All language subtitles for How Do Animals Do That S02 E04_track3_[eng]

♪♪

Narrator: ANIMALS...

DO THE MOST INCREDIBLE THINGS.

[ GOAT BLEATS ]

LIKE THIS...

AND THIS.

I BET YOU'RE WONDERING,
"HOW DO THEY DO THAT?"

WE'RE REVEALING ANIMALS'
BIGGEST SECRETS, LIKE...

HOW CAN FOUR DOGS
WRANGLE 500 SHEEP?

WHY DO MOTHS FLY INTO FLAMES?

AND WHY DO ROOSTERS
ALWAYS CROW JUST BEFORE DAWN?

THESE WONDERS AND MORE ON...

--Captions by VITAC--
www.vitac.com

CAPTIONS PAID FOR BY
DISCOVERY COMMUNICATIONS

AUSTRALIA IS HOME TO JUST ABOUT

EVERY DEADLY CREATURE
YOU CAN THINK OF...

♪♪

...AND SOME NOT SO DEADLY,
LIKE SHEEP --

OVER 72 MILLION AT LAST COUNT.

THAT'S THREE SHEEP TO
EVERY HUMAN LIVING DOWN UNDER.

HEY!

Narrator:
JUST OUTSIDE MELBOURNE,

FARMER DAVID HAS 500 SHEEP.

THEY'VE BEEN OUT IN THE FIELDS,

AND NOW IT'S TIME FOR EVERY
LAST ONE TO RETURN TO THE PEN.

IT'S AN IMPOSSIBLE JOB
FOR DAVID,

BUT NOT
FOR HIS INCREDIBLE SHEEP DOGS.

THIS IS THE SHEEP-HERDING
DREAM TEAM.

LEADER OF THE PACK IS CHECKERS,

A 13-YEAR-OLD
BORDER COLLIE CROSS,

FOLLOWED BY 4-YEAR-OLD KELPIES
SISCO, PILLAR, AND BLUE TACK...

HOP UP. [ WHISTLES ]

Narrator:
...AND OF COURSE, FARMER DAVID.

HOP UP, PILL. GOOD JOB.

THEY'RE PRETTY KEEN
TO SEE SOME SHEEP NOW, I RECKON.

AREN'T YA?

♪♪

Narrator: THERE ARE 344
OFFICIAL BREEDS OF DOG,

BUT ONLY ABOUT
40 CAN DO WHAT THESE GUYS DO.

THAT'S BECAUSE THEY SHARE
AN INSTINCT FOR PACK HUNTING,

TO HERD PREY BEFORE A KILL.

BUT SHEPHERDS LIKE DAVID
HAVE FIGURED OUT

HOW TO TAP THE DOG'S INSTINCT
AND HIGH ENERGY.

Sleigh:
THE DOGS ARE NATURAL HUNTERS.

IT'S A MATTER OF CURBING
THEIR HUNTING INSTINCT.

YOU TRY AND REDUCE
THE KILLER IN THEM

AND JUST HARNESS
THE HERDING INSTINCT

THAT GOES WITH PACK BEHAVIOR.

[ WHISTLES ] YEAH.

Narrator: DOGS OF THIS BREED
ARE NATURALLY OBEDIENT,

AND FARMER DAVID USES THIS TO
TEMPER THEIR INSTINCT TO KILL.

FROM ONE YEAR OLD, ONCE PAST
THOSE PLAYFUL PUPPY DAYS,

SHEEP DOGS ARE TRAINED TO OBEY
THE LEADER OF THE PACK --

ALWAYS REWARDED FOR OBEYING
THE TOP DOG'S DEMANDS.

THE TOP DOG HERE
IS FARMER DAVID,

AND FARMER DAVID SAYS SHEEP
ARE STRICTLY OFF THE MENU.

[ WHISTLING ]

THE DOGS APPROACH THE 500 SHEEP.

AS THEY DO, THE SHEEP
HUDDLE TOGETHER FOR SAFETY.

IF THE DOGS GET TOO CLOSE,
THE SHEEP WILL SCATTER,

BUT IF THEY HANG BACK TOO FAR,

THE FLOCK CAN SPLIT
INTO SMALLER GROUPS.

♪♪

NEW RESEARCH HAS SHOWN
THAT THE SHEEP DOGS

CONSTANTLY SCOUR THE FLOCK

FOR GAPS
OPENING BETWEEN THE SHEEP.

IF THEY SEE ONE, THEY POSITION
THEMSELVES TO DISCOURAGE

ANY MOVEMENT OF SHEEP
AWAY FROM THE MAIN HERD.

NO DRAMAS.

Narrator: BUT THE DOGS
AREN'T ON AUTOPILOT,

AND FROM THEY STAND,
THEY CAN'T SEE THE WHOLE FLOCK.

[ WHISTLES ]

Narrator:
FARMER DAVID CAN SEE EVERYTHING

AND KNOWS WHERE
HE WANTS HIS SHEEP TO GO.

HE WHISTLES INSTRUCTIONS
TO DIFFERENT DOGS.

TO THE UNTRAINED EAR,

ONE WHISTLE SOUNDS
JUST LIKE THE NEXT...

[ WHISTLING ]

...BUT TO
THE SUPER FINE HEARING OF A DOG,

THE FARMER'S VARIOUS WHISTLES
MEAN DIFFERENT THINGS.

♪♪

WITH A SUBTLE CHANGE
TO THE NUMBER OF WHISTLES,

THE FARMER CAN MAKE
THE DOGS MOVE TO THE RIGHT...

[ WHISTLES ]...AND MOVE TO THE LEFT.

CHANGING THE LENGTH
OF HIS WHISTLE

TELLS THE DOGS TO STOP...

[ WHISTLE ]...OR MOVE FORWARD.

[ WHISTLING ]

Narrator:
THE DOGS AREN'T JUST OBEDIENT.

THEY'RE ALSO GOOD AT MATH --
THE MATH OF SHEEP BEHAVIOR.

TO SHOW WHAT THESE ARE,

FARMER DAVID IS GOING TO
WALK INTO A FLOCK.

IT'S LIKE THERE'S A FORCE FIELD
SURROUNDING HIM,

PUSHING THE SHEEP AWAY.

Sleigh:
IF I GET ANY CLOSER --

SEE HOW THEY'VE KEPT
THAT RING AROUND ME?

Narrator: ACTUALLY,
THIS IS A MENTAL FORCE FIELD

AROUND THE SHEEP.

IT'S CALLED A FLIGHT ZONE.

Sleigh: THE FLIGHT ZONE IS
THE DISTANCE THE SHEEP

WOULD LIKE TO KEEP
BETWEEN YOU AND THEM.

Narrator: GET CLOSER THAN ABOUT
10 FEET TO A SHEEP,

AND IT WILL MOVE AWAY
TO KEEP THAT SAFE DISTANCE.

AND THOSE CLEVER DOGS HAVE
LEARNED TO THINK LIKE A SHEEP

AND USE IT
TO NAVIGATE THE FLOCK.

THE DOGS USE
THE 10-FEET FLIGHT ZONE

TO CONTROL THE DIRECTION
AND MOVEMENT OF THE FLOCK.

AS THEY SPRINT UP AND DOWN
THE REAR OF THE FLOCK,

THEY EDGE INTO THE FLIGHT ZONE
TO FORCE THE SHEEP LEFT,

RIGHT, OR FORWARDS.

Sleigh: YOU'VE GOT TO MASSAGE
THAT FLIGHT ZONE

TO WITHIN A FOOT OR TWO

SO THAT YOU GET THEM
WALKING FORWARD.

♪♪

[ WHISTLING ]

THAT'S GOT THEM MOVING
A BIT QUICKER NOW.

Narrator: NOW FARMER DAVID
NEEDS TO GET THE SHEEP

THROUGH A SINGLE GATE.

Sleigh:
[ WHISTLES ] HERE, HERE.

SO WE'RE CALLING THEM OVER NOW

BECAUSE THE SHEEP
ARE GOING PAST THE GATE,

SO WE'RE CALLING THEM OVER
TO THE RUN-IN SIDE.

[ WHISTLING ] STEADY.

Narrator: MOVING AROUND
THE EDGE OF A FLOCK,

THE DOGS STEER THE SHEEP
TOWARD THE FENCE...

UNTIL ONE FINDS THE GAP IN IT.

THEN, BECAUSE THEY'RE SHEEP,
WHERE ONE GOES, THE REST FOLLOW.

Sleigh: THAT'S IT.

JOB DONE.

Narrator:
AN HOUR AND A HALF LATER,

AND FOUR DOGS AND ONE HUMAN

HAVE COUNTED 500 SHEEP
BACK INTO THE PEN.

♪♪

WE ALL KNOW DIAMONDS
ARE A GIRL'S BEST FRIEND,

BUT OTTERS HAVE
A PASSION FOR PEBBLES.

AND IT'S A LOVE THAT CAN LAST
FOR MONTHS, SOME THINK YEARS.

A CLUE IS IN THEIR DIET.

A SEA OTTER'S LUNCH COMES
TO THE TABLE READY FOR A FIGHT.

♪♪

CLAMS, ABALONE, SNAILS --

ALL HEAVILY ARMORED
WITH THICK, TOUGH SHELLS.

AND SEA OTTERS NEED TO EAT

A QUARTER OF THEIR BODY WEIGHT
OF THEM EVERY DAY.

THAT'S THE EQUIVALENT OF A MAN
DINING ON OVER 30 T-BONE STEAKS.

♪♪

TO CRACK SO MANY HARD SHELLS,

SEA OTTERS HAVE EVOLVED
TO HAVE SUPER TOUGH TEETH.

IN FACT,
THE ENAMEL IN THEIR TEETH

IS OVER 2 1/2 TIMES TOUGHER
THAN OURS.

EXTRA LAYERS OF
A SPECIAL PROTEIN-RICH GEL

PREVENTS OTTER TEETH
FROM CRACKING

AS THEY BITE DOWN ON THEIR PREY.

BUT FOR SOME MEALS,

EVEN REINFORCED TEETH
ARE NOT STRONG ENOUGH.

♪♪

FOR THOSE REALLY TOUGH SHELLS,
THE SEA OTTER USES A TOOL,

AND THE TOOL OF THEIR CHOICE
IS A PEBBLE.

OTHER THAN DOLPHINS,

SEA OTTERS ARE THE ONLY
MARINE MAMMAL THAT USE TOOLS.

BUT THIS TOOL
IS NOT JUST ANY PEBBLE.

IT HAS TO BE HEAVY
AND HARD ENOUGH

TO USE AS A HAMMER
OR AN ANVIL WITHOUT SHATTERING.

IT MUST BE SMOOTH ENOUGH

SO THE SEA OTTER
CAN HOLD IT IN THEIR PAWS

AND SMALL ENOUGH TO KEEP
IN A UNIQUE PEBBLE POCKET

SEA OTTERS HAVE
UNDER ONE OF THEIR LIMBS.

♪♪

IN FACT, WHEN THEY FIND
THE PERFECT PEBBLE,

IT IS SO PRECIOUS

THAT THEY MAY KEEP IT
FOR UP TO A YEAR OR MORE.

♪♪

AND TO IMPROVE THEIR AGILITY
AND DEXTERITY

WITH THEIR FAVORITE TOOL,

SEA OTTERS PRACTICE
BY JUGGLING WITH THEIR PEBBLES.

AND ALTHOUGH NO ONE REALLY
KNOWS WHY, SO DO RIVER OTTERS,

EVEN THOUGH
THEY DON'T USE A PEBBLE

AS A TOOL FOR GETTING TO FOOD
OR HAVE A PEBBLE POCKET.

♪♪

MAYBE OTTERS JUST LIKE JUGGLING.

♪♪

COMING UP...

NIGHT FLYERS
WITH A FATAL ATTRACTION...

THE SECRET BEHIND
THE ROOSTER'S CROW...

AND WHY IS THIS SEA TURTLE
CRYING?

♪♪

♪♪

Narrator: AS NIGHT FALLS
ON A BALMY SUMMER'S EVENING,

MILLIONS OF MOTHS
ARE TAKING TO THE SKY.

AND THEN...

THAT'S GOT TO HURT.

WHY DO THESE
NOCTURNAL NAVIGATORS

ALWAYS MAKE A BEELINE
FOR A BULB?

THEY SEEM TO BE DRAWN TO LIGHT
LIKE MOTHS TO A...

WELL, YOU KNOW.

TO FIND OUT WHY MOTHS HAVE
SUCH A FASCINATION WITH LIGHTS,

WE'VE COME TO A FLORIDA FOREST
IN THE DEAD OF NIGHT,

WHERE MOTH EXPERT ERIC ANDERSON
IS PERFORMING A TEST.

Anderson:
IT'S VERY HUMID OUT.

PERFECT CONDITIONS. NEW MOON.

AND MAYBE WE'LL GET SOME
COOPERATION FROM THE INSECTS.

Narrator: ERIC'S BRIGHT IDEA IS
TO SEE HOW MOTHS REACT

TO THREE
DIFFERENT KINDS OF LIGHT.

FIRST UP,
A TYPICAL WHITE PORCH LIGHT.

ALL RIGHT.

THERE'S ALREADY
A FEW THINGS COMING IN.

MOTHS FLY JUST STRAIGHT TO IT.

Narrator: MOTHS ARE DRAWN
TO THE WHITE LIGHT

BECAUSE OF HOW
THEY'VE EVOLVED TO NAVIGATE

USING THE BRIGHT LIGHT
OF THE MOON.

♪♪

WHEN LUNAR LIGHT

HITS ULTRA-SENSITIVE RECEPTORS
IN MOTHS' EYES,

IT TELLS THEM WHAT'S UP
AND WHAT'S DOWN.

THE SKY IS BRIGHT,
THE GROUND DARK,

BUT MOONLIGHT
ALSO TELLS A MOTH DIRECTION.

BY KEEPING A FIXED ANGLE ON
THE DISTANT SOURCE OF MOONLIGHT,

THE GLOW HELPS THEM FLY
IN A STRAIGHT LINE.

BUT TO A MOTH, THE ARTIFICIAL
WHITE LIGHT ON OUR FRONT PORCHES

APPEARS TO BE THE MOON,
AND THE BUG BECOMES CONFUSED.

SINCE HOUSE LIGHTS
ARE MUCH CLOSER THAN THE MOON,

THE RELATIVE ANGLE CHANGES...

AND BAM, RIGHT INTO THE LIGHT.

THEY BECOME DISORIENTED

AND FLY RIGHT TOWARDS IT
UNCONTROLLABLY.

Narrator: NEXT, ERIC WANTS
TO SEE IF MOTHS ARE CAPTIVATED

BY THIS COOL
BLUE FLUORESCENT LIGHT.

Anderson: HERE WE HAVE
A LOT OF GUYS COMIN' IN.

THIS IS GOOD.

THEY'RE JUST
REALLY ATTRACTED TO THEM.

THEY CAN'T FIGHT IT.

Narrator: THE FLUORESCENT
BLUE LIGHT IS A MOTH MAGNET.

MOTHS AND BUTTERFLIES
ARE ATTRACTED TO BLUE LIGHT

BECAUSE THEIR EYES CAN DETECT

PARTS OF THE LIGHT SPECTRUM
WE CAN'T -- ULTRAVIOLET.

THEY USE THIS SPECIAL ABILITY
TO IDENTIFY MARKINGS ON FLOWERS

THAT CAN ONLY BE SEEN IN U.V.

U.V. MARKINGS ON A FLOWER IS
A SIGN THAT IT CONTAINS NECTAR,

WHICH MOTHS EAT.

Anderson: WHEN FLYING AROUND
IN PITCH DARKNESS

AND THERE'S A LIGHT
IN THE BLUE SPECTRUM,

OR VIOLET SPECTRUM, THEY JUST
COME RIGHT TO THE LIGHT.

Narrator:
SO THE BUGS THINK THE BLUE LIGHT

IS GUIDING THEM TOWARDS DINNER.

THAT'S WHY THE FLUORESCENT
BLUE LIGHT OF A BUG ZAPPER

IS SO EFFECTIVE.

BUT IT'S A FATAL ATTRACTION.

[ ELECTRICITY CRACKLING ]

SO IS THERE A LIGHT
THAT MOTHS ARE NOTATTRACTED TO?

WE'RE ABOUT TO APPROACH A LIGHT

THAT IS ON THE OPPOSITE END
OF THE SPECTRUM,

MORE OF AN ORANGEY YELLOW.

Narrator:
WITH THE WARM L.E.D. BULB,

THERE DOESN'T SEEM TO BE
MUCH BUG ACTIVITY

ON THE BED SHEETS.

SO HERE'S TWO HOUSE FLIES.

Narrator:
AND ANY MOTHS?

Anderson: NO MOTHS.

Narrator:
IN A RECENT TEST,

9,000 INSECTS WERE EXPOSED
TO DIFFERENT LIGHTS,

AND IT TURNED OUT
THE BUGS WERE LEAST ATTRACTED

TO THE WARM L.E.D.

[ DING! ]

AND THAT'S BECAUSE MOTHS
ARE UNABLE TO DETECT LIGHT WAVES

IN THE ORANGE AND YELLOW PART
OF THE VISIBLE SPECTRUM.

AND YOU KNOW WHAT THAT MEANS.

IF YOU DON'T WANT INSECTS
ON YOUR PORCH,

GET A BULB THAT'S
ORANGEY YELLOW, AND IT'LL WORK.

♪♪

ALL RIGHT.

♪♪

Narrator: COMING UP,
WHY DO TURTLES CRY?

AND THE SECRET
TO CLOCKWORK CROWS.

[ ROOSTER CROWS ]

♪♪

♪♪

Narrator:
SEA TURTLES HAVE BEEN GLIDING

THROUGH OUR WORLD'S OCEANS
FOR 200 MILLION YEARS,

ONLY EVER COMING ON LAND
TO LAY THEIR EGGS...

♪♪

...WHERE, TO BE HONEST,
THEY'RE SLIGHTLY LESS ELEGANT.

IN FACT, SEA TURTLES STRUGGLE
SO MUCH OUT OF THE WATER,

IT SEEMS TO BRING THEM TO TEARS.

♪♪

LEGEND HAS IT
THAT MOTHER TURTLES CRY

BECAUSE THEY CAN'T STAND

LEAVING THEIR BABIES BEHIND
ON THE BEACH.

BUT THEY DON'T JUST CRY
WHEN THEY SAY GOODBYE --

THEY CRY ALL THE TIME,
IN THE WATER AND OUT.

SO...

WE'VE COME TO THE LOGGERHEAD
MARINELIFE CENTER IN FLORIDA,

WHERE DR. JUSTIN PERRAULT
CARES FOR INJURED TURTLES.

♪♪

CURRENTLY, WE HAVE ABOUT
10 SEA-TURTLE PATIENTS HERE

THAT ARE REHABILITATING.

Narrator: THIS SAD-LOOKING GUY
IS GAVIN, A TEENAGE LOGGERHEAD

WHO WAS FOUND WITH
A FISHING HOOK IN HIS FLIPPER.

AND THAT ISSOMETHING
TO CRY ABOUT.

HE IS A SUB-ADULT MALE THAT IS
RIGHT ON THE CUSP OF MATURITY.

HE'S NOT COMPLETELY
FULLY MATURE YET.

Narrator:
BUT AFTER SOME TURTLE TLC,

GAVIN IS STILL SUPER WEEPY.

AND A CLUE TO WHY CAN BE FOUND
IN THE TEARS THEMSELVES.

Perrault: THE SECRETION
THAT YOU'RE SEEING

IS THREE TIMES THE CONCENTRATION

OF THE SALT
THAT WE SEE IN THE BLOOD,

AND IT CAN ACTUALLY BE
TWICE THAT OF SEAWATER.

Narrator:
THESE THICK, BRINY TEARS

ARE NEARLY 10 TIMES AS SALTY
AS HUMAN TEARS.

Perrault: WHAT YOU'RE SEEING
WITH THESE TEARS

IS HOW THIS ANIMAL RIDS ITS BODY
OF ITS EXCESS SALT.

♪♪

Narrator: MARINE TURTLES
CONSTANTLY DRINK SALTY SEAWATER.

AND THEIR DIET OF JELLYFISH,
SEA GRASS,

AND ALGAE IS FULL OF SALT, TOO.

WHAT SALT CAN DO IN THE BODY,
IF YOU HAVE TOO MUCH OF IT

AND YOU'RE NOT GETTING RID OF
ENOUGH OF IT,

WHAT WILL HAPPEN IS IT WILL
CAUSE YOUR INTERNAL CELLS

TO SHRIVEL AND POTENTIALLY DIE.

Narrator: MOST ANIMALS
GET RID OF EXCESS SALT

THROUGH THEIR KIDNEYS,

BUT TURTLES TAKE IN MORE THAN
THEIR KIDNEYS CAN COPE WITH.

SO THEY EVOLVED
SPECIAL ORGANS IN THEIR HEAD

TO ELIMINATE THE EXCESS.

Perrault: SO WHAT WE'VE GOT HERE
IS A REPLICA

OF A LOGGERHEAD
SEA-TURTLE SKULL.

YOU'VE GOT YOUR HOLE FOR
THE BRAIN, WHICH IS VERY SMALL,

AND THEN YOU'VE GOT
YOUR TWO ADDITIONAL HOLES.

Narrator: THESE TWO CAVITIES
HOUSE ORGANS CALLED SALT GLANDS.

INCREDIBLY, IN SOME TURTLES,

THEY CAN BE UP TO 20 TIMES
LARGER THAN THE TURTLE'S BRAIN.

BUT THESE REPTILES
DON'T NEED TO THINK --

THEY NEED TO DRINK.

WHEN SEA TURTLES
TAKE IN SEAWATER,

SALT QUICKLY ENTERS
THE BLOODSTREAM.

THIS BRINY BLOOD IS SENT
STRAIGHT TO THE TWO GLANDS.

HERE, EXCESS SALT
IS FILTERED OUT

AND EXCRETED
AS THICK, GLOOPY TEARS.

♪♪

SO THAT MEANS TURTLES
ARE BASICALLY CRYING

EVERY MINUTE OF EVERY DAY
FOR THEIR ENTIRE LIVES.

♪♪

BUT THEY'RE NOT
TEARS OF SADNESS --

THEY'RE TEARS OF SURVIVAL.

♪♪

[ TIGER GROWLS ]

NEXT...

WHY DO ROOSTERS ALWAYS CROW
JUST BEFORE THE CRACK OF DAWN?

[ ROOSTER CROWS ]

♪♪

♪♪

Narrator: 5:00 A.M...

[ ROOSTER CROWS ]

...AND ONE EARLY RISER
IS ALREADY UP AND AT 'EM.

[ ROOSTER CROWS ]

ROOSTERS ARE NATURE'S
ALARM CLOCK,

WHETHER NATURE
WANTS TO WAKE UP OR NOT.

[ ROOSTER CROWS ]

[ ROOSTER CROWS ]

♪♪

THIS HANDSOME GUY IS RORY.

[ RORY CROWS ]

WHEN HE GETS GOING, HE CROWS AT
AN EAR-SPLITTING 100 DECIBELS.

THAT'S AS LOUD AS A JACKHAMMER.

[ JACKHAMMER WHIRRING,
RORY CROWS ]

YOU'D THINK WITH ALL
THIS RACKET, RORY WOULD GO DEAF,

BUT EVERY TIME
HE OPENS HIS BEAK...

[ RORY CROWS ]

...MUSCLES IN HIS EAR CANALS
PARTIALLY CLOSE,

BLOCKING THE SOUND.

THAT'S RIGHT,
RORY'S GOT BUILT-IN EAR PLUGS.

[ RORY CROWS ]

♪♪

ON THIS FARM...

[ ROOSTER CROWS ]

...RORY RULES THE ROOST.

THE REASON HE CROWS SO EARLY
IS SO HE CAN CROW FIRST

TO SHOW THE OTHERS WHO'S BOSS.

[ ROOSTER CROWS ]

ONCE RORY'S FANFARE
HAS BROKEN THE SILENCE,

A COUPLE OF HOURS BEFORE DAWN,

ONLY THEN
CAN THE OTHERS JOIN IN.

[ ROOSTERS CROWING ]

ITS BARNYARD CODE
FOR PECKING ORDER.

SO KING ROOSTERS LIKE RORY
GET UP EARLY

TO BE THE FIRST TO CROW...

[ ROOSTER CROWS ]

...BUT HOW DO THEY KNOW
WHEN IT'S TWO HOURS BEFORE DAWN?

ARE THEY REACTING TO
THE FIRST RAYS OF MORNING SUN?

TO FIND OUT, RESEARCHERS IN
JAPAN KEPT SOME RAUCOUS ROOSTERS

IN A ROOM FOR TWO WEEKS
AND TURNED THE LIGHTS OFF.

♪♪

DESPITE HAVING NO STIMULUS

TO REVEAL
WHETHER IT WAS NIGHT OR DAY,

THEY ALWAYS CROWED
WITHOUT FAIL...

[ ROOSTERS CROWING ]

...TWO HOURS
BEFORE DAWN BROKE OUTSIDE.

THIS TEST PROVED ROOSTERS
HAVE A BUILT-IN BIOLOGICAL CLOCK

SET TO A SPECIFIC TIME.

FROM FUNGI TO BUTTERFLIES,

ALL LIVING THINGS
HAVE GENES IN THEIR CELLS

THAT DICTATE
THE RHYTHMS OF THEIR DAY,

LIKE WHEN TO WAKE...

AND WHEN TO CATCH 40 WINKS.

WHAT THE JAPANESE EXPERIMENT
REVEALED, HOWEVER,

WAS THE ROOSTER'S BODY CLOCK
IS SET TO A 24-HOUR CLOCK.

WELL, 23.8 TO BE EXACT.

AND IT'S SO HARD-WIRED

THAT TAKING AWAY A SUNRISE
CAN'T DISRUPT IT.

SO IT'S RORY'S BIOLOGY

THAT KEEPS HIM
TOP OF THE PECKING ORDER.

[ RORY CROWS ]

IF HE STARTS RUNNING LATE
WITH HIS MORNING CROWS...

[ RORY CROWS ]

...IT TELLS HIS RIVALS
THAT HE'S PAST HIS PRIME,

AND THEY'LL CHALLENGE HIM
TO BE TOP COCK ON THE BLOCK.

♪♪

[ ROOSTER CROWS ]

AND FOR ANYONE WHO THINKS A HEN
MIGHT BE A QUIETER OPTION...

[ HEN CROWS ]

...HENS CROW, TOO.

[ HEN CROWS ]