Bodies Ingenious Animals

Millions of us love watching the world's wildlife

behaving in strange and wonderful ways.

But what lies at the heart of these extraordinary behaviours?

Can science explain what's really going on?

The latest research from all around the world is increasing

our understanding of animal emotions, relationships,

intelligence and communication faster than ever before.

ROARING

I'm Hugh Fearnley-Whittingstall

and I've teamed up with wildlife experts to travel the globe

in search of the most surprising animal stories.

-Ooh, there, there, there, there!

-Wow! Look at him!

Using the very latest camera technology,

we'll reveal how and why animals do such remarkable things.

And we'll meet the scientists...

Let's go through here.

..who dedicate their lives to understanding

these extraordinary discoveries.

Tonight, we explore the amazing anatomies of some remarkable animals

and the new research that's helping us to understand how

they're perfectly adapted to live in some of the world's

most challenging environments.

Zoologist Lucy Cooke is in Costa Rica to find out

if the sloth's famed laziness could be the key to its success.

Conservationist Giles Clark is in Australia meeting a kangaroo

that's happier climbing trees than hopping through the Outback.

Biologist Patrick Aryee discovers how a fox with super-sensitive

hearing can thrive in one of the harshest habitats on earth.

And marine biologist Shanta Barley

reveals the secrets of the world's oddest-looking creature.

But, first, I'm going to find out how one man's incredible

understanding of an eagle's physical abilities

could unlock its potential and help save a species from extinction.

With a wingspan of almost 2.5 metres,

the white-tailed eagle is the largest eagle in Europe.

These supreme masters of the sky have

a sophisticated, high-performance anatomy.

Wings built to soar.

Sharp eyes to spot prey with pinpoint accuracy.

And talons to snatch and grab with power and precision.

Scientists have long thought it would be impossible to teach

a captive-bred eagle to fly and hunt like a wild one.

But professional falconer Jacques Olivier Travers

is defying conventional wisdom.

He believes he can train eagles born in captivity

to harness the full potential of their anatomy

and master the vital survival skills

for a successful return to the wild.

I'm meeting Jacques Olivier at his aviary in the French Alps,

where he's about to introduce me to his top student.

-This is Victor.

-Wow! He's very happy to see you.

-Oh, yeah, yeah, yeah.

-Whoa! Off he goes!

-Yeah, no problem.

'Seven-year-old Victor is part of a captive-breeding programme

'and has already been trained to make short flights to a food reward.'

Ooh-hoo! Extraordinary.

I just felt the wing beats going across my head there. Such power.

Yeah, it's a very powerful bird.

You've got quite a few different types of eagle here,

but I know the white-tailed's really special.

Why is this such a special bird for you?

I discovered this bird in a book.

I said, "Wow! I've never seen this bird. I want to see one."

And I had to wait for a long time, more than 20 years,

to see my first one.

But when I discovered this bird,

I fell in love with him and I thought,

"I have to do something for this bird because it disappears

"because of us, because we kill all of them."

In the wild, they're skilled at using their magnificent

biology to hunt prey.

But, historically, the hunters became the hunted.

Seen as a threat to livestock in Britain and in France,

the white-tailed eagle was wiped out in both countries

by the early 20th century.

Now the only white-tailed eagles in France are in aviaries or zoos.

Here he comes!

Ooh-hoo! That's amazing!

'To fly in the wild, Victor must be able to glide and soar in the wind.

'That's lesson one of Jacques Olivier's basic training.

'And it's based on the principle that for a man to teach an eagle

'to fly, he has to think like an eagle and fly like one, too.'

A bird who is born in captivity

knows how to go from Point A to Point B.

But to use the pheromone, to use the wind, to use the mountains,

everything, the parents teach him.

And the paraglider is the best thing for that.

-Do you feel like a bird yourself? More bird than human?

-Yeah. Exactly.

And what is amazing, it's for three, four weeks,

when you start to fly, I'm better than him.

But, after one month, they fly so well that I can't follow them.

A tiny camera in a harness on the eagle's back gives

Jacques Olivier an amazing insight into his rookie's flight.

Well, the first time you're on the back of a bird,

you can feel what he feels. You can see what he...

Almost like you're riding on the back of an eagle. It's incredible.

Yeah.

Once an eagle has mastered the art of basic flight,

lesson two is learning how to hunt.

Tell me what makes him such an effective hunter.

Yeah. You can see it's a large bird. He has amazing sight.

He can see his prey more than 2km away.

He has such big and powerful talons that

-he can kill fish or rabbits, ducks, geese.

-Geese?

-He could take on a goose?

-Yeah, of course.

He has been created for hunting.

If Jacques Olivier can teach a captive eagle

to use its extraordinary anatomy to hunt successfully,

then maybe it could be returned to the wild.

But for a man to teach an eagle to hunt

is even harder than teaching him to fly.

The babies will see their parents catch a fish and they will,

just because they see it, try to do the same thing.

-So, it's imitation behaviour...?

-Imitation behaviour.

-They learn to do what their parents are doing visually.

-Exactly.

You, presumably, have not swooped down like a bird and grabbed a fish

-off the water?

-You're right.

-You've had to do it in a different way, little by little?

-Yeah.

Small pool, bigger pool, lake and small piece of fish,

real fish, live fish. It's different steps.

Victor's not quite ready yet to hunt live fish in a big lake,

but Jacques Olivier is going to show me his progress

using bait thrown in the water.

He got that all right.

'It might not look much, but in slow-motion,

'we can see the level of precision Victor has learnt.'

Oh, beautiful!

That was great. He really picked it up with his talons

as though it was a fish.

It's a sophisticated movement.

He has to control his wing movement, his leg movement,

the talon movement in the same second. It's very quick.

So, Victor can catch fish for himself now?

He can catch fish, live fish, in a training pool,

but the last step will be live fish in a big lake.

Because when he knows to do that,

he don't need me and he will come back to the wild.

But even if Victor can master the art of hunting,

he still has to pass lesson three to ensure he can survive in the wild.

He has to learn advanced flight,

in the toughest part of an eagle's natural habitat - the mountains.

Up here, Victor must be able to cope with treacherous strong winds

and other extreme weather conditions.

We'll join him again later when he takes on the ultimate flying test.

BIRDSONG

4,000 miles away,

Giles Clark's in Kenya on the trail of the hippopotamus.

Here, a research project is revealing why one of the planet's

largest vegetarians is the vital life-force of many African rivers.

If ever there was an animal with an image problem, it's these guys.

Weighing the same as your family car,

but with the attitude of a 32-tonne truck,

the hippopotamus is said to be the most dangerous animal in Africa.

But that hasn't stopped ecologist Dr Doug McCauley

from studying them for the last five years.

-Wow!

-Yeah. This pod, Giles, is probably about 25 animals.

It's only because of Doug's expertise

that we can get this close to the hippos.

LOW GRUNTING

There they go, Giles. That's your welcome here, to the hippo pods.

-Such an incredible noise!

-Yeah, I know.

-So, what does that mean?

It's definitely communication, right?

So they're telling each other that I'm here.

They're also communicating about threat. So, right now, you and I.

-They're a little worried...

-They've got nothing to worry about with us.

Well, not me, anyway.

Well, they're letting each other know that there's something strange

here, on the river bank.

There's a hippo over here doing a yawn display.

But those yawns are not about waking up.

The yawn is designed to show everyone who's boss

by displaying their ivory tusks.

The hippos only use their tusks in fights.

But they are no use for eating.

That job falls to their 60cm-wide lips

and the huge molars at the back of their mouths.

The hippos spend all day here, seemingly doing nothing.

But Doug's incredible research

has shown that this is far from the case.

While the hippos wallow,

they are playing a role that's supporting the whole ecosystem.

To find out how, we're joining Doug on a mission

to see the unique way that hippos eat.

To feed, hippos split up from the group and travel down the river.

When they find a suitable spot,

they will leave the water to get to their favourite food - grass.

And to avoid the harsh African sun,

they prefer to graze under the cover of darkness.

As night falls, we get into position.

Our plan is to monitor the hippos

with a newly-designed thermal camera that can film in the dark

in a way that Doug's never been able to see before.

It detects the heat from mammals' bodies up to six miles away.

This tool is amazing.

One of the reasons why there's just so little known about the hippo

is because it's so hard to see them at night.

You wouldn't want to be traipsing around

-in that scrubby vegetation at night looking for them.

-No.

-Whoa-whoa! There, there, there, there! OK?

-Wow, look at him!

We spot three hippos.

-Look at the light.

-Yeah. So it almost looks like she's blotchy.

Yeah. It sort of looks like camouflage, almost, doesn't it?

First time I've seen this in a thermal camera.

It could be that you get scarring on the hippos

-because all these tusk marks.

-When they fight.

And so the scars are really heating up

because there's so much more circulation going into those wounds.

That's the only thing I can think of.

Rather than heading into the bush to graze...

..something spooks them

and they disappear back to the safety of the water.

Hippos aren't the only ones having a midnight feast.

-So, hang on a minute, I think we have a hippo here...

-Yeah, OK.

Oh, wow, look!

An hour later, we get what we're after.

Hidden in the trees, the camera picks up some hippos feeding.

This is what they're really good at.

Their extremely wide mouths means they graze in a way

that is very different from other herbivores.

It's nothing at all to do with the teeth, it's all lips.

They're using those big, horny lips to grab grass there, rip it...

You see its head goes back and forth?

Yeah, it goes backwards and forwards.

Grabbing, plucking and pulling

as the hippo sways its head back and forth,

cutting that grass down

like a putting green in a golf course, right?

The hippo's unique way of eating means they can consume

a staggering 50 kilos of grass a night.

Five times what a cow could eat.

It literally has its head down the whole time.

-These guys are like vampire lawnmowers.

-Heh-heh!

So this is the hidden world of the hippo.

Here we were just watching them sleep all day,

now the animals really actually come alive.

Yeah.

The hippos feed for an incredible seven hours straight.

And it's what happens next

that makes them the unsung heroes of Africa.

What goes in must come out.

Hippos produce up to 27 kilos of dung a day.

This is what really gets Doug going.

Oh, watch, watch here!

Boom!

-OK, see that shower of dung?

-He really showers it.

And they have a very special way of spreading this dung far and wide.

They wag their tails.

And the males have an unusual adaptation

that gives this muck-spreading an extra boost.

Hippos have a backward-facing penis,

probably the weirdest thing about the hippo, right?

So this backward penis shoots the spray of urine up

and then he's got a loose, blobby, gooey bit of dung

shooting out of his rear.

All of that gets mixed together with this paddle-like tail

and then it splatters everywhere.

But this is no laughing matter.

Through his research, Doug has discovered

that hippo dung has remarkable properties.

It's so rich in nutrients,

it acts as a superfood for life in Africa's rivers.

The dung become a really important stimulus of life, almost,

if you will, into this whole food web.

You lock that piece in and the stuff at the bottom

begins to sort of work and grow. And then you have herbivores

that are eating up the algae that grows in the river

and then fish eating these herbivores. Next thing you know,

you have fish eagles swooping down, catching and eating fish.

So, so much of that life sort of springing forth

from the back of the hippo.

So, it seems we really must reconsider

this ruffian of the river banks.

Thanks to Doug's research, we should now see hippos

as nature's lawnmowers and fertilisers.

Their nutrient-rich dung produces food for fish and insect larva

that live in the rivers, which, in turn, become food

for other animals all the way up the food chain.

So, in this way, hippo dung drives the river ecosystem.

And there is no doubt that Africa would be

a very different place without them.

Now, back in the UK,

Lucy Cooke is at Blackpool Zoo to meet the marine biologists

who've been investigating how one of the ocean's most effective

predators catches its prey in pitch-darkness.

CHEERING AND APPLAUSE

Sea lions have been wowing us for years with their showmanship,

but, in the wild, they are even more impressive.

They are incredible hunters

that manage to catch their prey at high speed.

Now, how they manage to achieve this phenomenal feat

has long been a mystery, but now we know the answer.

I'm here to meet the sea lion and the scientists

that have cracked that mystery.

Sea lions are superb swimmers.

Capable of 20mph bursts,

they dive to depths of 180 metres

and often hunt in dark, murky waters.

I'm meeting keeper Alyx Milne and one of her ten sea lions.

THEY LAUGH

So, this is Anya, she's our nine-year-old Californian sea lion.

Hello, Anya! Aw! Big kiss!

I'm going to have a feel of your body.

Oh, wow! That is incredible, how they are just so muscular.

-One slippery, lean muscle, isn't she, basically?

-She is, yeah.

She's built to be so robust and streamline

to be a very good predator.

So in the wild, she would obviously be able to use

her flippers for power, to generate the speed,

and then obviously catching the fish is that neck.

So they have, like, a darting head movement,

where they will dart their neck out at the very last second

to catch that fish and get a tasty bite to eat.

Until recently, scientists couldn't explain

how sea lions were able to hunt at great depths and in total darkness.

How are they able to make that perfectly-aimed strike

without any night vision?

After three years of research,

Alyx and Dr Robyn Grant think they've finally figured it out.

Their revelations came from studying how Anya performs

one of the oldest tricks in the sea lion book.

How does she balance a ball?

The best way to see Anya in action

is to film her with a high-speed camera.

OK, madam, here we go.

Catch the ball. Amazing!

-Well done!

-Good!

-She's starting to test your catching skills.

-Exactly!

More fishy treats for Anya and time for me to look at the footage.

So, here we've got Anya and the ball slowed down five times.

Robyn and Alyx have discovered that when the ball rolls,

it's actually Anya's whiskers that trigger her head to move.

The whiskers always move just before the head moves.

So, it's detecting when the ball is about to roll,

it moves its whiskers and then it moves its head.

How does it translate to their life in the wild?

So, what this is showing you is that

the whiskers are basically always one step ahead.

When it's getting very close to the fish,

and the fish is trying to evade, they're able to sense very quickly

with their whiskers and then change the direction of their body.

So, what we see with the ball is that it senses it very quickly

and then it will respond,

which is very similar to how it would detect a fish, as well.

As the ball rolls, how her head moves to compensate is triggered

by her whiskers feeling when the ball is becoming unbalanced.

In the wild, the whiskers feeling the prey

would trigger the sea lion's body movement

to strike and catch the fish.

It's long been thought that sea lions use their whiskers

in conjunction with their eyes,

but Robyn and Alyx believe that because sea lions

hunt so effectively at depth,

where it's very dark, they're not using their eyes at all.

Balancing is just about possible

if I can watch the object I'm balancing.

But, if I close my eyes, it's game over.

Now, we want to find out if Anya our sea lion is able perform

her balancing act using only her whiskers.

And, in order to do that,

we need to repeat the exercise in the pitch-black.

Now, this is something that Robyn's never done before,

this is totally new research.

So we're really excited to see if she's going to be able to manage it.

As night falls, Alyx leads Anya into position.

Come on, baby girl. Good job.

-First, a fishy treat.

-Can you see it? There we are.

ALYX LAUGHS

For this experiment,

I'm using a camera which can detect infrared light.

-OK, are we ready?

-We're ready.

-All right, lights off.

'As the lights go out,

'it's completely dark - apart from the camera screen.'

OK, here we go, here we go. Will she do it?

'Will she be able to catch the ball in the pitch-black?'

She's actually got the ball! I can't believe it! That's amazing!

'Not only does Anya catch it, incredibly,

'she's able to balance it.'

Just see those whiskers, how they're working.

And you can see that there is movement going on and guiding,

-isn't there?

-It looks very much like what we see in the daytime.

So, they look like they're moving independently.

That is astonishing that she's managing to not only catch

but control the ball. And that really just proves, doesn't it?

I can't see a thing, she can't see a thing, can she?

-She has to be doing that just with her whiskers.

-Yeah, she does.

It's so dark that when Anya throws the ball back to Alyx,

she can't catch it.

This really is like a super-sense, isn't it, with these whiskers?

It's as good as eyes that see in the dark, isn't it?

Yeah. They're using their whiskers as their primary sense.

So they'll be using them like we would use our eyes,

whenever they're in the dark and underwater.

It's a super-sense, a great skill to have.

-And why she's such a fantastic marine predator.

-That's it.

Lucy's ground-breaking infrared experiment

has shown for the first time

that the sea lion's incredible hunting skills

are all down to its remarkable whiskers.

Next, we're heading to the South African desert, where Patrick Aryee

is joining researchers revealing the nocturnal secrets

of one of its most elusive residents.

The magnificent Kalahari.

700,000 square kilometres of arid desert.

With little water and an extreme climate,

the animals that live here have evolved extraordinary abilities

and unique physical adaptations to help them survive.

I've joined scientists Aliza Le Roux and Matt Petelle.

We're on a mission to try and find one of the desert's

most perfectly-adapted animals.

The bat-eared fox.

Bat-eared foxes are one of the hardest animals

in the world to study. They're extremely timid

and only emerge from their underground burrows at night.

But Aliza and Matt have finally found a way to get close to them.

Bribery.

(Oh, there he is! Look!)

Over the last 18 months,

the team have convinced the foxes to trust them,

with the help of some tasty treats.

He's using raisins to lure this fox.

Apparently, they love them.

Don't want to frighten him.

What Matt and the team have achieved is extraordinary.

It's allowing them to finally unlock the bat-eared foxes'

survival secrets.

This fox is right here, right in front of us.

This has been... Isn't he just wonderful?

I feel like a statue right now. I don't want to move.

You can move but very slowly.

OK. How are you?

And this is the first time that people have been able to get

this close to these animals on foot.

It really is quite a special moment.

Yeah.

Hello. This is just brilliant.

One of the adaptations that helps foxes like Baines survive is

hard to miss - their gigantic ears.

And they use these to hunt their prey in the darkness,

which is astonishing considering their favourite prey is about

one centimetre long and, to most animals, completely silent.

See how he had his head up like that?

He's actually listening for the noise of termites.

See? He's just listening.

Baines' ears are incredible.

They can actually pick up the faint crunching sound of

a termite chewing on dry grass.

They act like satellite dishes which they can rotate independently

to gather in sound and amplify them.

We know that they can pick up the termites' sound and that they can

actually pinpoint those locations from 50 metres away, at least.

Incredible.

See how he just sucked them right up?

Yeah, his head's just twitching.

Baines' hearing is far more sensitive than ours.

And scientists believe they can even detect termites moving

several feet under the ground.

-How many termites do you reckon they can get through in a night?

-Oh, wow.

-Thousands, thousands of termites.

-Gosh.

-And they can go

from patch to patch, just spent 15 or 20 minutes in an area,

gobbling them up.

But it's not all about their ears.

When termites are not on the menu, bat-eared foxes are highly

opportunistic, eating other insects, grubs and small mammals.

To be able to find a range of food successfully in the desert,

scientists believe that bat-eared foxes need to be natural

problem solvers, and Matt and Aliza have been putting this to the test.

Aliza's been out at night,

presenting them with a challenging puzzle.

There is the puzzle box.

To get their favourite raisins,

they need to either push a lever or pull a rope.

To the right, you can see where the rope sticks out,

where they can pull on the string and the lever is on the left,

-they could potentially push.

-OK.

There we go. There's a fox. Right, here it comes. Yeah.

Luckily, the fox isn't scared by the unfamiliar object.

When foraging for scarce food in the desert,

it pays to always be inquisitive.

It can smell the food and this is an opportunity that can't be missed.

Straightaway, he's sniffing and smelling the box.

He knows something's going on.

Quite a few raisins in there.

'But will it solve the problem of how to get to them?'

Now he's... Oh, brilliant!

So, that took him about, what, 20 seconds, to hit the first lever.

Yes.

And now he's going in the opposite direction. He's at it.

That is brilliant.

Our clever candidate refused to be outfoxed.

And he's worked out how to get his reward in well under a minute.

-There he goes.

-Brilliant. That's awesome.

So far, Aliza and her team have tested ten bat-eared foxes

and 80% of the time, they managed to solve the problem.

Do you think that maybe your puzzle is too simple?

This is what we are fearing.

But they still had to figure it out and they still...

So far, it looks like they show improvement over time

so there is some sort of learning curve happening.

The fact they are getting faster at solving the problems

is evidence of learned behaviour,

supporting Matt and Aliza's theory that there's more to these

fantastic foxes than a whopping set of ears.

It's what between those ears that is the real secret to this

fox's survival.

On the other side of the world,

Giles Clark is in Australia on the trail of

a rare animal whose anatomy has evolved in a most surprising way.

After 50 million years of evolution, kangaroos and wallabies are

perfectly adapted for a life in the Australian outback.

Five million years ago, a common ancestor of the rock wallaby

here moved into the rainforest and what resulted is now one of

the most bizarre animals on the planet.

It's called Dendrolagus...

..otherwise known as the tree kangaroo.

But how does a kangaroo, with its famously large feet and long

muscular tail, make the leap from living on the ground

to a life in the trees?

I'm on my way to the Tree Roo Rescue Centre in Queensland to meet

Dr Karen Coombes,

who I hope will shed some light on this mysterious marsupial.

-Hi, you must be Karen.

-I am. Giles, nice to meet you.

-Nice to meet you.

Who is the owner of this magnificent tail?

This is McKenzie and he's a little baby tree kangaroo

that we've rescued.

'Karen is now hand-rearing 10-month-old McKenzie.'

Look how adorable he is.

There's a treat. It's your favourite treat.

'It's only when he emerges that I see how different he is

'to a normal kangaroo.'

Amazing.

'His powerful forearms are more muscular than other kangaroos'.

'His tail is bigger, to add balance,

'and his claws longer, to grip branches.'

His legs do resemble a traditional kangaroo's legs but,

at the same time, they are different.

Their back legs are shorter and stockier,

so they can hop on the ground.

'But perhaps the biggest reason why they can climb trees is

'because, unlike their ground-dwelling cousins,

'who can only hop along on two legs, tree kangaroos can move each

'of their back legs separately, giving them greater mobility.

'And for that all-essential grip,

'the pads on their feet act like climbing shoes.

'But a youngster still needs to be taught how to use these

'adaptations to survive.'

They need to learn how to climb.

In the wild, they would be doing it 20 metres up

a tree with their mother.

And they stay with mum for quite some time,

once they're even out of the pouch?

Absolutely. Till they're nearly two and a half

-or three years of age.

-That's a long time.

It's the longest in the kangaroo family.

'But if an orphan is to stand any chance of a life back in the wild,

'they will need a surrogate mother

'who understands their unique biology.'

He's holding my finger. He's very thirsty.

I'm travelling 20 miles, to the edge of the rainforest,

to meet Margit Cianelli,

a former zookeeper who is using her knowledge

of the tree kangaroo's anatomy to prepare orphan joeys for the wild.

-Was that her?

-It could have been.

-I saw a tail then.

-Yeah.

Baby tree kangaroos are orphaned quite often

but over the last 40 years, Margit has rescued over 15 of them

and the latest is making excellent progress in climbing school.

Wow. Hello, sweetheart.

-So, this is Kimberly.

-Yeah. Isn't she gorgeous?

I think she's coming down. She has heard you.

'Kimberly has lived in Margit's house for over two years and

'she has learned how to use her paws to help her slide down a tree,

'tail first, just like a wild tree kangaroo.'

-Good girl, Kimberly.

-Oh!

-Look. This is Giles.

-Hello.

-Isn't she gorgeous?

-Isn't she beautiful?

Almost home.

'Following Margit home with a tree kangaroo on her head

'has to be one of the strangest experiences of my life.

'That is, until we all sit down to tea together.'

Just so surreal. Completely normal, I'm sure,

for you but this is definitely not a typical evening.

'At less than three years old, in the wild,

'Kimberly would still be with her mother so while she spends her

'days in the forest, she spends her nights with her surrogate mum.'

What's her story? How did she end up in your care?

She actually fell into a local swimming hole, out of the tree.

Obviously, she would have drowned. She was only seven months old.

'All attempts to reunite Kimberly with her mother failed,

'so Margit took on the job.'

This is a good exercise.

'She would need to help Kimberly build up her muscles if she

'was to get her back into the trees.

'Once she mastered the basics inside the house, Margit let her loose

'on her own jungle gym - a handmade climbing frame in the garden.

'Margit has also been teaching Kimberly what to eat.'

You're getting your green soup in a minute.

Maybe Giles can give you your green soup.

'This soup is her favourite and provides extra fluid and nutrients.'

Doesn't look like my idea of delicious but...

She likes it that way.

'Now, with a taste of what's good for her,

'she also has to learn what the leaves look like

'and how to eat them.

'Unlike her ground-dwelling namesake, who chews up grass,

'Kimberly's teeth are specially adapted to shear through leaves.'

You are just an eating machine, aren't you?

'And, once fed, it's time to hop up to bed.'

-All right, goodnight.

-Sleep well done. Goodnight.

'A tree kangaroo's sleep pattern is very different to ours.

'In the wild, the low-calorie diet means they have to eat little

'and often, so they only sleep in short bursts of up to

'an hour at a time.

'The next morning, Kimberly is ready to go.'

Hello. Morning.

I'm just fascinated in the way in which gets around.

It's the sort of half walk, half hop.

When she hops, the tail never touches the ground.

See?

'Margit wants Kimberly to spend less time walking on the kitchen floor

'and more time climbing in the trees.

'Eventually, she wants her to return to the wild but before this

'can happen, Margit must be sure Kimberly knows how to use

'her brilliantly adapted body to climb 45 metres,

'up to the forest canopy and find food for herself.'

Good girl.

'We are attaching a tiny, lightweight camera

'to Kimberly's tracking collar.'

OK.

'This will give us the rare opportunity to see the world

'from her perspective and, importantly,

'whether she has what it takes to be wild again.'

Good girl.

OK. We'd better go.

'Off the ground, it becomes clear just how agile Kimberly really is.

'She's perfectly adapted to a life in the trees.'

I'm mesmerised, just how quickly she got up the tree.

She knows how to distribute her weight.

6.5 kilos, and she's just standing literally on twigs.

Look at her balancing.

It's extraordinary.

She's definitely at home in a tree.

She knows where she wants to go.

'To reach the tastiest leaves at the top of the tree,

'Kimberly will have to climb the height of a six storey building

'and way beyond what we can see from ground level.'

We are going to have a look.

'When we review the Kimberly cam footage later that night,

'it reveals the surprising secrets

'of her extraordinary anatomy in action.'

-Look how high she is.

-Yeah.

Almost makes me dizzy when she looks down. Yeah.

Right up in the canopy.

It's her speed along the branches that's so impressive,

compared to her awkward movements on the ground.

Man, she moves around so quickly.

I must say, I'm a bit surprised by that.

-She's more active than I...

-Than you had anticipated?

-Yeah.

'And in the ten hours she was up there, Kimberly proves that

'she has also learned which leaves she needs to eat

'in order to survive.'

-You can see she's eating here. You can hear it.

-It's just amazing.

And she's so fussy.

She picks and sniffs lots of them but only eats certain ones.

'Margit's remarkable understanding of a tree kangaroo's unique

'anatomy has enabled her to teach Kimberly and over 15 other

'orphans the skills that they need to survive in the wild.'

You can't help but feel she's nearly there.

It shouldn't be too much longer and she will be making that

choice to stay out. "I'm going to stay out tonight, Mum."

Yes. And I'm ready for it.

I'm proud of her.

I love her and she can do it all.

Even though she didn't have a real mum.

Oh, she's got a real mum...

-You just don't have a big tail.

-Thanks!

Still in Australia, but nearly 2,000 miles south, lives a very peculiar

animal, whose anatomy has baffled scientists for hundreds of years.

And on hand to investigate its remarkable method of hunting,

is marine biologist Shanta Barley.

I joined ecologist Josh Griffiths on the Yarra River, just outside

Melbourne, to track down the famous oddity that lurks in these waters.

It was once considered a primitive mammal.

But new research is revealing that this animal is the ultimate

predator in the creeks and rivers of Australia.

I'm hoping to find a platypus.

The egg-laying platypus is one of the oddest animals on the planet.

It looks like a cross between a duck, a beaver and an otter.

It's estimated there could be tens of thousands in the wild

but numbers are dwindling

as a result of severe drought and pollution.

They're most active at night and it's almost impossible to spot one,

let alone catch one.

But if anyone can catch one, Josh can.

He's been monitoring the success of the wild population

in this area for six years

and has become a leading expert on these animals.

If you had a good look at the rocks,

you'd see some of the things that platypus are eating.

Some of the insect larvae, small crustaceans, worms.

That's what they're looking for, little invertebrates like that.

Using its bill, the platypus needs to hoover up

a third of its body weight in food every single night.

And it does all of this in the dark.

With the net in place, and night drawing in,

all we can do now is wait.

I've heard that the way that this extraordinary creature hunts

is similar to a shark,

and, as a marine biologist and shark expert, I'm fascinated to know more.

We know that they can detect the electrical impulses of animals

moving underwater, so those tiny little insects that we saw earlier,

their muscle contractions create a minute electrical impulse.

It must be absolutely tiny.

It's tiny, it's something that a lot of our really sensitive equipment

can't even pick up.

After six hours, we finally spot movement in the net.

We got anything? We've got something!

I tell you what, I tell you what...

-There he is.

-It's the most amazing thing. He's holding on, isn't he?

Yeah, they're really strong little creatures.

And that is a little male.

We finally got one.

'To prevent him from getting stressed,

'we put the platypus in a bag.

'And while we record his size, weight and general health,

'it's an opportunity for me to get a close look at his remarkable bill

'which detects these electrical signals,

'allowing him to hunt so effectively in the dark.'

-So he's just poked his bill out of the hole in the bag.

-Oh, wow.

-Can I touch it?

-Yeah, it's very different to what people expect.

Oh, my gosh.

It's not hard like a duck's bill, it's actually quite soft to touch.

Wow. It's so soft.

You can see the little pores that are all through the bill.

They're very fine.

-There's thousands of them across the bill.

-Yeah.

'Around 40,000 tiny bumps speckle the bill.

'These are the receptors that detect minute electrical currents.

'This is how the platypus can pick out a single worm wriggling

'on a rock in a pitch-black running river.'

And what's really jumping out at me is the concentration is really high

on the edges of the bill,

and that's exactly what you get in the hammerhead shark.

With that really weird head, they also have electro-receptors, really,

in high densities right on the edges of the head.

'Astonishingly, this bill contains more than ten times the number

'of electrical receptors as the hammerhead shark.'

So, in some ways,

a platypus is actually a more effective hunter than the shark.

Well, I like to think they're superior, anyway! OK.

'With the checkup complete,

'it's time to return this supreme hunter to the river.'

-Let's let him get back to doing what he does best.

-Yeah.

'I've examined the platypus's bill...'

There he goes!

'..but I've yet to see it in action.' Go on, go on!

So, I'm heading to Healesville Sanctuary,

a haven for threatened, native-Australian species

40 miles from Melbourne.

It's home to a female platypus called Yamacuna.

So acrobatic.

It's feeding time for Yamacuna. On the menu, blood worms.

The blood worms are alive, so they're emitting electrical signals.

When Yamacuna detects those signals,

she shuts down her eyes and her ears and lets her bill take over.

It might look like haphazard snuffling for food,

but this is precision hunting.

Although her eyes and ears are closed,

her bill's electro-receptors come into play.

As she swings her head from side to side,

she's casting a 3-D invisible net.

It picks up the worms' electrical signals.

Yamacuna's bill also detects the minuscule pressure waves

produced by the wriggling worms.

As the intensity of the electrical signals

and pressure waves increases,

she knows exactly how close the worms are.

And this allows Yamacuna to strike with deadly accuracy.

A few minutes is all it takes

to track, locate and eat hundreds of worms.

For me, the comparison with sharks is fascinating.

Both detect electrical signals and pressure waves.

The platypus even has similar body movements

to a hammerhead shark when hunting, swaying its head from side to side.

The shark needs sight and smell to home in on its prey.

But, amazingly, the platypus hunts without these senses.

Just like the shark in our oceans,

the platypus is master of its environment.

Thanks to its extraordinary bill, it's the perfect predator.

9,000 miles away, zoologist Lucy Cooke

is in the Costa Rican jungle

where new research is revealing that the sloths' famed laziness

could be the secret to its survival.

These are four-month-old baby sloths, and they'll become

one of the most successful animals in the jungle once they grow up.

These babies are learning to climb on a rocking chair,

which is genius, because it mimics the movement of a tree.

I've studied these eccentric animals for over five years

and we really shouldn't underestimate them.

So, a lot of people think that sloths,

because they're so slow and lazy,

that they are somehow evolutionary losers.

But, actually, sloths are extremely successful.

Sloths are secretly one of the most abundant mammals

in the Costa Rican rainforest.

New research is revealing the extraordinary adaptations

behind their success.

Professors John Pauli and Zach Peery,

and their team of sloth specialists, are carrying out

one of the biggest ever studies of this little-known creature.

Oh, there!

That is so cool. Literally lying in a tree, having a nap.

Just like a sloth should be.

It is just about the most chilled out-looking animal

you've ever seen in your life.

One of the sloth's key survival tricks is what it eats.

John and Zach discovered that because they do so little,

for their size, sloths need to consume less calories

than any other mammal.

The amount of energy a sloth needs to live

on a day is really, really low.

-It's about 140 kcal per day.

-Wow!

That's like the same as a packet of crisps. That's, like, nothing.

Even though the leaves they eat have very little nutritional value,

it's not a problem for the sloth.

Everything about them is perfectly evolved

to live off this tiny amount of energy.

This is really like the classic sloth pose,

this hanging upside down like this.

They eat upside down, they sleep upside down,

they give birth upside down.

And their hair even grows backwards

so that the rain will just drip off them.

This is the most energy-efficient way to be,

because they're hanging, they're just using these muscles

in order to hang on.

But the sloth's clever tricks don't end there.

By lounging around all day, high in the trees,

sloths are safe from ground predators like jaguars,

but they're still vulnerable to aerial hunters like the harpy eagle.

'But, again, sloths have found a solution.'

It's coming down to see us!

'They're green.

'Which means they merge with the trees.

'And this camouflage is the result of a strange relationship

'between the sloth and a tiny creature hidden in its fur.'

Hello, mister.

Wow! It's a male. Oh, wow!

Have you given this one a name?

-992 is the number of his radio.

-Really?

We don't have a name for him.

-What about Cyril?

-Cyril works.

-Yeah.

-You want to hold him?

-Yeah, wow. Fantastic.

Cyril is covered in a particular kind of moth.

These moths are only found in sloths. They're found nowhere else.

They depend entirely on the sloth for their entire existence.

The moths depend on the sloth for all their home comforts and food.

And, for a long time, it was assumed that it was only the moths

that benefited from this arrangement.

But, thanks to John and Zach's recent discovery,

we now know there's something in it for the sloth, too.

When these moths die,

they actually fertilise the fur within the sloth

and they create nitrogen

that helps the algae that you see on their fur to grow.

-The moths themselves are like making compost?

-That's right.

-That helps keep the sloth green.

-That's exactly right.

The more moths that inhabit a sloth's fur,

the greener and more camouflaged it can become.

This clever relationship means they don't have to outrun predators,

they simply disappear.

These ingenious adaptations

means sloths are thriving in the rainforest,

all without lifting a finger.

He's not in a hurry.

He walks a little way, takes a rest, and he walks a bit more.

And I think us busy, bipedal apes

have probably got quite a lot to learn from them.

About spending less energy.

So far, we've had new insights into the amazing ways

animals adapt to their environments.

And we've seen how some of those adaptations can be crucial

for the planet.

And, with more knowledge of an animal's biology,

we can look after them better,

and help ensure their future survival.

Teaching a captive animal the secrets of survival in the wild

is a tough challenge for conservationists.

I'm back in the French Alps to see how one man's understanding

of an eagle's amazing anatomy

is taking him closer to his dream of returning it to the wild.

Falconer Jacques Olivier Travers believes that,

after nine months of training,

his white-tailed eagle Victor is almost ready to be freed.

Victor's mastered lesson one, the art of basic flight.

And he's well on the way with lesson two, how to hunt.

But before he can become a truly wild eagle,

Victor must prove he can use his highly-tuned anatomy

to complete lesson three,

advanced flight at high altitude.

We're in the ski resort of Morzine,

where Victor's on a warm-up flight ahead of his final challenge.

He flies easily down the sheltered slope.

But his future will depend on whether he can master the skills

to navigate the changes in wind speed and direction

in the open mountains.

Up here, in wild weather, mistakes could be fatal.

We need to take him up to 1,500 metres.

This is the very limit of the eagles' natural range.

-Everything all right there?

-I think so.

-Very good.

-Where shall we put him down?

-Yeah...

Jacques Olivier has trained Victor to follow him wherever he goes.

But, eventually,

the eagle will have to face this ultimate flying test alone.

By skiing quickly away from him, Jacques Olivier knows that Victor

will have to face up to these very tough conditions.

And if that's not enough for a student eagle to contend with,

he'll have the added challenge of having to avoid

the overhead cables of the ski lift.

It may all be too much to ask for today.

Hup, hup!

Here he goes.

But Victor launches his 4kg body into the air

using the sheer power of his wing beats for lift

and the primary flight feathers at the tips of his wings

for balance and direction.

Once up, Victor stretches his wings to glide horizontally,

enabling him to use as little energy as possible.

To cope with the changes in air pressure,

he controls his flight, making small, finely-tuned adjustments

to his wing feathers and even the angle of his head.

Now, as you can see, the wind is bad. It's difficult for him to stay.

He looks like he knows he's doing!

Yeah, you can see that he flies so slowly because the wind is bad,

he has to control his flight. It's good, it's good.

But the descent will be the toughest challenge of all.

Air currents become unstable the closer to the ground he gets.

And ski lift cables are everywhere.

Victor must make increased adjustments to control his flight.

He'll need this control if he's ever to catch prey

in this tough environment.

Yeah, he's coming back now, it's perfect.

Hup! Victor, hup!

Even in these conditions, Victor's able to slow himself down

from a 60 mile an hour dive

and land precisely on Jacques' hand.

-Hey! Victor!

-Nice work, Victor.

Yeah, yeah, nice work.

Because, today, as you can see,

it's not very good weather conditions for flying.

At the top of the mountain the wind was bad,

he was pushing down but he worked hard to turn

in bad weather conditions to follow us.

-Now he's ready to go into the wild, for sure.

-Really?

-Yeah.

-So he's got to that point in his training with you

that he's as strong a flier as he needs to be to survive?

Yeah, and now for flying, for hunting, he's perfect.

Introducing captive-bred animals back into the wild

has to be one of the hardest things in wildlife conservation.

There are just so many different challenges

to identify and then overcome.

But when there's a man who's prepared to go the extra mile

and a bird who's prepared to follow him up every mountain,

then I don't think it's hard to believe that a few years from now,

there could be wild white-tailed eagles flying in the Alps again.