Patagonian Mountains The Dark: Nature's Nighttime World

As night creeps across the planet,

and our familiar daytime world is plunged into darkness...

..strange creatures are beginning to stir.

This is when most animals are active.

The drama of their nocturnal lives, hidden from our eyes.

Now a team of scientists and filmmakers is on an expedition

to the remotest parts of South America.

Whoa, whoa, whoa!

What is that?

Armed with specialist technology,

they will attempt to discover the secrets of the night.

-Holy

-BLEEP!

-I'm getting it. I'm getting it.

She's hunting.

It's a journey into the unknown...

I shouldn't really be out here alone.

..a world where we are blind...

Please don't leave me up here.

I don't know what that is.

Technology will reveal it as never before....

Right now's the most dangerous time to be out here.

He will attack you.

The mysteries of life in the dark.

Don't...run.

Over six months, the expedition is travelling

the length of Central and South America,

from the pristine rainforests of the north,

to the darkest heart of the Amazon jungle.

They've been using their new technology

to illuminate a world hidden from human eyes.

Now on the final leg of their journey,

they have come to solve more nocturnal mysteries

in a new and very different environment...

..the southern tip of South America - Patagonia.

Bryson, Bryson, we're going to head off now

and we're going to check out another ridge line.

All right. We're going to take the other road and loop back around.

'We're going to carry on in this direction.'

Heading up the team of wildlife experts

is biologist Dr George McGavin.

We've come to the Torres del Paine National Park

right at the southern tip of the Andes,

and we've come here to look for the largest ranging

land carnivore in all the Americas - the puma.

The puma is the top predator here.

They're a crucial part of the mountain ecosystem,

but their behaviour has been little studied.

We're pretty sure we know what they do during the day.

They sleep. But what a puma does after dark is a black book.

There is a higher concentration of pumas here

than anywhere else on earth.

The team will use their specialist cameras

to build a more complete picture of their lives.

They have never been filmed hunting after dark - ever.

If we can do that, that'd be the holy grail of puma ecology.

Their first challenge is to find a puma.

That means splitting up and searching by day for possible lairs.

Three miles from George,

night-time camera specialist Justine Evans scans from the air.

There's a huge, huge area.

And there's a series of ridges and valleys, lots of lakes...

and there's little rocky outcrops where pumas can hide away.

Justine is guiding a third team member, biologist Bryson Voirin -

the expedition's tracker.

The most difficult thing about this place is actually finding a puma -

it's like looking for a needle in a haystack,

except this needle is moving around.

Bryson has spent years studying nocturnal mammals.

If he can identify where pumas are hunting,

then Justine can return at night to film them.

'Be careful in there.'

You don't want to corner a puma or scare it.

Justine, I'm seeing lots and lots of game trails here,

so it seems like there's a lot of activity with animals.

By working in different areas,

the team hope to maximise their chances of finding a puma.

I'm just looking for anything I can see -

tracks or signs, bits or remains of animals,

anything that will hand us a clue.

You know, hunting animals, you have to be sneaky,

you have to have a strategy to catch whatever you're routing.

And if you're doing it after dark,

you have to have a special suite of tricks up your sleeve.

Here, the puma's meal of choice is guanaco -

an ancient cousin of the llama.

They are constantly alert -

almost impossible to hunt by day,

but at night, they are vulnerable.

Oooh. Wait. Wait, wait, wait.

There's a kill here. Look, just right next to me.

That is a puma kill.

Right under that bush.

Now, it's been hidden.

What they do is, they hunt for their prey

and they jump on its back and then after it's killed,

they can't possibly eat an animal of this size in one go.

So they hide it under all this brush and it's completely hidden.

They then come back over two or three evenings and eat it all.

And that is the remains of a kill.

So there's a guanaco. That's all that remains of it.

There'll be no more eating here. That's just skin and bone there.

It's proof that a puma is hunting here.

To see the animal in action, the team must return after dark.

Three hundred miles south, in the Magellan Strait,

a second part of the expedition is under way.

Wildlife cameraman Gordon Buchanan will use state-of-the-art technology

to shed light on a marine mystery in these rich waters.

It's probably one of the most treacherous bodies of water

in the world, but it is also one of the most unique marine environments

and the reason being, we've got the Atlantic

and the Pacific coming together right at this point

and what that leads to is a biodiversity on an epic scale.

You've got creatures in this water

from the very smallest to some of the planet's biggest.

One of the largest is the humpback whale.

Ooh, a big humpback whale just here.

Spectacular.

And there's more.

Just here, maybe 300 metres away.

Most humpback whales pass quickly through the Magellan Strait.

This group chooses to stay here for three months of every year.

So little is known about what takes place during the day

under the surface of the water and absolutely nothing is known,

really, about what takes place at night-time.

Gordon hopes to solve a puzzle

that has mystified the scientists that study these whales.

They can hear them coming close to shore at night,

but can't see what they're doing.

Gosh, look at that!

Gordon's specialist equipment could give them the answer.

We have an arsenal of cameras for filming at night-time.

We've got thermal imaging cameras, we've got infrared,

we've got low light cameras.

Pretty much nothing can take place at night-time

without us being able to film it in some way.

Using this technology to film whales at night will be a first,

and could open up a whole new world.

It'd be good to get into the water and find out

what those humpbacks are doing at night,

if they are doing anything. And that's why we're here,

to get out there and just try and answer some questions.

Whoa, whoa, whoa, whoa!

Unbelievable.

As daylight fades, 300 miles north,

the puma team has split to search the area where George found a kill.

This is the time the pumas are just waking up,

going around looking for dinner.

It's a really good time to see them

walking along the hillsides or in the valleys.

Tonight we've got all three teams out

in separate vehicles and driving all the tracks,

and we're throwing everything at it tonight,

getting everyone out there.

It's a large area - we need to spread out as far as we can

and to use a variety of strategies if we're to see anything good.

This puma will have a territory of about 25 square miles.

-Are you ready?

-Yeah. We're ready.

-OK.

They are each searching in a different part of its range.

This is great, because we've got thermal sensing going on,

and visible light. Diego's out the roof with a spotlight,

and I've got the little thermal spotting camera here,

which will reveal the heat of anything warm-blooded

that's out there.

Right now, we're using lights to find the pumas,

but as soon as we see we one, we've got to turn the car off,

turn off all the lights and switch to either infrared

or thermal cameras that don't emit any light,

cos lights will scare the pumas away.

Three miles west, George is with two biologists

who have studied the pumas here for years.

What we're hunting for is green eye shine.

Pumas have got very big eyes,

and they glow bright green in a headlight beam.

So it'll be very obvious if there's one there.

Quick! Quick, quick!

So something just ran out of the bushes. Where'd it go?

Oh, I see the eye shine.

It's moving too fast.

Fox.

Yeah, it's a fox.

While Bryson and Justine continue their search,

George leaves the safety of his vehicle

to check out a ridge above the road with a military spotting scope.

There was definitely, definitely eye shine over there.

It was just by that rock.

Right there!

(There's one just there.)

Yeah, it's just on the hillside. Just halfway up the slope.

Well, it isn't a very clear sighting.

I just saw eye shine.

It didn't look very green. It looked greenish.

But it definitely wasn't a guanaco eye shine.

And it was just over there.

If it is a puma, then I'm right on the top of this ridge.

I mean, it's obvious he'll go.

The animal heads down towards the road.

George radios biologist Rodrigo, waiting in the vehicle below.

I just thought I saw a moving spot

'on a slight slope just southwest of here.'

OK, perfect.

Now Rodrigo must try to intercept the animal as it crosses the road.

Stop, stop, stop.

Did you see something?

-Got binoculars?

-Yeah, it's a puma, Christina.

Absolutely 100% puma. OK.

This is great for filming.

Give me the radio.

Rodrigo calls in Justine,

who is two miles away searching on a different mountain track.

-'Rodrigo, how are you getting on? Over.'

-We just spotted a puma.

Quick. It's just here.

'Perfect.'

OK, we're on our way. Let's go. Let's move on.

The challenge now is to stick close to the puma.

With luck, Justine will get there in time

to film its behaviour at night.

In the Magellan Strait,

Gordon is hoping to solve the mystery

of what brings a pod of humpback whales

so close to shore at night.

There's so much about these animals that we don't know,

so much about them that we'll never know

and the reason is because most of the things they do

are done in complete darkness.

Gordon is relying on his thermal camera to see in total darkness,

but there's no guarantee

his technology will even detect the whales.

This has never been attempted before.

we're answering some questions, we're learning new stuff

and we're only able to do this

because of the technology that we're using.

This camera, it's a thermal camera, so it sees heat sources.

Humpbacks are incredibly well insulated.

They've got a thick, thick layer of blubber,

so it may well be that humpbacks

actually don't give off a temperature signal.

They might be the same temperature as the water. We just don't know.

This is the first time anyone's ever tried

to use this technology to find these animals.

Within minutes, the camera begins to pick up

unusual activity in the water.

Oh, there you go! There you go. You can actually see...

Ohhh! You can see its tail splashing in the water there.

That's interesting - there's this huge cloud of white vapour,

and the reason it's white is because it's hot.

It's hot breath being expelled from these huge lungs.

And it shows up much, much warmer than the ambient water.

Now, you see that?

Oh! Great.

Huge tail splashes and clouds of water coming up from the surface,

not just from it slapping its tail, but from its blowhole as well.

We came out looking for behaviour,

and this is not at all what I expected to see.

From this distance, Gordon can only speculate what the whales are doing.

It may be a way in lower light conditions

for whales to communicate to each other,

to let them know precisely where they are.

That sound, that huge, thunderous sound of the tail

slapping on the surface of the water,

will carry literally for miles.

But they also do it to stun fish.

They'll swim through a shoal and then they'll give a huge tail slap,

literally stunning the life out of the fish,

and then they swim back round and hoover them up.

This is...spectacular.

Humpbacks need to eat one and a half tonnes of food

every 24 hours. They must feed both day and night.

But what brings a pod of humpback whales close to shore

remains a mystery.

What we've seen at night-time is whales

moving closer in to the coast.

What I'd love to do is to get in

to find out exactly what they're doing.

Look at that! Oh!

In Torres del Paine, the puma team has found their cat.

Now Justine wants to see just how it operates in the dark.

-Hi. Hiya.

-Hello.

Where's the puma, then?

The puma was...

Upwind and high above her position,

a herd of a guanaco are oblivious to the puma's presence.

Yeah. This is a good scenario.

We've got loads of guanacos over there.

Hunting at night dramatically increases

the puma's chance of a kill.

It's going up over the ridge.

By day, it's almost impossible to get close enough

to ambush prey as alert as these guanacos.

At night, the puma's superior eyesight gives it the advantage.

(What's happening, Diego? Are they doing anything?)

Justine fires up her thermal imaging camera

and the puma's heat signature is immediately revealed.

(Got it. I've got it.)

(I'm getting it...I'm getting it. Ah, this is fantastic.)

(She's hunting.)

(Wow.)

She's putting each paw down really carefully.

The darkness here is almost total,

yet the puma is utterly focussed

on its prey more than 30 metres away.

(It's perfectly equipped to be hunting at night like this.)

(It's got great sense of smell and hearing.)

(Even though the moon hasn't come up and it's really dark out there,)

(it can still see very well.)

Guanacos have a highly developed sense of hearing.

The contest is so finely balanced

that the puma must take the guanacos by surprise.

(He's in full hunt mode - it's an amazing sight.)

(This is an absolute gem of a situation.)

(As long as I don't cock it up and the puma doesn't cock it up.)

(Now, who knows what's going to happen?)

(I've no idea.)

The puma is about to make its move.

GUANACOS WHINNY

The guanacos sense the danger, and the hunt is over.

(That was such a shame.)

(It looked like he had got everything right,)

(and suddenly - bang! - they were all going.)

(It makes you realise just how hard it is for a puma to hunt.)

Filming a puma hunt in such detail is a great start for Justine.

George is travelling 2,000 miles north to solve another mystery.

He's come to the Atacama desert.

Well, the Atacama, where we are now, is probably

one of the most inhospitable and dry places on earth.

There are parts of the land here that have never had rain ever

in recorded history. It's that dry.

Almost nothing can survive here,

but one nocturnal mammal is thriving and George wants to know why.

I'm heading to this island,

which is just a short way off the coast,

and it's believed to have a colony of vampire bats,

and that is really what I want to see,

and they're only active, and they only fly,

when it's totally dark.

Oh, dolphin! Look at that. Whoa!

They're right under us.

Vampire bats are one of the most iconic creatures of the night.

And the colony here is truly mysterious.

I want to find out what on earth

a colony of vampire bats is feeding on,

on an island that seemingly has few other animals on it

and it looks pretty inhospitable,

but clearly there's enough there for vampire bats to eat.

To help him, he's calling upon the expertise of biologist

Marcelo Flores and wildlife camerawoman Sophie Darlington.

Everything is actually completely fine.

We've put everything in dry bags so all the kit's protected.

This is a hostile landscape, littered with boulders

and coated with guano, or bird excrement.

I've never been anywhere like this before.

The one thing is just the overpowering stench,

which is just everywhere.

Looking around it's sort of like you've landed on the moon a bit.

It's really desolate - like a lunar landscape.

It's incredibly bleak. Really dry, really arid.

George's first task is to find where the bats are roosting.

They say that the cave with the vampires in it

is actually on the coast, so it's really important

that we find the cave as quickly as we can,

cos if we can't find it now, we won't find it in the dark.

This looks very like the cave.

Yeah.

You're right.

The smell is very different.

That's not guano smell, that's something else. That's...

-HE SNIFFS

-That's not nice.

That really is not a nice smell.

HE COUGHS

That's acrid. That's urea, uric acid,

really intense urine smell.

And the rocks are really slippy with bat droppings.

That's just absolutely thick.

Running down the wall.

Oh, yeah. There's one. Just flew...two.

(Oh, yeah, yeah, yeah. Here.)

There's about eight vampire bats just looking straight at me.

Nine, ten...oh, there's more up there.

This is the first time I've ever seen a vampire bat,

and it's, what? Six feet away from me?

(That is amazing.)

(Oh!)

These tiny blood suckers don't use their eyes to find their victims.

Their eyesight is fairly good, their hearing is good,

they can echolocate,

they have infra-red pits around their face

where they can sense the really hot part of the animal

where the blood flow is highest,

and they have teeth that are just razor sharp,

and they just hack off a flap of skin,

and as the blood wells into it,

they just suck it up with their tongue.

And they have a little groove on their lip here

which they press against the wound,

and, of course, they introduce anticoagulants into the bite

so that the saliva makes the blood flow and flow and flow.

There's no doubting the vampire bat's supreme ability

to locate mammals and extract their blood.

What's eluded biologists is why this colony chooses to live here.

What are they eating?

What animal are they extracting the blood from?

That's what I want to know.

I think the only way we're going to find out

is if we can catch one and glue a little tracker on its back

and track it to where it's eating,

and then we should be able to film exactly what animal it's feeding on.

The problem is how to catch a bat, as they are roosting out of reach.

George must return at dusk to net one as it leaves the cave to feed.

Back in the Andes, the puma team prepares for dark.

-OK. Ready.

-Ready, ready.

-We're off, we're off.

They've had a good start, filming a puma hunting.

Now, Justine wants to spend more time with this secretive predator.

What we really want to find out is what pumas actually do

during the night, and that's when they do everything

that pumas get up to.

And we're going to need quite a lot of luck.

But we're hoping to see some unique behaviour.

With dusk approaching, their plan is to spot a puma

as it leaves its daytime lair and goes out to hunt.

Bryson has already picked up a trail.

Look. Fresh tracks.

Right here.

There's another one right there. Look at that.

Wow. That's a good one.

Here's a nice paw print right here.

It's big, but it's not huge.

You know, a full-grown adult would be a bit bigger,

about the size of the middle of my hand.

So it's a teenager.

He's been walking right here.

And that's a pretty good span between footprints.

Yeah.

He's a pretty good size, though. He's not little.

We have a puma.

There's a puma. Right here.

(He just came out of the woods.)

(OK, he's walking along the edge.)

(There he is. Wow.)

(He's right there.)

(He's looking.)

(Nobody move. Everybody stay still.)

(There he is. Right there.)

(He's walking in the brush.)

(What's amazing is, he's not making any sound at all.)

(I can't hear him at all.)

(God.)

(But he's an absolute silent hunter.)

Pumas are at their most dangerous

when they haven't eaten for several days.

He's hungry and he's looking for a meal

so I really got to be careful right now.

The last thing I need to do is act like a prey animal.

Under no circumstances can I run.

That's the worst thing to do.

The thing is, you don't hear a puma coming.

If you're lucky, you see it.

Should it choose to,

this puma is more than capable of killing a fully grown man.

(Don't...run.)

Don't run.

He will attack you.

(He's just staring.)

(Wow, God.)

You know, this is the top predator

and you'll be able to watch him walk out of the woods,

look right at me, and not care at all.

(He's walking away.)

That is the most elegant predator I've ever seen.

(What an incredible animal. God.)

Wow. The dark doesn't belong to us.

It belongs to the pumas.

with hearing and smell and vision like his,

he really is the king of the dark.

The team have a cat in their sights.

This is the opportunity they have been waiting for.

So I'll radio Justine and see if she can get him on a thermal camera.

Justine, this is Bryson. Come in.

'Hi, Bryson.'

Can you hear me? Over.

We just found a puma.

We're on our way to you. Over.

Off the coast of the Atacama desert,

George and biologist Marcelo are heading back into the cave

to catch and tag one of the vampire bats

as it leaves the roost to feed.

(Because they're so closely grouped together,)

(I think it'll be quite easy to catch one,)

(cos in the melee, as they fly off,)

(one of them will surely go in the net.)

(That's my theory, anyway.)

Oof!

Took my head off, that one.

-There's a few.

-That one there.

There's one there.

Yeah, and another one flew behind you.

Is it there?

Got it.

Phew.

These bats carry diseases including rabies.

George and Marcelo must take care when handling them.

-Oh! They're very strong, aren't they?

-Yeah.

-You got it?

-Yeah.

-OK.

-OK?

-Yeah.

What an absolute beauty. Now...

-We'll glue it on the back, yeah? About there.

-Mm-hm.

The miniature radio transmitter

is carefully glued onto the bat's back.

That's it. Lovely. OK?

And that should be it.

George must now track the bat across the island

before the transmitter drops off.

This wee chap is the one that hopefully will show us

where he and his mates are obtaining their evening meal,

and who from, which is the key thing.

Is its transmitter working?

Excellent. Yeah. Very nice.

'Yeah, I can hear you good...'

Justine and Rodrigo are on the trail of Bryson's puma.

I see something coming. It was the puma.

Incredibly, the puma passes just metres in front of Rodrigo.

I saw it. I saw it run across the road in front of you.

That was extreme, actually.

I'm nervous now. I'm trembling.

It was really, really near.

It ran off over the hill. Clearly hunting.

And then I heard all the guanacos just alarming...

IMITATES GUANACO

You could hear them all just going.

And we can't see the puma now.

Yeah, you should go very slowly.

-Maybe we should go round.

-Yeah.

Pumas are ambush predators.

With proportionally the longest back legs of any big cat...

..they can leap ten metres through the air...

..and bring down prey with a single bite to the neck.

Wow, we are so near.

There, there, there! There's the puma.

Turn round, look. Turn round.

I can see...I saw eye shine just then.

-Yeah?

-Yeah. There.

By the time they find the puma, it's clear he's been successful.

I think he might have food in there. He's pulling at something.

Pretty sure there was a kill here.

Yeah, he's pulling at something.

See the head going up and down?

Wow. This is incredible. Wonderful.

This is a one-off, unique experience.

(It's absolutely amazing.)

(We are right next to a puma on a kill.)

(Literally...metres away.)

(We are so close, we can just hear him crunching the bones,)

(pulling at the meat.)

He's just completely absorbed in feeding.

Not bothered about us whatsoever.

It's only been possible to capture these intimate moments

of nocturnal behaviour with Justine's specialist cameras.

He's probably going for a snooze.

Do you hear those sounds? He's going...

IMITATES PUMA

(Calling the mum, calling for his mother.)

PUMA SQUEAKS

(Which means we actually should really have a good look round,)

(because if the mother's turning up, we are in trouble.)

There, there, there.

The mother is far larger and more powerful than the juvenile.

It's time for Justine and Rodrigo to leave.

To film natural behaviour, Justine needs a safer way to stay on a kill.

Two thousand miles south, Gordon is making progress.

He's tracked a humpback whale right into the coastline.

We've got a whale right here in against the shore.

I heard a whale blowing right here.

We've switched off the engine to see if we can hear it.

Seems a strange place for a whale to be, so close to shore.

Gordon's hoping to discover why whales come into such shallow water.

But his hopes are dashed.

With a humpback so close to the boat,

it's now too dangerous for him to get in.

Going in with a 35 tonne animal in there, it's a bit scary.

It's dealing with a set of circumstances

it will never have seen before,

and we just don't know how it's going to react,

and we can't take that risk.

Gordon will need to wait until the whale has moved off

before getting into the water to discover what was attracting it.

We should hear it blow if it's close.

Can't see anything.

I don't think there's anything out there.

All right, let's do it.

Finally, the decision to dive is made

as the whale moves away from the shore.

We're going to get into the water here.

There was definitely a whale

right in the place where we were intending to go.

We think it's gone. They are an enormously powerful animal.

If it comes back, I think we just have to get out of the water.

-Happy for me to get in, Richard?

-Yeah, yeah. Good to go.

Here goes.

Even with his lights,

Gordon can only see 10 metres in the gloom.

It's a claustrophobic and disorientating environment.

Beneath the surface lies a thick maze of kelp -

immensely strong strands of seaweed up to 30 metres long.

The closer to shore, the thicker it becomes.

Whatever it is that's attracting the whales

is hidden deep within this impenetrable forest.

Like tentacles, the weed clings to anything

it comes into contact with, ensnaring Gordon at every turn.

He has to abort his dive.

If Gordon is to solve the whale mystery,

he must find another way.

I guessed, when we got into the water at night-time,

there was going to be some problems that we didn't foresee,

and the big problem, the insurmountable problem,

is this kelp.

It's like Sleeping Beauty's forest.

You can't get through it.

It's impossible.

You just get tangled up in it.

Yeah.

Far from a result.

With two days left in the Andes,

Justine still wants to spend more time with a puma.

Her best chance is to stake out a kill.

Condors circling high overhead are a hopeful sign.

We've been seeing lots of condors flying, circling,

just over the brow of this hill,

and that can only mean one thing, that there's a puma kill around.

If Justine is right, then the puma will be resting up nearby,

waiting to return after dark.

This is just going to be fantastic. This is what I've been waiting for.

I can stake it out, I can get the hide in,

the camera on the tripod, and just sit quietly

and hopefully observe some behaviour.

So far we've been driving around on the tracks

and that's been very productive for actually sighting pumas.

But I want to see some behaviour now.

And I want to get to know the personality of this puma.

In the next valley,

Justine discovers the fresh remains of a juvenile guanaco.

Look at that.

That's a really fresh kill.

You can see where it's been bitten into around the neck,

just beneath the jaw.

It's opened up the guts,

but nothing's been taken from the legs or the chest.

I mean, most of the meat's still left on it.

So this cat's going to want to come back here.

Moving back to higher ground,

Justine prepares for the puma's return.

I mean, it's essential that I'm here and ready before it gets dark,

cos that's when the puma's going to be on the move,

so I've got this rather alarming pop-up hide.

This is going to be it.

This is going to be home for the next 12, 14 hours.

I just have to have a bit of luck now.

Justine has filmed big cats in the wild for over 20 years,

but has only captured glimpses of pumas.

Now, for the first time,

she is hoping to spend the whole night with this elusive cat -

documenting its natural behaviour around a kill.

Just changed from the daytime camera to the night-time camera.

And there's a puma out there.

Wow. It's right on the kill.

Already. It just goes to show, doesn't it,

that the moment it started getting dark, there came the puma.

It's starting to feed. Excellent.

I can see that he's a male.

So strong, the way he's just pulling at that guanaco.

He's walking away. Ah, there he is. He's lying down.

And this is beautiful, to see this puma just feeding.

And now he's just cleaning himself.

It's amazing just seeing this behaviour.

This is everything Justine hoped for.

She will keep watch all night,

her camera ready to capture footage never seen before.

Back off the coast of the Atacama desert,

the vampire bats have left their roost to begin a night of feeding.

It seemed to me that the bats, when they left the cave,

turned left, so we're now heading along the island in that direction,

so if my hunch is right, they should be over here.

Using the VHF receiver,

George and Marcelo hope to track the bats to their victim.

-Got it.

-Have I heard something?

-Yeah.

Yeah? There, there.

Very faint.

Marcelo has identified the signal coming from George's tagged bat.

At first it was very faint,

but it's a lot stronger now, a "beep...beep...beep".

And as long as you follow the bleep,

then you'll end up hopefully right at the bat.

Following the signal for over a mile,

George is getting closer to discovering

where the bats are going to feed, and on what.

That's very strong now.

HONKING

Sea lions. I can hear them.

I can hear them. Look.

We may be one step closer to solving the mystery.

Sea lions are a perfect food source for vampire bats.

Now George must get close enough to the colony to see them in action.

Further south, Gordon is getting closer to solving

the puzzle of why the humpbacks are coming so close to shore.

I thought I heard something back that way.

There's a humpback fairly close by.

I can't see it yet. I just heard it breathing.

Right here, look - whale here.

Oh, you can see his pectoral.

He's going to come up again.

Got a humpback whale just in front of us, less than 25 metres away.

The whale is deep inside the kelp forest

that entangled Gordon earlier.

The camera reveals that despite the current,

the whale is not moving.

It can't be feeding. The kelp is too dense.

But the whale has deliberately chosen to be here -

and Gordon has a theory why.

What could be happening is that the humpback whales in this area

go into the kelp to rest.

Imagine the effort constantly trying to deal with these currents.

To save that effort,

they go in towards the shore and wrap themselves up in the kelp.

Humpbacks are active day and night,

expending vast amounts of energy, so they need to sleep.

But for all whales, sleep is a challenge.

Humpback whales never truly sleep,

they shut down one half of their brain at a time.

For a humpback whale, breathing is a conscious effort.

They have to think about every single breath.

For us, it's an automatic response.

Hear that big puff?

That humpback is saying, "I have to breathe now,"

so they can't afford to go to sleep entirely.

They close down one half of their brain, rest that half,

wake up that half, shut down the other side,

and that way they get a full night's sleep.

(Oh, wow!)

Holy schmoly. Look at that.

Whoa, whoa, whoa! Incredible.

By wrapping themselves in the kelp, this pod has found

an ingenious way of conserving energy while they sleep.

I think to be this close to a humpback whale

takes your breath away.

There are few animals on this planet

that are as impressive as the humpback whale.

Gordon's night vision camera has finally been able to reveal

what these whales are doing so close to shore.

In the Andes, Justine has been watching the puma for six hours.

Most night-time encounters with these predators are fleeting.

She's lucky to immerse herself in this cat's world.

It's just wonderful using this camera.

I've no lights on, just sitting here in the dark,

so it's not disruptive at all.

I think I'm really going to see exactly

what he wants to get up to with his kill.

But for now, he's just having a snooze.

Big cats spend much of their time sleeping.

The puma only stirs as a storm front begins to move across the valley.

It's gusting at extreme speeds

and I'm not sure whether this hide is just going to blow over.

Oh, my God.

I swear the tent's going to fall in.

Puma's got up - what's he doing?

Can't be hunting. He's still got a good kill there.

Oh, he's chasing something.

Probably just trying to keep warm.

That's great.

For all cats, domestic or wild, play is a serious business.

Strong winds and a clump of dry grass

give the puma a chance to hone his hunting skills.

He's playing with it. Just biffing it.

It's so funny. He just looks like a domestic cat.

It's like a secret little view on his life.

I guess if he does this,

sits here by the kill, just cleaning himself and sleeping,

nothing else can come in.

He's dominating it all night long.

This is the sort of amazing behaviour

that I just wanted to see.

Just the cat alone,

blissfully unaware of it being filmed.

Doing what it does in the night.

I just really feel I'm seeing the true side of the puma.

Oh, it's wonderful.

It's the perfect end to Justine's expedition.

She's seen pumas hunting, feeding and playing -

capturing unique footage of these beautiful animals

and their nocturnal lives.

In the Atacama desert, George has called in

wildlife camerawoman Sophie Darlington.

Her thermal camera will be able to capture the vampire bats feeding.

What we need to do to nail it is see them feeding.

-That would be extraordinary.

-That's it.

George has tracked them to a sea lion colony

on the far side of the island.

It could be a perfect source of blood for the bats.

We're coming down here. Some bats would be awesome.

That would be incredible.

Sophie's night vision cameras should provide the answer.

(Well, we're just waiting for the bats to arrive.)

(We're almost set up now,)

(so any minute now...)

(..the vampires will be flying.)

Soon after George and Sophie arrive,

so do the bats, flitting close to them,

attracted by their body heat.

What have you got? Let's see.

(OK.)

There's a big bull,

and there's been a bat flying around completely harassing him.

Oh, yeah, I can see. Yeah, yeah.

There's two of them now.

Three! There's three of them.

That was a bite.

This is unbelievable. Look at it!

-I knew it was there.

-And there's one at the back.

-There's more than one.

-The bats are all over them.

They're following it, look.

There's a vampire bat...look!

It's just following it up behind it.

It's right on the back!

That's just unbelievable.

So they are feeding on sea lions.

The bats employ a clever strategy

when attempting to feed on an animal many times their size.

They land close by and creep towards an area of flesh

the creature will struggle to defend.

They're attacking from the rear,

and the sea lions know they're there,

and they keep turning their heads up,

and as the sea lion moves, they just keep following it.

And the poor sea lions are being harassed.

I mean, they really are aware of that.

Look at him hopping, George.

It dispels the myth of animals having a quiet sleep at night.

They're not. It's torment! It's absolute torment.

They must be exhausted in the morning.

These bats, they're completely and utterly just going for it.

Oh! Oh! Wow!

One's just been hit by that wave.

I just can't believe what I'm seeing.

Weighing 40 grams, each bat can consume half its own body weight

of blood in a single feed, lasting up to 20 minutes.

Is that a hotspot there? Is that the hotspot?

We can see the wound.

Good grief!

We can see the wound on the flipper.

Only the thermal camera can reveal this extraordinary behaviour.

The bats are going in to the rear end because that's where it's hottest

and you can really see that on the thermal camera. They're very bright,

which means the blood's very close to the surface,

so easy access for the bats. An easy meal, I'd reckon.

To see the wound, the heat signature of the wound

left by a vampire bat on the flipper of a sea lion,

in pitch darkness...

That is just...

That is truly awesome.

It is the last of the team's mysteries solved.

Now we know what's happening.

That's why there's a permanent colony of vampire bats here,

because there's a permanent colony of big, fat,

blood-filled food bags for them.

SEA LION HONKS

It's the end of an incredible six months.

The team have pushed themselves to the limit

to capture unique footage of South America's nocturnal wildlife.

We've seen new species.

We've seen behaviours that haven't been seen by anybody before.

Yes! Got it. Look at that.

Using cutting edge technology,

they have uncovered natural behaviour never seen before.

That's fantastic.

There's a whole night shift of animals going about their business,

doing things that we just never see.

(Wow. She's hunting.)

They have witnessed dramas unfolding in total darkness...

(That's incredible.)

..and started to unlock the secrets of a hidden and mysterious world.

Daytime is a practical desert when it comes to animal activity.

And I suppose we're just beginning to scratch the surface

with new technology to reveal a little bit

of what goes on when it's dark.

Subtitles by Red Bee Media Ltd