0:00:01 > 0:00:05Our favourite pets are among the most amazing animals on Earth.
0:00:07 > 0:00:11They've taken to a domestic life and become our perfect companions.
0:00:13 > 0:00:17But still their wild senses remain intact.
0:00:19 > 0:00:21They may have been tamed for thousands of years...
0:00:25 > 0:00:28..but they were wild animals for millions more.
0:00:33 > 0:00:35Some were smart and supreme predators.
0:00:37 > 0:00:40Others were alert and fleet-footed prey.
0:00:48 > 0:00:52Whatever their origins, they still have astonishing hidden powers.
0:00:54 > 0:00:57They use senses different from our own
0:00:57 > 0:01:00and communicate in ways we could never imagine.
0:01:04 > 0:01:06Take a closer look...
0:01:06 > 0:01:09and discover the true animal sharing your home.
0:01:11 > 0:01:14A creature just a wing-beat from the wild.
0:01:18 > 0:01:19THEY CHIRP
0:01:26 > 0:01:30All our pets possess an array of wild senses,
0:01:30 > 0:01:35and this hamster is about to use his on a secret mission.
0:01:35 > 0:01:38He has waited until the dead of night,
0:01:38 > 0:01:40while the rest of the household is sleeping.
0:01:44 > 0:01:48Although not exactly the best of climbers, instinct drives him on.
0:01:59 > 0:02:01To avoid predators, he travels by night,
0:02:01 > 0:02:05a time when his eyesight comes into its own.
0:02:05 > 0:02:09But he also uses his impressive whiskers to build up a 3D picture.
0:02:33 > 0:02:35He uses sounds pitched above our hearing,
0:02:35 > 0:02:39and his supersensitive nose analyses every smell.
0:02:51 > 0:02:55He uses this information to create a sensory map that in the wild
0:02:55 > 0:02:58would guide him across miles of featureless desert.
0:03:10 > 0:03:13But his navigational equipment doesn't stop there.
0:03:13 > 0:03:17Wherever he goes, glands on his belly lay down a scent that
0:03:17 > 0:03:21acts like a paper trail, allowing him to retrace his steps back home.
0:03:27 > 0:03:31For a burrowing creature, holes are irresistible.
0:03:38 > 0:03:41In a hamster ball, he's astute enough to control direction.
0:04:05 > 0:04:09Although some aspects of our modern world are too challenging
0:04:09 > 0:04:10even for this hamster.
0:04:25 > 0:04:29But his incredible senses can also get him out of trouble.
0:04:40 > 0:04:42Using high-pitched calls that we can't hear,
0:04:42 > 0:04:46he detects the drop by the sound of the returning echoes.
0:04:48 > 0:04:51Disaster averted, he continues his secret mission -
0:04:51 > 0:04:55one he must complete before daybreak!
0:05:05 > 0:05:09For dogs, too, getting out and about excites their wild senses -
0:05:09 > 0:05:13and for such intelligent animals, you can't beat a road trip.
0:05:16 > 0:05:18While we are obsessed with visual landmarks,
0:05:18 > 0:05:21they focus only on scents.
0:05:22 > 0:05:25We have a measly six million smell receptors,
0:05:25 > 0:05:29but a dog's nose contains 300 million.
0:05:40 > 0:05:44They use it to unravel stories about the world around them -
0:05:44 > 0:05:47predictably, most are about food.
0:05:52 > 0:05:5540 times more of their brain than ours is devoted
0:05:55 > 0:05:57to deciphering smells.
0:06:00 > 0:06:03They home in on those with special significance -
0:06:03 > 0:06:06a single chemical, aldehyde, found in blood,
0:06:06 > 0:06:08makes this one-time hunter drool.
0:06:11 > 0:06:14There is a way to bring this smelly world to life.
0:06:16 > 0:06:21Schlieren photography visualises the air currents that carry odours
0:06:21 > 0:06:24and shows the remarkable workings of a dog's nose.
0:06:27 > 0:06:30Dogs breathe out through the side slits in their nostrils.
0:06:35 > 0:06:40As the expelled air rotates, it helps draw more scent into the nose.
0:06:45 > 0:06:50This two-way current helps a dog gather scent almost continuously.
0:06:50 > 0:06:52But that's not all...
0:06:55 > 0:06:58A male can smell a female on heat
0:06:58 > 0:07:01at concentrations of one part in a trillion.
0:07:10 > 0:07:15Licking helps capture more of her alluring scent.
0:07:16 > 0:07:20His tongue takes the odour to a second smell organ in the mouth,
0:07:20 > 0:07:23hardwired to the brain and tuned to these sexual pheromones.
0:07:30 > 0:07:33It's love at first sniff.
0:07:39 > 0:07:44For dogs, being a passenger rivals any wild experience.
0:07:44 > 0:07:47But it can be tinged with disappointment too.
0:07:50 > 0:07:53The streets of Paris may be full of romantic promise...
0:07:56 > 0:07:59..but pet dogs are seldom in control of their destiny.
0:08:07 > 0:08:10Love may be in the air, but it's so rarely fulfilled.
0:08:18 > 0:08:21Cats are much more free to follow their noses,
0:08:21 > 0:08:23and they've been shown to investigate
0:08:23 > 0:08:26several hundred odours each hour.
0:08:27 > 0:08:31And smells can sometimes take them to a drug-fuelled gathering.
0:08:35 > 0:08:40He can detect the scent from catnip in just one part in a billion.
0:08:46 > 0:08:49Just a few bites of this mind-altering plant
0:08:49 > 0:08:52and he falls under its alluring spell.
0:09:00 > 0:09:04Its volatile oils imitate a sexual hormone
0:09:04 > 0:09:06and cause a potent reaction in its brain.
0:09:09 > 0:09:13Eight out of ten adult cats find it totally seductive,
0:09:13 > 0:09:16and the strange response is inherited.
0:09:20 > 0:09:23Even big cats, such as leopards and tigers,
0:09:23 > 0:09:26react in the same intoxicated way.
0:09:31 > 0:09:34For cats, catnip may be a recreational drug,
0:09:34 > 0:09:36but it's totally harmless...
0:09:38 > 0:09:41..although there are always some who overindulge!
0:09:54 > 0:09:57It's not all peace and love.
0:09:57 > 0:10:01Cats are solitary by nature and don't like sharing.
0:10:16 > 0:10:20After about ten minutes, the cats come back down to earth.
0:10:22 > 0:10:26But a cat's nose is not its primary sensory tool -
0:10:26 > 0:10:30its eyes are highly tuned to fast-moving prey.
0:10:39 > 0:10:42Fish are especially mesmerising -
0:10:42 > 0:10:45especially those tantalisingly out of reach.
0:10:48 > 0:10:51Goldfish have their own extraordinary abilities.
0:10:55 > 0:10:59They appeared in China over 1,000 years ago,
0:10:59 > 0:11:02having been selectively bred from wild silver carp.
0:11:05 > 0:11:09Around 250 years ago, the stargazer appeared.
0:11:15 > 0:11:19Legend has it that they were created so that their eyes would
0:11:19 > 0:11:22always be directed in wonder towards the glorious emperor.
0:11:31 > 0:11:35Experiments revealed that goldfish recognise their owners.
0:11:35 > 0:11:40They have surprisingly good memories too - five months or more.
0:11:47 > 0:11:50Their extendable jaw helps suck up food.
0:11:52 > 0:11:56The edible bits are ground up on tiny teeth at the back of the mouth,
0:11:56 > 0:11:58while the rest is spat out.
0:12:08 > 0:12:11The stargazer's protruding eyes are easily damaged,
0:12:11 > 0:12:13so they should only be kept by specialists.
0:12:13 > 0:12:16But goldfish have astonishing powers of regeneration,
0:12:16 > 0:12:19and an injured eye can re-grow.
0:12:21 > 0:12:25Goldfish see "far-red" - a colour we can't see
0:12:25 > 0:12:27that penetrates murky pond water.
0:12:29 > 0:12:32But it's not their only sensory tool - a row of sensors,
0:12:32 > 0:12:36known as the lateral line, pick up water movements.
0:12:40 > 0:12:42The filming technique that visualised airflow
0:12:42 > 0:12:46shows the eddies created by a swimming goldfish.
0:12:55 > 0:12:59These mini-currents are picked up by the lateral line of other fish
0:12:59 > 0:13:02and this helps them swim as a coordinated shoal.
0:13:09 > 0:13:13It detects predators too - a touch sends a warning shockwave.
0:13:21 > 0:13:24Goldfish even use ripples to flirt!
0:13:58 > 0:13:59CAT MEOWS
0:14:02 > 0:14:05Just as our pet fish can detect water currents,
0:14:05 > 0:14:09our favourite pet birds can sense the movements of air.
0:14:16 > 0:14:20A budgerigar responds to surrounding air currents by adjusting
0:14:20 > 0:14:22and controlling her flight.
0:14:29 > 0:14:32Nerve endings at the base of her feathers continually feed back
0:14:32 > 0:14:33the information she needs.
0:14:40 > 0:14:44In this way, she detects and avoids turbulent air...
0:14:54 > 0:14:56..and seeks out rising currents.
0:15:09 > 0:15:13By sensing the air, she maintains flight efficiency.
0:15:13 > 0:15:16And budgies have yet another sensory secret...
0:15:20 > 0:15:23In their courtship, good looks are everything.
0:15:23 > 0:15:27But after her flight, she's too occupied in preening to care.
0:15:29 > 0:15:32But her admirer has ways to get himself noticed...
0:15:33 > 0:15:36She sees more subtleties of colour than we can,
0:15:36 > 0:15:40and she detects ultraviolet too - a colour invisible to us.
0:15:42 > 0:15:46Under UV, his plumage takes on a very different look.
0:15:47 > 0:15:51The yellow pigments in his crown and cheeks absorb UV,
0:15:51 > 0:15:53and the effect is stunning.
0:15:55 > 0:15:58But unless she looks, it's all in vain.
0:15:58 > 0:15:59HE CHIRPS
0:16:01 > 0:16:04He fluffs up his feathers to show off his true colours,
0:16:04 > 0:16:07but she still gives him the cold shoulder.
0:16:09 > 0:16:12It seems every relationship needs a nudge sometimes.
0:16:16 > 0:16:18Now he has her attention!
0:16:18 > 0:16:22Females prefer males that really shine -
0:16:22 > 0:16:27the more his plumage absorbs UV, the fitter and healthier he is.
0:16:27 > 0:16:30She's impressed, and invites him to preen.
0:16:32 > 0:16:36The budgie's sensory world continues under our radar -
0:16:36 > 0:16:39as it does with so many of our pets.
0:16:44 > 0:16:47The wandering hamster is completing his secret quest.
0:16:49 > 0:16:50It's taken half the night,
0:16:50 > 0:16:53but he's found exactly what he was looking for!
0:16:54 > 0:16:57He stuffs his cheeks with as much as he can carry.
0:17:10 > 0:17:11And he can carry a lot!
0:17:26 > 0:17:29But there's still one remaining challenge -
0:17:29 > 0:17:32to get back to his nest.
0:17:36 > 0:17:37It's no mean feat.
0:17:40 > 0:17:44By using the mental map he created on his outward journey,
0:17:44 > 0:17:46he sets off in the right direction,
0:17:46 > 0:17:49and soon picks up the scent trail he previously laid.
0:17:53 > 0:17:57It's then a matter of following his nose to his cage.
0:18:04 > 0:18:08Wherever a hamster lives, there's no place like home.
0:18:14 > 0:18:18And, like all homes, there is always room for improvement.
0:18:24 > 0:18:28His pouches are designed to keep their contents bone dry -
0:18:28 > 0:18:31his new bedding is as fresh as when gathered.
0:18:32 > 0:18:36Soon, thanks to his wild senses, this escapologist will be
0:18:36 > 0:18:40tucked up in his newly-made bed with his owner none the wiser.
0:18:42 > 0:18:46Hamsters can go about their business unnoticed,
0:18:46 > 0:18:49but some pets demand a more hands-on approach.
0:18:51 > 0:18:55Anyone who owns a horse is in a unique relationship.
0:18:55 > 0:18:58At its heart are the signals and senses a horse uses in the wild.
0:19:03 > 0:19:07When a child grooms her pony, she unconsciously gives a message
0:19:07 > 0:19:09all horses understand.
0:19:11 > 0:19:15The moving brush mimics the teeth of another horse,
0:19:15 > 0:19:17and it's a sign of friendship.
0:19:19 > 0:19:23Horses only groom close relatives or their very best friends.
0:19:32 > 0:19:36Nibbling the base of the neck lowers the heart rate,
0:19:36 > 0:19:37and has a calming effect.
0:19:43 > 0:19:48Friendships create harmony in a herd, but take time to maintain,
0:19:48 > 0:19:51so horses rarely have more than three lifelong friends.
0:19:59 > 0:20:02To become a successful human friend
0:20:02 > 0:20:05requires being in tune with a horse's wild ways.
0:20:06 > 0:20:09When a mare's about to give birth,
0:20:09 > 0:20:12her knowing owner often separates her from the herd -
0:20:12 > 0:20:15as a prey animal, she feels vulnerable at this time.
0:20:17 > 0:20:19She waits until there is no-one around,
0:20:19 > 0:20:22just as wild horses wait until there are no predators.
0:20:27 > 0:20:31She then prepares the ground for the birth.
0:20:36 > 0:20:40It's a dangerous time for the mare - foals are born fully formed
0:20:40 > 0:20:43and can be difficult to deliver.
0:20:45 > 0:20:48In the end, it happens quickly.
0:20:54 > 0:20:57In these first precious moments, she learns his smell
0:20:57 > 0:20:59and creates a lasting bond.
0:21:03 > 0:21:06She knows he must get to his feet as quickly as possible -
0:21:06 > 0:21:08wild predators could be lurking.
0:21:13 > 0:21:16He has to take his first steps within minutes,
0:21:16 > 0:21:19and become fully mobile over the next few hours.
0:21:24 > 0:21:27SHE GRUNTS
0:21:40 > 0:21:44He even tries to run - a vital survival skill.
0:21:50 > 0:21:55As he suckles, he bonds to his mother's distinctive scent.
0:21:59 > 0:22:02Soon, the world outside beckons -
0:22:02 > 0:22:06he's ready to test out those fragile legs.
0:22:27 > 0:22:28As his confidence grows,
0:22:28 > 0:22:31he practises kicking imaginary predators.
0:22:52 > 0:22:55Young foals must quickly learn the rules governing horse society -
0:22:55 > 0:22:58even rolling has its own etiquette.
0:23:04 > 0:23:07Foals must roll after their mother.
0:23:10 > 0:23:13There are even rules on dealing with flies -
0:23:13 > 0:23:15an annoying problem through the summer months.
0:23:32 > 0:23:36To fight the plague, horses are equipped with fly-whisks,
0:23:36 > 0:23:40but they are most useful for helping others, such as her foal.
0:23:47 > 0:23:49So the mothers are driven to distraction
0:23:49 > 0:23:53while their foals are kept relatively fly-free.
0:24:09 > 0:24:14The foals must learn that it's horse manners to stand end to end.
0:24:17 > 0:24:20He might not have grown the perfect fly-whisk yet,
0:24:20 > 0:24:22but at least he's making the effort.
0:24:33 > 0:24:36Learning to empathise is important for making friends -
0:24:36 > 0:24:39a vital skill for herd life.
0:24:46 > 0:24:49Horses have been human companions for 10,000 years,
0:24:49 > 0:24:51but they're not the only herd animal
0:24:51 > 0:24:54with a long history of domestication.
0:24:57 > 0:25:00The high Andes of South America.
0:25:02 > 0:25:04GUINEA PIG SQUEAKS
0:25:04 > 0:25:06Here, guinea pigs still greet their owners
0:25:06 > 0:25:08with a chorus of anticipation -
0:25:08 > 0:25:11a ritual that goes back 7,000 years.
0:25:16 > 0:25:19They are the most vocal of all our pets,
0:25:19 > 0:25:22and when food's on its way, they can hardly contain themselves.
0:25:25 > 0:25:29They also pogo with excitement - a habit known as "popcorning".
0:25:37 > 0:25:40Although guinea pigs are eaten on special occasions,
0:25:40 > 0:25:42they're valued like pets,
0:25:42 > 0:25:45and are even credited with magical healing powers.
0:25:57 > 0:26:00They came from a wild animal known as a cavy,
0:26:00 > 0:26:03and organise themselves into small herds,
0:26:03 > 0:26:05just like their wild relatives.
0:26:15 > 0:26:19A harem of several females is watched over by a dominant male.
0:26:23 > 0:26:26Every chattering call has meaning.
0:26:28 > 0:26:31This bubbling means they're enjoying themselves -
0:26:31 > 0:26:33it's most often made while eating.
0:26:40 > 0:26:44But, when they're cross, they let everyone know.
0:26:50 > 0:26:52They make warning calls too.
0:27:00 > 0:27:03And the male purrs seductively when wooing a female.
0:27:10 > 0:27:14But guinea pigs breed so readily, most are already pregnant,
0:27:14 > 0:27:16and don't easily fall for his charms.
0:27:19 > 0:27:21If she's not in a romantic mood,
0:27:21 > 0:27:23she'll gladly give him the run-around.
0:27:45 > 0:27:47Perhaps because they're so chatty,
0:27:47 > 0:27:50guinea pigs are now popular the world over.
0:27:50 > 0:27:54But, keep a male and female together and the inevitable happens.
0:27:57 > 0:28:00Her young are born fully developed,
0:28:00 > 0:28:03and giving birth to such large babies can be a challenge.
0:28:12 > 0:28:17The male attends the birth - an unusual habit for rodents.
0:28:27 > 0:28:29This moment has rarely been filmed
0:28:29 > 0:28:32and such paternal interest is quite a revelation.
0:29:00 > 0:29:02Her baby is born in an amniotic sac,
0:29:02 > 0:29:06which his mother bites through to allow him to breathe freely.
0:29:26 > 0:29:28Soon, three young make an appearance,
0:29:28 > 0:29:32all with fully functional senses, and ready to run from predators.
0:29:35 > 0:29:39In the wild, such active youngsters could easily get lost.
0:29:41 > 0:29:44But this new father has a caring side.
0:29:47 > 0:29:52He looks for any that have strayed and sends them back to their mother.
0:29:59 > 0:30:02But there's another reason the male attends the birth.
0:30:02 > 0:30:05Guinea pigs can become pregnant almost immediately,
0:30:05 > 0:30:09and he's perfectly positioned to make the most of the opportunity.
0:30:14 > 0:30:17A mother's smell, sounds and nurturing
0:30:17 > 0:30:20give her young a sense of security and show them how to behave.
0:30:22 > 0:30:25So, what happens if your mum doesn't want you?
0:30:28 > 0:30:31This puppy was rejected by his mother at birth,
0:30:31 > 0:30:35but he's had the good fortune to be adopted by a cat.
0:30:37 > 0:30:41Her mothering hormones are so strong she accepts him as her own.
0:30:45 > 0:30:47The puppy was born on the same day
0:30:47 > 0:30:50and he happily adapts to his new family.
0:30:59 > 0:31:04But kittens live by different social rules, even when they suckle.
0:31:05 > 0:31:08They nametag teats with their own individual scent,
0:31:08 > 0:31:10and return to it each time.
0:31:12 > 0:31:16This simple rule maintains peace and harmony during feeding time.
0:31:21 > 0:31:24But for dogs, pack life requires fighting for your share
0:31:24 > 0:31:26in the rough and tumble of competing mouths.
0:31:31 > 0:31:35This puppy breaks all of the cats' social conventions.
0:31:35 > 0:31:38His wild instincts express themselves,
0:31:38 > 0:31:42despite his unusual family.
0:31:42 > 0:31:43KITTENS MEOW
0:31:52 > 0:31:56Ultimately, the puppy's needs and his foster mum's nurturing feelings
0:31:56 > 0:31:58overcome any differences...
0:31:58 > 0:31:59for now.
0:32:02 > 0:32:07But as adults, these top predators will differ in almost every detail.
0:32:12 > 0:32:16When a cat drinks, he uses a refined technique.
0:32:17 > 0:32:20The rough upper side of his tongue curls downwards
0:32:20 > 0:32:23to pick up the liquid using surface tension.
0:32:26 > 0:32:28It pulls the column of milk up into his mouth
0:32:28 > 0:32:30without making any mess at all.
0:32:49 > 0:32:52A solitary hunter can afford to take his time -
0:32:52 > 0:32:55it's a different matter when you hunt as a pack.
0:33:10 > 0:33:14A dog also pulls a column into his mouth,
0:33:14 > 0:33:17but, unlike cats, he shapes his tongue into a ladle
0:33:17 > 0:33:19to slosh more liquid in.
0:33:22 > 0:33:24For pack animals,
0:33:24 > 0:33:28beating your rivals to a drink is more important than cleanliness.
0:33:32 > 0:33:35X-ray shows how the milk is thrown backwards
0:33:35 > 0:33:37at five times the force of gravity,
0:33:37 > 0:33:40and his mouth shuts like a trap as it is swallowed.
0:33:53 > 0:33:54It might be effective,
0:33:54 > 0:33:57but it's far messier than the cat.
0:34:01 > 0:34:04The two predators could hardly be less alike,
0:34:04 > 0:34:07but those brought up together still find ways to communicate.
0:34:09 > 0:34:13This cat scent-marks his canine pal by rubbing him,
0:34:13 > 0:34:15just as he would another cat.
0:34:20 > 0:34:23But cats choose their moments of affection,
0:34:23 > 0:34:25and independence soon shows itself.
0:34:27 > 0:34:31Cats are the only pet that hunts independently,
0:34:31 > 0:34:33and he's well equipped for the part.
0:34:37 > 0:34:42Rat sounds are above our hearing, but well within the cat's range.
0:34:42 > 0:34:46And his superb night vision pierces the gloom.
0:34:53 > 0:34:58Sensory hairs on his paws test each step, so as not to make a sound.
0:35:02 > 0:35:05His gaze never leaves his prey.
0:35:22 > 0:35:24Just like their wild counterparts,
0:35:24 > 0:35:27housecats stalk as close as they can.
0:35:34 > 0:35:35He freezes.
0:35:36 > 0:35:39Any movement will trigger the attack.
0:35:44 > 0:35:46Something has to give.
0:35:54 > 0:35:56But this rat bites back!
0:35:57 > 0:35:59CAT SCREECHES
0:36:05 > 0:36:10Despite formidable senses, even wild cats miss four times out of five.
0:36:18 > 0:36:22Dogs rarely get to hunt, but their senses are still razor sharp.
0:36:27 > 0:36:30And they combine natural skills with intelligence.
0:36:34 > 0:36:37A well-fed dog looks for somewhere to bury a bone,
0:36:37 > 0:36:39just as he would in the wild.
0:36:44 > 0:36:47But he's smart enough to know he's being watched...
0:36:53 > 0:36:55..and chooses somewhere out of sight.
0:37:04 > 0:37:05Caching food is common among wolves
0:37:05 > 0:37:08as they hedge their bets against leaner times.
0:37:16 > 0:37:20They remember their hideaways, and return to them when hungry.
0:37:27 > 0:37:30But dogs rarely retrieve their buried treasures,
0:37:30 > 0:37:33and this one won't ever get the chance!
0:37:41 > 0:37:44In our world, the wild and the domestic are so mixed up,
0:37:44 > 0:37:47dogs often make some fundamental errors.
0:38:00 > 0:38:02Burying bones, even in the wrong place,
0:38:02 > 0:38:05is one of a dog's favourite natural pastimes.
0:38:11 > 0:38:14But carrying sticks is even more popular.
0:38:14 > 0:38:17In the wild, they bring food back to their young,
0:38:17 > 0:38:20and the instinct to carry is still there.
0:38:27 > 0:38:31Now, they even retrieve sticks from water just for the fun of it.
0:38:39 > 0:38:43Once out, human companions need to move away fast.
0:38:49 > 0:38:53In a single shake, he can lose 70% of the water.
0:39:02 > 0:39:05But he must rotate his body fast enough to fling it from his fur.
0:39:14 > 0:39:18Shaking starts at his head, but the energy wave travels down his body.
0:39:21 > 0:39:25His skin and fur whip the water away as the shake changes direction.
0:39:37 > 0:39:41The force at the hair tips can reach 70 times that of gravity.
0:39:55 > 0:39:58Small dogs must shake faster than larger dogs
0:39:58 > 0:40:00to achieve the same spin-dry result.
0:40:03 > 0:40:05Stand nearby and you're in for a soaking!
0:40:10 > 0:40:12It's not just dogs that can make a mess.
0:40:18 > 0:40:22Place a buck rabbit in a new cage, and it's best to stand well back.
0:40:27 > 0:40:30He makes himself at home by spraying his scent everywhere.
0:40:34 > 0:40:38He also scent-marks with his cheek glands
0:40:38 > 0:40:40and spreads his aroma by digging.
0:40:45 > 0:40:48His actions make perfect sense among wild-living rabbits.
0:40:55 > 0:40:57On Rabbit Island in Japan,
0:40:57 > 0:41:00feral pet rabbits live a near-natural life
0:41:00 > 0:41:02a whisker away from human visitors.
0:41:14 > 0:41:17The same scent-marking behaviour goes on here.
0:41:17 > 0:41:20Any strange new objects are immediately marked
0:41:20 > 0:41:22so they become familiar.
0:41:22 > 0:41:26Males spray females as they compete with other males.
0:41:36 > 0:41:40But, with so much competition, it's every buck for himself.
0:41:50 > 0:41:53Fights get quite heated - they're not such cuddly bunnies now.
0:42:28 > 0:42:30But the winners get the chance to mate.
0:42:38 > 0:42:41Even though some need time to get the hang of it!
0:42:47 > 0:42:50After mating, the doe prepares the nest,
0:42:50 > 0:42:52gathering bedding from wherever she can.
0:42:59 > 0:43:03But, for the very best nest lining, she needn't look far.
0:43:03 > 0:43:06Nothing beats a blanket of fur.
0:43:10 > 0:43:14Any pet given the chance to live naturally
0:43:14 > 0:43:16soon expresses their wild instincts.
0:43:18 > 0:43:22Cats on this Japanese island live a semi-wild existence,
0:43:22 > 0:43:25but in higher numbers than ever found in the wild.
0:43:28 > 0:43:32A wild tomcat has just a few females in his territory,
0:43:32 > 0:43:36but here, cats are forced together as they scavenge from fishermen.
0:43:38 > 0:43:41They use their full repertoire of catcalls
0:43:41 > 0:43:44during the inevitable squabbles.
0:43:44 > 0:43:45HISSING
0:43:48 > 0:43:52They make over 100 sounds in all, some subtle -
0:43:52 > 0:43:53some not so subtle!
0:43:53 > 0:43:55CAT YOWLS
0:43:56 > 0:43:57CATS HISS
0:43:59 > 0:44:01As they scuffle over feeding rights,
0:44:01 > 0:44:04young cats are at a disadvantage and are often chased away.
0:44:09 > 0:44:12Cats don't expect to share their food.
0:44:12 > 0:44:16In nature they hunt alone, and what they catch is theirs.
0:44:21 > 0:44:24This kitten is allowed to push her luck so she may be a young relative.
0:44:24 > 0:44:27But cats seldom give up a meal.
0:44:33 > 0:44:37Most look for a secluded spot away from competitors,
0:44:37 > 0:44:39but they're rarely left alone.
0:44:47 > 0:44:49A hiss is universally understood,
0:44:49 > 0:44:53but cats also know where they are in the social order.
0:45:02 > 0:45:04IT HISSES
0:45:04 > 0:45:08A kitten may hiss all he likes, but in cat society, age comes first.
0:45:17 > 0:45:19Cats also leave scent messages.
0:45:19 > 0:45:22Males spray a pungent note on key landmarks
0:45:22 > 0:45:24to announce their presence.
0:45:29 > 0:45:31They use other scent marks too.
0:45:39 > 0:45:42Glands on the cheeks deposit a unique personal odour.
0:45:46 > 0:45:49They also mark those they regard as friends -
0:45:49 > 0:45:53just as pet cats rub scent on the legs of human owners.
0:45:56 > 0:46:00Scratching applies yet more scent from glands on their feet.
0:46:07 > 0:46:11But some cats prefer not to announce their presence -
0:46:11 > 0:46:13submissive cats bury the smelly evidence,
0:46:13 > 0:46:15just as they do in a litter tray.
0:46:18 > 0:46:21In our homes, cats show their subservience to us
0:46:21 > 0:46:23by hiding their deposits.
0:46:23 > 0:46:26Although few take it to this extreme!
0:46:32 > 0:46:34This cat taught himself the technique.
0:46:36 > 0:46:39If only he could learn to pull the flush!
0:46:49 > 0:46:52With no litter to cover his tracks, he does what comes naturally -
0:46:52 > 0:46:56make the scratching movements that would normally bury his smell.
0:47:08 > 0:47:11Whether scents are concealed or openly flaunted,
0:47:11 > 0:47:13most pets use odours to communicate.
0:47:15 > 0:47:19But no-one uses smell messaging quite like dogs.
0:47:22 > 0:47:25In Cuzco, Peru, pet dogs are allowed to roam the streets at will,
0:47:25 > 0:47:28and can work out what every other city dog is up to
0:47:28 > 0:47:30using their noses.
0:47:33 > 0:47:36Lampposts are irresistible for any dog,
0:47:36 > 0:47:39but this scent-marking is surprisingly sophisticated.
0:47:47 > 0:47:49They act like notes posted around the city,
0:47:49 > 0:47:51and dogs deliberately save up their pee
0:47:51 > 0:47:54to ensure there's enough to go round.
0:48:04 > 0:48:08These messages show who they are and, by the rate the smell decays,
0:48:08 > 0:48:09how recently they've visited.
0:48:11 > 0:48:14Dogs travelling together over-mark each other's scent
0:48:14 > 0:48:16to advertise the size of their pack.
0:48:18 > 0:48:23It allows everyone to keep tabs on the whereabouts of everyone else.
0:48:36 > 0:48:40Dogs that spray higher are more dominant and best avoided.
0:48:45 > 0:48:49But plenty are immediately recognised as friends.
0:48:49 > 0:48:51BARKING AND GROWLING
0:48:51 > 0:48:55In these playful encounters, they associate the dogs they meet
0:48:55 > 0:48:57with the scent marks they've come across.
0:49:12 > 0:49:16Besides scent, there are other ways to find your mates in a big city.
0:49:24 > 0:49:29A barking dog forces air through his vocal cords at over 100mph.
0:49:29 > 0:49:32The sound can exceed 110 decibels...
0:49:35 > 0:49:37..louder than a passing jet.
0:49:40 > 0:49:42Wolves rarely bark,
0:49:42 > 0:49:46so this way of communicating is a product of domestication.
0:49:47 > 0:49:50And dogs produce a complex variety of barks.
0:49:57 > 0:50:01A rapid string of four to five barks is a rallying call.
0:50:04 > 0:50:09Hearing another dog bark increases their heart rate, ready for action.
0:50:13 > 0:50:15DOGS BARK
0:50:20 > 0:50:23It doesn't take long for the message to get around.
0:50:26 > 0:50:30Once they find each other, barking appears contagious.
0:50:39 > 0:50:43One or two short, high-pitched barks are used to greet a friend.
0:50:50 > 0:50:55More continuous, lower-pitched barks alert the pack to a stranger.
0:50:59 > 0:51:03When the talking's over, fights can break out.
0:51:04 > 0:51:07It may look serious, but these skirmishes are mostly for show
0:51:07 > 0:51:09and rarely lead to bloodshed.
0:51:15 > 0:51:18Their bark really is worse than their bite.
0:51:23 > 0:51:27We have only just begun to decipher the dog's hidden messages.
0:51:30 > 0:51:32But, using all their complex signals,
0:51:32 > 0:51:37the dogs of Cuzco have created a parallel world in a human city -
0:51:37 > 0:51:39one known only to them.
0:51:44 > 0:51:48Mutt or pampered pet, street fighter or stray,
0:51:48 > 0:51:51the dogs use their natural abilities
0:51:51 > 0:51:54to sort out their differences and find ways to get along.
0:51:57 > 0:52:00They live in a secret world of communication,
0:52:00 > 0:52:04even though, at the end of the day, most have human homes to return to.
0:52:08 > 0:52:10Living together is all about communication,
0:52:10 > 0:52:14and for horses, herd life would be impossible without it.
0:52:17 > 0:52:21In the Camargue in France, the behaviour of semi-wild horses
0:52:21 > 0:52:24shows why they make such perfect human companions.
0:53:01 > 0:53:05A dominant mare leads a herd of several females and their offspring.
0:53:05 > 0:53:07This willingness to be led
0:53:07 > 0:53:10is the reason a horse responds so readily to our bidding.
0:53:14 > 0:53:17The lead mare takes them to a dust-bathing spot -
0:53:17 > 0:53:20an important part of their daily routine.
0:53:23 > 0:53:26The leader rolls first.
0:53:26 > 0:53:29As foals, they learnt that there's a strict order
0:53:29 > 0:53:31to even the simplest activity.
0:53:37 > 0:53:40Prey animals always need someone on watch.
0:53:40 > 0:53:45The stallion's role is to protect the herd, and he always rolls last.
0:54:10 > 0:54:14The lead mare gains her position through age and experience -
0:54:14 > 0:54:18finding the best food and water is one of her many responsibilities.
0:54:35 > 0:54:39She continually communicates with the herd, mostly using her ears.
0:54:44 > 0:54:47They point towards a horse she's trying to identify,
0:54:47 > 0:54:51but she also uses the position of her ears to convey her feelings.
0:54:55 > 0:54:5716 muscles control each ear,
0:54:57 > 0:55:00allowing subtle changes of expression.
0:55:00 > 0:55:03If they're flopped down, it means she's relaxed and happy.
0:55:03 > 0:55:06When she's interested in something, she pricks them forward.
0:55:14 > 0:55:17And she pins them back when she's annoyed.
0:55:17 > 0:55:21If that doesn't produce the required reaction, she follows with a charge.
0:55:25 > 0:55:27Just pinning back the ears
0:55:27 > 0:55:29is usually enough to get the herd moving.
0:55:32 > 0:55:34As well as responding to ear positions,
0:55:34 > 0:55:37horses are very sensitive to each other's touch,
0:55:37 > 0:55:40and react to pressures too light for humans to feel.
0:55:44 > 0:55:46Riders tap into this sensitivity,
0:55:46 > 0:55:50by a heel pressed against a side, or minute changes of position.
0:55:52 > 0:55:55Although horses communicate in so many different ways,
0:55:55 > 0:55:58it's friendship bonds that lie at the heart of the herd.
0:56:02 > 0:56:05And the very best friends show their affection
0:56:05 > 0:56:07by blowing in each other's noses.
0:56:12 > 0:56:15Young stallions even practise their fighting moves on a friend.
0:56:17 > 0:56:20It's a chance to safely try out techniques
0:56:20 > 0:56:23that one day will be used in earnest.
0:56:34 > 0:56:37But, for now, they're the best of buddies.
0:56:51 > 0:56:53Like all our animal companions,
0:56:53 > 0:56:57horses possess extraordinary wild abilities.
0:56:59 > 0:57:03But all our pets are special in their own unique way.
0:57:07 > 0:57:11They find a way to live alongside us, as part of the family,
0:57:11 > 0:57:13but in a very different world.
0:57:15 > 0:57:18Whether in play,
0:57:18 > 0:57:21or through incredible senses,
0:57:21 > 0:57:24they will always be wild at heart.