Secretive Creatures Pets - Wild at Heart

Our favourite pets are among the most amazing animals on Earth.

They've taken to a domestic life and become our perfect companions.

But still their wild senses remain intact.

They may have been tamed for thousands of years...

..but they were wild animals for millions more.

Some were smart and supreme predators.

Others were alert and fleet-footed prey.

Whatever their origins, they still have astonishing hidden powers.

They use senses different from our own

and communicate in ways we could never imagine.

Take a closer look...

and discover the true animal sharing your home.

A creature just a wing-beat from the wild.

THEY CHIRP

All our pets possess an array of wild senses,

and this hamster is about to use his on a secret mission.

He has waited until the dead of night,

while the rest of the household is sleeping.

Although not exactly the best of climbers, instinct drives him on.

To avoid predators, he travels by night,

a time when his eyesight comes into its own.

But he also uses his impressive whiskers to build up a 3D picture.

He uses sounds pitched above our hearing,

and his supersensitive nose analyses every smell.

He uses this information to create a sensory map that in the wild

would guide him across miles of featureless desert.

But his navigational equipment doesn't stop there.

Wherever he goes, glands on his belly lay down a scent that

acts like a paper trail, allowing him to retrace his steps back home.

For a burrowing creature, holes are irresistible.

In a hamster ball, he's astute enough to control direction.

Although some aspects of our modern world are too challenging

even for this hamster.

But his incredible senses can also get him out of trouble.

Using high-pitched calls that we can't hear,

he detects the drop by the sound of the returning echoes.

Disaster averted, he continues his secret mission -

one he must complete before daybreak!

For dogs, too, getting out and about excites their wild senses -

and for such intelligent animals, you can't beat a road trip.

While we are obsessed with visual landmarks,

they focus only on scents.

We have a measly six million smell receptors,

but a dog's nose contains 300 million.

They use it to unravel stories about the world around them -

predictably, most are about food.

40 times more of their brain than ours is devoted

to deciphering smells.

They home in on those with special significance -

a single chemical, aldehyde, found in blood,

makes this one-time hunter drool.

There is a way to bring this smelly world to life.

Schlieren photography visualises the air currents that carry odours

and shows the remarkable workings of a dog's nose.

Dogs breathe out through the side slits in their nostrils.

As the expelled air rotates, it helps draw more scent into the nose.

This two-way current helps a dog gather scent almost continuously.

But that's not all...

A male can smell a female on heat

at concentrations of one part in a trillion.

Licking helps capture more of her alluring scent.

His tongue takes the odour to a second smell organ in the mouth,

hardwired to the brain and tuned to these sexual pheromones.

It's love at first sniff.

For dogs, being a passenger rivals any wild experience.

But it can be tinged with disappointment too.

The streets of Paris may be full of romantic promise...

..but pet dogs are seldom in control of their destiny.

Love may be in the air, but it's so rarely fulfilled.

Cats are much more free to follow their noses,

and they've been shown to investigate

several hundred odours each hour.

And smells can sometimes take them to a drug-fuelled gathering.

He can detect the scent from catnip in just one part in a billion.

Just a few bites of this mind-altering plant

and he falls under its alluring spell.

Its volatile oils imitate a sexual hormone

and cause a potent reaction in its brain.

Eight out of ten adult cats find it totally seductive,

and the strange response is inherited.

Even big cats, such as leopards and tigers,

react in the same intoxicated way.

For cats, catnip may be a recreational drug,

but it's totally harmless...

..although there are always some who overindulge!

It's not all peace and love.

Cats are solitary by nature and don't like sharing.

After about ten minutes, the cats come back down to earth.

But a cat's nose is not its primary sensory tool -

its eyes are highly tuned to fast-moving prey.

Fish are especially mesmerising -

especially those tantalisingly out of reach.

Goldfish have their own extraordinary abilities.

They appeared in China over 1,000 years ago,

having been selectively bred from wild silver carp.

Around 250 years ago, the stargazer appeared.

Legend has it that they were created so that their eyes would

always be directed in wonder towards the glorious emperor.

Experiments revealed that goldfish recognise their owners.

They have surprisingly good memories too - five months or more.

Their extendable jaw helps suck up food.

The edible bits are ground up on tiny teeth at the back of the mouth,

while the rest is spat out.

The stargazer's protruding eyes are easily damaged,

so they should only be kept by specialists.

But goldfish have astonishing powers of regeneration,

and an injured eye can re-grow.

Goldfish see "far-red" - a colour we can't see

that penetrates murky pond water.

But it's not their only sensory tool - a row of sensors,

known as the lateral line, pick up water movements.

The filming technique that visualised airflow

shows the eddies created by a swimming goldfish.

These mini-currents are picked up by the lateral line of other fish

and this helps them swim as a coordinated shoal.

It detects predators too - a touch sends a warning shockwave.

Goldfish even use ripples to flirt!

CAT MEOWS

Just as our pet fish can detect water currents,

our favourite pet birds can sense the movements of air.

A budgerigar responds to surrounding air currents by adjusting

and controlling her flight.

Nerve endings at the base of her feathers continually feed back

the information she needs.

In this way, she detects and avoids turbulent air...

..and seeks out rising currents.

By sensing the air, she maintains flight efficiency.

And budgies have yet another sensory secret...

In their courtship, good looks are everything.

But after her flight, she's too occupied in preening to care.

But her admirer has ways to get himself noticed...

She sees more subtleties of colour than we can,

and she detects ultraviolet too - a colour invisible to us.

Under UV, his plumage takes on a very different look.

The yellow pigments in his crown and cheeks absorb UV,

and the effect is stunning.

But unless she looks, it's all in vain.

HE CHIRPS

He fluffs up his feathers to show off his true colours,

but she still gives him the cold shoulder.

It seems every relationship needs a nudge sometimes.

Now he has her attention!

Females prefer males that really shine -

the more his plumage absorbs UV, the fitter and healthier he is.

She's impressed, and invites him to preen.

The budgie's sensory world continues under our radar -

as it does with so many of our pets.

The wandering hamster is completing his secret quest.

It's taken half the night,

but he's found exactly what he was looking for!

He stuffs his cheeks with as much as he can carry.

And he can carry a lot!

But there's still one remaining challenge -

to get back to his nest.

It's no mean feat.

By using the mental map he created on his outward journey,

he sets off in the right direction,

and soon picks up the scent trail he previously laid.

It's then a matter of following his nose to his cage.

Wherever a hamster lives, there's no place like home.

And, like all homes, there is always room for improvement.

His pouches are designed to keep their contents bone dry -

his new bedding is as fresh as when gathered.

Soon, thanks to his wild senses, this escapologist will be

tucked up in his newly-made bed with his owner none the wiser.

Hamsters can go about their business unnoticed,

but some pets demand a more hands-on approach.

Anyone who owns a horse is in a unique relationship.

At its heart are the signals and senses a horse uses in the wild.

When a child grooms her pony, she unconsciously gives a message

all horses understand.

The moving brush mimics the teeth of another horse,

and it's a sign of friendship.

Horses only groom close relatives or their very best friends.

Nibbling the base of the neck lowers the heart rate,

and has a calming effect.

Friendships create harmony in a herd, but take time to maintain,

so horses rarely have more than three lifelong friends.

To become a successful human friend

requires being in tune with a horse's wild ways.

When a mare's about to give birth,

her knowing owner often separates her from the herd -

as a prey animal, she feels vulnerable at this time.

She waits until there is no-one around,

just as wild horses wait until there are no predators.

She then prepares the ground for the birth.

It's a dangerous time for the mare - foals are born fully formed

and can be difficult to deliver.

In the end, it happens quickly.

In these first precious moments, she learns his smell

and creates a lasting bond.

She knows he must get to his feet as quickly as possible -

wild predators could be lurking.

He has to take his first steps within minutes,

and become fully mobile over the next few hours.

SHE GRUNTS

He even tries to run - a vital survival skill.

As he suckles, he bonds to his mother's distinctive scent.

Soon, the world outside beckons -

he's ready to test out those fragile legs.

As his confidence grows,

he practises kicking imaginary predators.

Young foals must quickly learn the rules governing horse society -

even rolling has its own etiquette.

Foals must roll after their mother.

There are even rules on dealing with flies -

an annoying problem through the summer months.

To fight the plague, horses are equipped with fly-whisks,

but they are most useful for helping others, such as her foal.

So the mothers are driven to distraction

while their foals are kept relatively fly-free.

The foals must learn that it's horse manners to stand end to end.

He might not have grown the perfect fly-whisk yet,

but at least he's making the effort.

Learning to empathise is important for making friends -

a vital skill for herd life.

Horses have been human companions for 10,000 years,

but they're not the only herd animal

with a long history of domestication.

The high Andes of South America.

GUINEA PIG SQUEAKS

Here, guinea pigs still greet their owners

with a chorus of anticipation -

a ritual that goes back 7,000 years.

They are the most vocal of all our pets,

and when food's on its way, they can hardly contain themselves.

They also pogo with excitement - a habit known as "popcorning".

Although guinea pigs are eaten on special occasions,

they're valued like pets,

and are even credited with magical healing powers.

They came from a wild animal known as a cavy,

and organise themselves into small herds,

just like their wild relatives.

A harem of several females is watched over by a dominant male.

Every chattering call has meaning.

This bubbling means they're enjoying themselves -

it's most often made while eating.

But, when they're cross, they let everyone know.

They make warning calls too.

And the male purrs seductively when wooing a female.

But guinea pigs breed so readily, most are already pregnant,

and don't easily fall for his charms.

If she's not in a romantic mood,

she'll gladly give him the run-around.

Perhaps because they're so chatty,

guinea pigs are now popular the world over.

But, keep a male and female together and the inevitable happens.

Her young are born fully developed,

and giving birth to such large babies can be a challenge.

The male attends the birth - an unusual habit for rodents.

This moment has rarely been filmed

and such paternal interest is quite a revelation.

Her baby is born in an amniotic sac,

which his mother bites through to allow him to breathe freely.

Soon, three young make an appearance,

all with fully functional senses, and ready to run from predators.

In the wild, such active youngsters could easily get lost.

But this new father has a caring side.

He looks for any that have strayed and sends them back to their mother.

But there's another reason the male attends the birth.

Guinea pigs can become pregnant almost immediately,

and he's perfectly positioned to make the most of the opportunity.

A mother's smell, sounds and nurturing

give her young a sense of security and show them how to behave.

So, what happens if your mum doesn't want you?

This puppy was rejected by his mother at birth,

but he's had the good fortune to be adopted by a cat.

Her mothering hormones are so strong she accepts him as her own.

The puppy was born on the same day

and he happily adapts to his new family.

But kittens live by different social rules, even when they suckle.

They nametag teats with their own individual scent,

and return to it each time.

This simple rule maintains peace and harmony during feeding time.

But for dogs, pack life requires fighting for your share

in the rough and tumble of competing mouths.

This puppy breaks all of the cats' social conventions.

His wild instincts express themselves,

despite his unusual family.

KITTENS MEOW

Ultimately, the puppy's needs and his foster mum's nurturing feelings

overcome any differences...

for now.

But as adults, these top predators will differ in almost every detail.

When a cat drinks, he uses a refined technique.

The rough upper side of his tongue curls downwards

to pick up the liquid using surface tension.

It pulls the column of milk up into his mouth

without making any mess at all.

A solitary hunter can afford to take his time -

it's a different matter when you hunt as a pack.

A dog also pulls a column into his mouth,

but, unlike cats, he shapes his tongue into a ladle

to slosh more liquid in.

For pack animals,

beating your rivals to a drink is more important than cleanliness.

X-ray shows how the milk is thrown backwards

at five times the force of gravity,

and his mouth shuts like a trap as it is swallowed.

It might be effective,

but it's far messier than the cat.

The two predators could hardly be less alike,

but those brought up together still find ways to communicate.

This cat scent-marks his canine pal by rubbing him,

just as he would another cat.

But cats choose their moments of affection,

and independence soon shows itself.

Cats are the only pet that hunts independently,

and he's well equipped for the part.

Rat sounds are above our hearing, but well within the cat's range.

And his superb night vision pierces the gloom.

Sensory hairs on his paws test each step, so as not to make a sound.

His gaze never leaves his prey.

Just like their wild counterparts,

housecats stalk as close as they can.

He freezes.

Any movement will trigger the attack.

Something has to give.

But this rat bites back!

CAT SCREECHES

Despite formidable senses, even wild cats miss four times out of five.

Dogs rarely get to hunt, but their senses are still razor sharp.

And they combine natural skills with intelligence.

A well-fed dog looks for somewhere to bury a bone,

just as he would in the wild.

But he's smart enough to know he's being watched...

..and chooses somewhere out of sight.

Caching food is common among wolves

as they hedge their bets against leaner times.

They remember their hideaways, and return to them when hungry.

But dogs rarely retrieve their buried treasures,

and this one won't ever get the chance!

In our world, the wild and the domestic are so mixed up,

dogs often make some fundamental errors.

Burying bones, even in the wrong place,

is one of a dog's favourite natural pastimes.

But carrying sticks is even more popular.

In the wild, they bring food back to their young,

and the instinct to carry is still there.

Now, they even retrieve sticks from water just for the fun of it.

Once out, human companions need to move away fast.

In a single shake, he can lose 70% of the water.

But he must rotate his body fast enough to fling it from his fur.

Shaking starts at his head, but the energy wave travels down his body.

His skin and fur whip the water away as the shake changes direction.

The force at the hair tips can reach 70 times that of gravity.

Small dogs must shake faster than larger dogs

to achieve the same spin-dry result.

Stand nearby and you're in for a soaking!

It's not just dogs that can make a mess.

Place a buck rabbit in a new cage, and it's best to stand well back.

He makes himself at home by spraying his scent everywhere.

He also scent-marks with his cheek glands

and spreads his aroma by digging.

His actions make perfect sense among wild-living rabbits.

On Rabbit Island in Japan,

feral pet rabbits live a near-natural life

a whisker away from human visitors.

The same scent-marking behaviour goes on here.

Any strange new objects are immediately marked

so they become familiar.

Males spray females as they compete with other males.

But, with so much competition, it's every buck for himself.

Fights get quite heated - they're not such cuddly bunnies now.

But the winners get the chance to mate.

Even though some need time to get the hang of it!

After mating, the doe prepares the nest,

gathering bedding from wherever she can.

But, for the very best nest lining, she needn't look far.

Nothing beats a blanket of fur.

Any pet given the chance to live naturally

soon expresses their wild instincts.

Cats on this Japanese island live a semi-wild existence,

but in higher numbers than ever found in the wild.

A wild tomcat has just a few females in his territory,

but here, cats are forced together as they scavenge from fishermen.

They use their full repertoire of catcalls

during the inevitable squabbles.

HISSING

They make over 100 sounds in all, some subtle -

some not so subtle!

CAT YOWLS

CATS HISS

As they scuffle over feeding rights,

young cats are at a disadvantage and are often chased away.

Cats don't expect to share their food.

In nature they hunt alone, and what they catch is theirs.

This kitten is allowed to push her luck so she may be a young relative.

But cats seldom give up a meal.

Most look for a secluded spot away from competitors,

but they're rarely left alone.

A hiss is universally understood,

but cats also know where they are in the social order.

IT HISSES

A kitten may hiss all he likes, but in cat society, age comes first.

Cats also leave scent messages.

Males spray a pungent note on key landmarks

to announce their presence.

They use other scent marks too.

Glands on the cheeks deposit a unique personal odour.

They also mark those they regard as friends -

just as pet cats rub scent on the legs of human owners.

Scratching applies yet more scent from glands on their feet.

But some cats prefer not to announce their presence -

submissive cats bury the smelly evidence,

just as they do in a litter tray.

In our homes, cats show their subservience to us

by hiding their deposits.

Although few take it to this extreme!

This cat taught himself the technique.

If only he could learn to pull the flush!

With no litter to cover his tracks, he does what comes naturally -

make the scratching movements that would normally bury his smell.

Whether scents are concealed or openly flaunted,

most pets use odours to communicate.

But no-one uses smell messaging quite like dogs.

In Cuzco, Peru, pet dogs are allowed to roam the streets at will,

and can work out what every other city dog is up to

using their noses.

Lampposts are irresistible for any dog,

but this scent-marking is surprisingly sophisticated.

They act like notes posted around the city,

and dogs deliberately save up their pee

to ensure there's enough to go round.

These messages show who they are and, by the rate the smell decays,

how recently they've visited.

Dogs travelling together over-mark each other's scent

to advertise the size of their pack.

It allows everyone to keep tabs on the whereabouts of everyone else.

Dogs that spray higher are more dominant and best avoided.

But plenty are immediately recognised as friends.

BARKING AND GROWLING

In these playful encounters, they associate the dogs they meet

with the scent marks they've come across.

Besides scent, there are other ways to find your mates in a big city.

A barking dog forces air through his vocal cords at over 100mph.

The sound can exceed 110 decibels...

..louder than a passing jet.

Wolves rarely bark,

so this way of communicating is a product of domestication.

And dogs produce a complex variety of barks.

A rapid string of four to five barks is a rallying call.

Hearing another dog bark increases their heart rate, ready for action.

DOGS BARK

It doesn't take long for the message to get around.

Once they find each other, barking appears contagious.

One or two short, high-pitched barks are used to greet a friend.

More continuous, lower-pitched barks alert the pack to a stranger.

When the talking's over, fights can break out.

It may look serious, but these skirmishes are mostly for show

and rarely lead to bloodshed.

Their bark really is worse than their bite.

We have only just begun to decipher the dog's hidden messages.

But, using all their complex signals,

the dogs of Cuzco have created a parallel world in a human city -

one known only to them.

Mutt or pampered pet, street fighter or stray,

the dogs use their natural abilities

to sort out their differences and find ways to get along.

They live in a secret world of communication,

even though, at the end of the day, most have human homes to return to.

Living together is all about communication,

and for horses, herd life would be impossible without it.

In the Camargue in France, the behaviour of semi-wild horses

shows why they make such perfect human companions.

A dominant mare leads a herd of several females and their offspring.

This willingness to be led

is the reason a horse responds so readily to our bidding.

The lead mare takes them to a dust-bathing spot -

an important part of their daily routine.

The leader rolls first.

As foals, they learnt that there's a strict order

to even the simplest activity.

Prey animals always need someone on watch.

The stallion's role is to protect the herd, and he always rolls last.

The lead mare gains her position through age and experience -

finding the best food and water is one of her many responsibilities.

She continually communicates with the herd, mostly using her ears.

They point towards a horse she's trying to identify,

but she also uses the position of her ears to convey her feelings.

16 muscles control each ear,

allowing subtle changes of expression.

If they're flopped down, it means she's relaxed and happy.

When she's interested in something, she pricks them forward.

And she pins them back when she's annoyed.

If that doesn't produce the required reaction, she follows with a charge.

Just pinning back the ears

is usually enough to get the herd moving.

As well as responding to ear positions,

horses are very sensitive to each other's touch,

and react to pressures too light for humans to feel.

Riders tap into this sensitivity,

by a heel pressed against a side, or minute changes of position.

Although horses communicate in so many different ways,

it's friendship bonds that lie at the heart of the herd.

And the very best friends show their affection

by blowing in each other's noses.

Young stallions even practise their fighting moves on a friend.

It's a chance to safely try out techniques

that one day will be used in earnest.

But, for now, they're the best of buddies.

Like all our animal companions,

horses possess extraordinary wild abilities.

But all our pets are special in their own unique way.

They find a way to live alongside us, as part of the family,

but in a very different world.

Whether in play,

or through incredible senses,

they will always be wild at heart.