Burning North Mexico: Earth's Festival of Life

In the heart of the Americas,

where continents collide,

there's a land full of natural riches.

A land of towering giants...

..scorching sands...

..and secret rivers.

Where great civilisations rose...

..and fell.

To succeed here takes passion and spirit.

This is a country rich in colour and culture.

A festival of life.

This is Mexico.

Just south of the American border is a little-known world...

..Northern Mexico's prairie lands.

These dry grasslands are home

to one of Mexico's most sociable animals...

..the black-tailed prairie dog.

They live in extensive colonies comprised of dozens of families,

each with a dominant male, several females

and their offspring.

In May, their six-week-old pups take their first steps above ground.

Grasses and other prairie plants provide all the food

and moisture these vegetarians need.

But feeding in this open terrain

comes with risks.

Their burrows offer an escape from birds of prey

and coyotes.

But they're no protection

from one of the prairie's most persistent hunters...

..the bullsnake.

This powerful constrictor could easily

suffocate an adult prairie dog.

PRAIRIE DOG SQUEAKS

But it's pups he's after.

And they are hiding somewhere in their burrow.

PRAIRIE DOG SQUEALS

Their father would be foolhardy to follow this predator underground.

The snake's found nothing down this hole,

so he's on to the next.

To save his pups, their father must somehow drive the snake away.

PRAIRE DOG CALLS

He stands to warn others where the snake is.

Repeated strikes may just drive it away.

PRAIRIE DOG CALLS

The snake concedes defeat.

On the open prairies, there's safety in numbers

in this prairie-dog town.

Thanks to their father's bravery,

the pups are safe again.

Northern Mexico sits at a latitude

where high atmospheric pressure dominates.

A little rain ever falls.

This is Mexico's driest region.

Much of it is desert.

It's the least populated, wildest corner of the country.

Journey west and conditions only get hotter,

drier and more challenging.

But for those who overcome these conditions,

there are rich rewards...

..especially on Mexico's northern prairies.

THUNDER

Lying in the foothills of mountains,

at an altitude of over 5,000 feet,

these grasslands catch a little more rain than most of the north.

Between June and September,

monsoon storms roll in off the Caribbean,

helping grass to grow.

For the rest of the year, little, if any, rain falls.

But even during drought, there is water here.

Deep underground,

great reservoirs are trapped in the porous limestone bedrock.

These giant aquifers help support

one of Mexico's most iconic ways of life.

INDISTINCT SHOUTS

HORSE WHINNIES

This is cowboy country.

With year-round water and plenty of pasture,

these prairies are ideal for cattle ranching.

For centuries, people like Servando Diaz Gomez

have worked this land.

Cowboys are rooted in American culture,

but their true birthplace is here in the prairies of Northern Mexico.

In the 16th century, the Spanish

brought cattle and horses to the north,

and trained locals to manage their herds.

The vaquero, or cowboy, was born.

But the dry conditions make ranching tough.

These grasses are easily overgrazed.

Over the last 100 years,

farming and drought have damaged over half of the prairies.

But Servando is one of a pioneering band

trying to reverse this trend.

Using electric fences,

he confines his herd to small blocks of pasture.

Every few hours, they're moved on to the next block.

The grazed area is then left to recover.

It's a practice that's having a big impact.

This healthy pasture is helping Servando rear twice as many cattle.

And wildlife is thriving.

Well-managed prairies offer a rich diet of insects and seeds

for up to three times as many grassland birds.

And they provide food for one of Mexico's rarest creatures...

..the aplomado falcon.

They range as far south as Argentina,

but Mexico's prairies are their northern limit,

where only a handful survive.

Like its relative, the peregrine,

it specialises in aerial assault.

The falcon is much faster in level flight.

But its prey is far quicker on the turn.

Only one in five pursuits ends in success.

But aplomado falcons have a secret weapon...

..breeding pairs hunt together.

Their prey's only chance to escape is to hide.

The falcons need to flush the bird out...

..and two birds are better than one.

Working together, these birds are twice as successful.

And every catch is vital when you're raising a family.

Conservationists have put up platforms

to protect the precious chicks from ravens and owls.

Precious because they are so rare.

There are only five pairs here,

and these are the only ones to successfully breed this year.

But with conservationists and ranchers

looking out for these spectacular birds,

they've hopefully got a brighter future.

Teamwork is important for many in Mexico's prairies.

So, too, is bravery.

Charros are traditionally dressed cowboys

who compete in Mexico's official national sport...

..the charreria.

What was once a friendly competition between neighbours

hundreds of years ago

is now the ultimate display of cowboy bravado.

Each team of charros is made up of specialists

who perform nine different equestrian events across the day...

..that showcase all the cattle handling,

riding and roping skills used in cowboy life.

The most dangerous is saved until last.

Martin specialises in el paso de la muerte...

..the pass of death.

Galloping at full speed,

he has to jump onto the back of a wild, untamed horse

and hang on without reins.

If he falls, he'll be trampled.

Martin now risks everything to secure victory for his team.

In the burning north, success favours the brave.

Mexico's prairies run along the edge of great mountain ranges -

the Western and Eastern Sierra Madres.

Over 10,000 feet high,

they intercept moist air coming from the Pacific Ocean

and Gulf of Mexico.

Beyond the prairies, the land is starved of rain...

..creating one of the biggest deserts in North America.

The Chihuahuan Desert.

It covers an area larger than Britain...

..and receives about half as much rain as the prairies.

But in the heart of this desert

is one of Mexico's greatest natural wonders...

..the valley of Cuatro Cienegas.

It may look barren...

..but this valley hides an oasis.

Here, aquifers break the surface,

creating a water world.

Most of these pools, known locally as pozas,

are fed by thermal springs,

where underground water is forced to the surface by geothermal heat.

Millions of years ago,

when this region was much wetter,

ancient waterways brought fish into this valley.

As the climate dried, the waters receded,

and fish became isolated in pools,

evolving into many new species.

16 species live here,

half of them found nowhere else on Earth.

Including this one,

a Cuatro Cienegas cichlid.

This female has a family...

..and she is the most devoted mother.

Stirring up the sediment,

she exposes tiny plankton for her fry to feed on.

But the biggest challenge isn't feeding her babies,

it's protecting them.

Some cichlids have evolved into predators...

..and in this small pool there are few places to hide.

From dawn until dusk, she must defend her brood.

She has no time to feed herself,

and is getting weaker by the day.

But it's worth it.

Without her help, her young would never survive.

When they're a centimetre long,

they will fend for themselves.

Until then, this mother must give her all.

An astonishing diversity of life

has evolved in this valley.

It's home to more unique species

than anywhere else on the North American continent.

That's the exception to the norm.

Most of this great desert is dominated

by just a few hardy souls.

And one plant copes better than most...

..the creosote bush -

so-called because it smells like wood preservative.

Locals call it la gobernadora -

the governess.

And it governs for a very long time.

One plant is known to have survived

for over 11,000 years.

It's brilliant at coping with drought.

Tiny, resin-coated leaves

drastically reduce water loss.

And its shallow roots quickly soak up any moisture...

..stopping anything growing in between.

Creosote has truly conquered this desert.

Its success has been exploited by a creature

that's addicted to creosote...

CHIRPING SOUNDS

..the creosote bush grasshopper.

It's one of the few animals that can stomach this plant.

It's resinous leaves are indigestible to most animals,

but this grasshopper eats nothing else.

It's even evolved to look like this plant

to avoid becoming food itself.

Most of the bushes have their own resident male.

GRASSHOPPERS CHIRP

Their calls let other males know this bush is occupied.

They're also very attractive to the opposite sex.

This newly-arrived female is exactly what he's been waiting for.

But they are not alone for long.

Another male flies in.

A female is worth fighting for.

He must throw his rival out of his bush.

Easier said than done with so many legs.

Victory for the resident male.

But he's just one of millions of battling grasshoppers

in this endless expanse of creosote.

GRASSHOPPERS CHIRP

Hundreds of miles to the west,

the vast Chihuahuan Desert meets great mountains.

These high sierras catch more rain than the desert below,

enabling forests to grow.

Offering a refuge for a special plant

with the hottest reputation.

THEY SPEAK SPANISH

Every autumn, Armida Elena Contreras Duron

and her husband Eliazar head out to their mountain ranch

to pick wild chillies called chiltepin.

These plants might have a fiery nature,

but they can be remarkably delicate.

They don't like constant exposure to the desert sun.

But this woodland provides enough shade for them to thrive.

6,000 years ago, this wild plant started a food revolution

when it was first domesticated here in Mexico.

It's given rise to thousands of varieties of chillies worldwide.

And with fruit 20 times hotter than jalapenos,

it gives a spectacular kick to Armida's cuisine.

And an awful lot of chillies.

Every type of chilli has a unique flavour.

Chiltepins are particularly cherished

because they are arrebatado,

meaning rapid, or violent.

They're hot, but their heat subsides quickly, and that's addictive.

To Armida and her family, it's part of their national identity.

These mountain forests are one of the few places

where wild chiltepin thrive.

And because of our love of this spicy plant,

its descendants have spread all around the world.

In the foothills to the west,

the sun has shaped another desert

that couldn't look more different.

Stretching over 100,000 square miles,

the Sonoran Desert covers much of Northwest Mexico.

And it's home to the most iconic desert plant of all...

..the saguaro cactus.

The Sonoran Desert is hotter and drier than the Chihuahuan.

And one way to cope is to become gigantic.

Towering up to 18 metres,

saguaros can store great reserves of water.

THUNDER

During summer storms, a season's rain can fall in just a few hours.

The saguaro is built to take advantage of this.

Its shallow roots stretch as wide as the cactus is tall,

and its split trunk allows it to expand like an accordion,

enabling the largest cacti

to absorb one tonne of water during one storm.

It's enough water to last for a year,

making saguaros the lifeblood of this desert.

Even in a drought year, saguaros bloom.

They're a magnet for wildlife.

Almost every creature here relies on this plant,

and not just as a source of food and moisture.

Most of the older cacti are pockmarked with nest holes...

..excavated by Gila woodpeckers.

But squatters often move in.

In this world of giants,

it helps to be tiny.

Not much bigger than a sparrow,

ferruginous pygmy owls easily squeeze into woodpecker holes.

And this female has a family to feed.

Deep inside, chicks are safe.

And not just from predators.

Outside is 40 degrees...

..but this plant's enormous stores of water

keep the interior up to eight degrees cooler

than the surroundings.

A vital refuge for a family of tiny owls

in the crippling heat of the day.

At night, the daytime heat is lost to the heavens.

With such clear skies and no light pollution,

Northern Mexico is one of the best places on Earth

to stargaze.

Under the cooler conditions, the desert comes alive.

Many animals switch to a night routine

to avoid the heat of the day.

Including one of Mexico's most infamous residents.

The scorpion.

Mexico is home to the greatest diversity of scorpions on Earth

and the Sonoran Desert is a stronghold.

But even fearsome predators must tread carefully.

Others are listening in.

In the desert, you've got to grab any opportunity for a meal,

no matter how dangerous.

Pallid bats have become scorpion-hunting specialists.

Their large ears are especially sensitive,

capable of hearing the footsteps of their prey.

As long as this scorpion stays still, it's safe.

But this bat has another way of increasing its chances.

It stalks its prey.

The slightest flinch will give the scorpion away.

Its sting is no defence.

Pallid bats are immune to scorpion venom.

By learning how to hunt one of the desert's most common creatures,

these bats have found a unique way to prosper

in this difficult environment.

It's a big meal, too,

and a vital source of moisture in such a dry place.

On the western edge of the Sonoran Desert,

daytime conditions couldn't be more extreme.

This is El Pinacate.

A landscape with a violent past.

Pitted with volcanic craters and extensive lava flows.

Temperatures can reach 56 Celsius.

Years can pass without rain.

In 1970, astronauts on the Apollo 14 mission

came here to test their lunar equipment...

..because the conditions have created a moonscape.

This is Mexico's driest region.

All the more surprising as it borders the sea.

The Sonoran Desert stretches for hundreds of miles along

Mexico's Pacific coast

and the Gulf of California.

These waters have helped shape this parched coastline.

Fed by the cold Californian current,

these seas produce cool and dry onshore winds,

starving the land of moisture.

Clouds struggle to form...

..creating a coastal desert that extends far out to sea.

In the most isolated corner of the Gulf of California

is a true desert island.

Isla San Pedro Martir.

Giant cardon cacti are one of the few things that can withstand

the drought-ravaged conditions.

There's no fresh water...

..and few obvious opportunities for a meal.

But it's home to an especially resilient resident.

The side-blotched lizard.

Endemic to this island, it's ancestors became isolated on this

barren outcrop seven million years ago.

Being marooned would have been a death sentence for most creatures,

but this stowaway has made a remarkable success of being stranded...

..because of a banquet found just offshore.

The cold seas that created this desert island are some of

the richest on earth.

Nutrient-rich waters are forced to the surface around islands like

Isla San Pedro Martir,

fuelling an explosion of marine life.

In May, the island is transformed into one of the world's largest

breeding colonies of this aptly-named bird...

..the blue-footed booby.

It's the lifeline this lizard has been waiting months for.

Raising a family is a messy affair.

Nests are littered with leftovers.

And this lizard has learned to eat fish.

But to secure a meal, it has to be quick,

there's an awful lot of competition.

These birds have had an extraordinary impact on the lizards

isolated on this island.

With so few species to share this unusual bounty,

they have completely overrun this place.

This island has one of the world's highest densities of lizards...

..over 30 times more than the Mexican mainland.

They are the ultimate proof that even the most barren places

can be bountiful.

If you can find a way,

you really can thrive in Mexico's burning north.

Mexico is blessed with an astonishing diversity of life.

A country bursting with colour...

..and the richest natural heritage...

..with a spirit and vibrancy found nowhere else on Earth.

In making this episode,

the crew travelled to some of Mexico's remotest regions,

capturing remarkable animal behaviour in the wild.

But there was one exception - pallid bats.

They cover many miles of desert every night

hunting scorpions in the pitch-black -

impossible to film under natural conditions.

So the crew teamed up with bat scientist Winifred Frick,

who studies how these bats feed in captivity.

With her help, they brought the desert into a special bat lab

to hopefully film this rarely-seen behaviour.

This makeshift lab on the Baja Peninsula may not be remote,

but it's still presents problems for cameraman Luke Barnett.

It's dark, it's 40 degrees, stuff keeps not working

and power supplies keep packing up, so it's going to be a challenge.

While the finishing touches are put to the set,

Winifred is looking after the stars of the show backstage.

I just think they're beautiful.

They've got these big ears, they have this...almost this little

piggy snout, they've just got a lot of character to their face.

For her studies, Winifred catches wild bats

which she releases a few weeks later.

She feeds and weighs them every day to make sure they're healthy.

To understand their predatory behaviour for scorpions

and understand... I mean, scorpions, they eat,

we have to bring them into the flight cage because

you can't record that in the wild

because we don't know where a scorpion is going to be

and when the bat's going to hit it.

To enter the bat's world, the crew switch to night shifts,

filming in complete darkness using infrared cameras.

But will the bats perform?

Well, it's been quite slow, really,

cos the bats aren't used to the environment perhaps.

And the bats are somewhere in the corner.

I think they're all huddling.

They've got a better idea, they've gone to sleep.

Yeah, midnight and we're all a bit tired and a bit hot.

It ends up being an exhausting

and fruitless first evening for them all.

And a quiet few hours soon turns into a quiet few nights.

Without knowing when a bat might strike,

Luke and the team must stay alert.

Easier said than done when working all night in 40-degree heat.

-We're losing you.

-I know.

The bats are resting. The bat biologist is resting.

Must be the worst bit about being a bat biologist, not falling asleep.

-You find it hard?

-Yeah.

Well, it's funny, I'm actually not a night person.

So my joke is I'm the world's worst bat biologist

cos I'm also claustrophobic.

-So not a night person, I don't like to go into caves.

-Brilliant.

It's now just come up to six o'clock in the morning

and we started about five with great expectations.

A few came down and circled around,

but there wasn't a lot going on, so it's very disappointing.

The bats never go hungry as Winifred feeds them every day.

But after five frustrating nights, the team needs to rethink.

A raised set makes filming more manageable,

but Winifred thinks this is the problem.

We may have to accommodate them,

rather than hoping that they're going to accommodate us.

I think make it work with the cameras and everything,

trying to get the set down on to the ground level

-will be the next thing to try.

-Sure.

We've had to lower the set,

so hopefully now the bats will fly around much more over the top.

It's not been a job that we really wanted to do

cos all we want to do is have a cold shower and sleep, so...

Yeah, another night coming up.

With a more bat-friendly filming set, there's renewed hope.

This looks awesome, you guys.

This looks like exactly where they'd be hunting out in the wild

and getting it down on the floor.

I think it's going to be really key. So I feel pumped. This looks good.

As the bats start to stretch their wings,

they're already showing a lot more interest.

And Luke manages to get some great flying shots of these bats

in hunting mode.

It was much better today,

we lowered the set to the floor and it seemed to make a big difference,

the bats are flying right over the set for a change,

rather than around the outside, low to the ground, so...

we're all feeling a bit more excited.

But Luke still hasn't managed to film the key shot

of a bat catching a scorpion.

As wildlife cameramen know only too well,

capturing behaviour takes patience.

With only a couple of days of filming left,

the bats finally settle in.

-Look at that.

-Oh, look at that. He's moved back.

-Oh!

I can't believe... He's just gone again. We just got a shot.

That is such a relief.

That makes...

That makes me happy because it means that at last we've actually got

what is looking like a sequence.

Without that moment of capture, we'd have nothing.

And there's behaviour that Winifred has never seen before.

When it comes in, it cups it straightaway.

Yeah.

Yeah, look, she just makes that awesome tent with her wings

and her tail.

And the only way out is teeth.

We just never get to see this in the wild.

This is amazing.

Oh, that is beautiful.

-Off she goes.

-Yeah.

It's time to take the bats back to their wild desert home.

There... She's off.

It's been a unique glimpse into

the life of one of Mexico's most secretive animals.