mother goes out to find food.

And she sees things out there that could scare a young mouse to death.

There are more venomous creatures here than anywhere in the USA.

THUNDERCLAP

No place for the timid.

But she's not your average mouse.

Her kind has never known a time without this ancient adversary.

It's why old-timers would call her by an earlier name...

..scorpion mouse.

The sting of a scorpion can cause death in humans.

But a grasshopper mouse has almost superpowers.

Their reactions are faster than a scorpion strike...

..their bodies immune to the venom.

They specialise in killing deadly prey.

MOUSE HOWLS

To defend their territory, they stake a claim

with a warning howl.

HIGH`PITCHED HOWLING

If we were shrunk to mouse size, it would sound more like a wolf.

The young grasshopper mouse knows nothing

of the dangers outside his door.

But barely three weeks old,

growing curiosity means he's about to face them.

The desert will soon have him running for his life.

In Africa, the orphaned sengi must learn to fend for herself.

Without a mother to guide her,

she has no sense of who is friend or foe.

Curiosity gives way to hunger.

For the first time, she's driven onto the trails her mother left.

A young sengi must eat every few hours.

Catching enough food is a challenge.

It's no good trying to fight through thick grass.

Obstacles just slow you down.

The penny drops.

The trail is the key to finding food fast.

So, to maximise speed, a spot of spring-cleaning is in order.

The smaller the mammal, the higher its metabolism.

So, in the hidden kingdom,

there's a constant race to fuel your lifestyle.

It's why sengis are a little...fussy.

They can spend half their waking hours tidying their home.

The sengi needs to clear away everything that gets between it...

and its food.

But no matter how hard you work,

some problems are just too big to deal with...

..even for the most house-proud sengi.

RUMBLING

SHREW SQUEAKS

ELEPHANT RUMBLES

ELEPHANT TRUMPETS

Things seemed to be going so well.

Luckily, in the hidden kingdom, help is at hand.

Dung beetles can sniff the whiff of dung half a mile away.

Within minutes, thousands helicopter in.

Without these miniature marvels,

the savanna would be drowning in dung.

Serrations on their head saw it up...

..and legs like spades shape the dung into perfect balls.

Most just take enough to eat.

Others are out to attract female company.

And for that, the bigger the balls, the better.

She climbs on board for the ride.

Later, she'll lay her eggs inside...

..as soon as the male finds them

a secluded spot where they can start a family.

Pound for pound, a dung beetle is stronger than an elephant.

Sadly, this is no consolation when their worlds collide.

Still, it's not all bad.

At least the trail is clear.

Alas, bigger problems are brewing on the horizon.

THUNDERCLAP

In the Sonoran Desert, the remaining youngsters

wait patiently in the burrow for their mother.

HIGH-PITCHED HOWLING

They're getting a taste of the world outside.

So far, their mother has protected them from its dangers.

But there's nothing she can do for her eldest.

He faces his first night in the desert alone.

The heat absorbed by this desert road lures insects at night.

It's the perfect place for a hungry mouse to find food,

and for others to set up an ambush.

There are more rattlesnakes here than anywhere else on Earth.

A grasshopper mouse tiptoes through a living minefield.

Grasshopper mice face deadly locals every night.

Usually a dry riverbed would be a place of safety.

But tonight a powerful force threatens...

..one so rare, a mouse could go its whole life without seeing it.

This refuge will soon become a trap.

There are places in this desert

that don't see a drop of rain for 1,000 days.

Yet when it does arrive, a year's worth can fall in a single night.

For one so small, wet fur can lead to a fatal chill.

A mouse shakes up to 30 times a second, generating forces of 70G.

It may have rained,

but months of blazing sun has baked Arizona's earth as hard as stone.

The water can't soak away.

Instead, it gathers momentum

as it races downhill.

To us, it's a tiny stream.

To a mouse, it's a 12-inch high tsunami.

MOUSE SQUEAKS

Back in Africa, the grassland is tinder-dry.

For now, life in the Hidden Kingdom appears tranquil.

When it comes to perseverance, a young sengi could learn a lot

from Africa's hard-working waste disposal expert.

Dung beetles can push the equivalent of a three-tonne truck.

It provides all the food this male's family will ever need.

The trouble with keeping your head down, though,

is that you can't always see where you're going.

Dung beetles don't give up.

Even when they've lost the ball, they get right back on,

heading off in the same direction, no matter what is in their way.

The secret to super strength is diminutive size.

Small animals weigh less,

so waste less muscle power moving their bodies.

Relative to body weight, the smaller the animal, the stronger it becomes.

They are unstoppable.

Almost.

Wildebeest stampede for a reason.

Down here, you're the last to see trouble ahead.

A sengi's trails are its greatest strength

and its Achilles heel.

They're so dependent on them, they're effectively a prisoner.

Every year, lightning sets the bone-dry savanna alight.

Few small creatures can escape the inferno.

When fire threatens, she can outrun the flames...

..but it's into the unknown,

leaving the very trails that kept her alive.