All language subtitles for Attenboroughs Life in Colour 2of2 Hiding in Colour 1080p BBC EN

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The natural world is full of colours
that we often take for granted.

There are few animals
more brilliantly coloured

than these scarlet macaws.

Animals can use colour for
all kinds of different reasons

and some have colours
that we ourselves can't even see.

But not all colours are what
they seem.

Some animals also use
colours to hide.

Colours that make them disappear.

Colours that create
optical illusions.

And colours that are used

to trick and deceive.

To understand how these
colours work,

we need to see them
from an animal's perspective.

With the help of our specialist
cameras, we can now do that...

..and discover how some animals
have become masters of disguise.

The Indian subcontinent is home to
some truly spectacular animals.

Most, like these peafowl, use colour
to attract attention and the kinds

they've developed are influenced
by the way they see the world.

But flashy colours
can also come at a cost,

and, sometimes, it's better
to remain out of sight.

So, some animals use their colours
to help them hide

and disappear into the background.

One such animal lives here
in the forests of central India.

It's one of the most formidable
hunters on Earth.

A Bengal tiger.

A female.

She is one of the world's
biggest cats.

And remaining out of sight
is not easy

when you are as large as she is.

Her orange and black coat
is crucial to her success.

To have any chance
of catching a meal,

she has to get to within
a few metres of her prey.

She keeps to the cover of the trees

and slowly makes her approach.

She may appear conspicuous
to our eyes,

but not so to these chital deer.

Chital have only two types of colour
receptors in their eyes,

compared to our three, which
means that they are, effectively,

blind to red and orange.

So, to the deer,
the tiger isn't orange at all.

This is how we see world...

..and this is how deer do.

The tiger's orange coat to them
is a muted shade of green,

so it's nearly impossible
for the deer to register.

She creeps closer.

The chital don't see her.

The odds appear stacked in
the tiger's favour.

But the deer aren't entirely
defenceless.

They have help from an unusual ally.

Langur monkeys.

They are known as
"the eyes of the forest"

and their colour vision
is excellent.

Their eyes, like ours, have
three types of colour receptors,

and they can see orange.

MONKEY SCREECHES

SCREECHING ECHOES

The langurs sounded the alarm
before she could get close enough.

If the langurs can easily spot her,
why, then,

is the tiger orange at all?

Why isn't she green?

That's because mammals are unable
to develop green pigments.

So, it seems the next best solution
for the tiger is to have

orange fur, which appears
green to her main prey.

She will have to find a new target.

Down by the water, she finds one.

Sambar deer.

Sambar don't keep company
with monkeys.

They are on their own.

They have the same limited eyesight
as the chital

but ears like satellite dishes.

If she treads on a twig
and it snaps,

the hunt will be over
before it began.

The deer seem to sense danger.

They still can't see her.

WATER SPLASHES

Despite her effective camouflage,

most hunts end like this.

Less than 10% of her attacks
are successful.

But, without her orange fur,
her chances would be even lower.

It is her colours that are key
to her survival.

The Cairngorm Mountains in Scotland.

Here, there are special problems
for the hunted.

Some animals have developed
camouflage of such perfection

that they are virtually invisible
against their surroundings.

But what happens
when those surroundings change?

Well, then, of course,
the animals have to change, too.

These mountains are home
to a particular kind of grouse

called the ptarmigan.

Their mottled brown feathers
make them inconspicuous

among the rocks and heather.

But, in winter, these mountains
are hard places in which to live.

Temperatures drop,

and the land can, overnight,

be covered by a blanket of snow.

Most birds by now have gone south
to warmer parts of the world.

But not the ptarmigan.

When winter comes, they undergo
the most extraordinary change.

They replace their brown feathers
with pure white ones.

They do so for a simple reason -

they must go unnoticed.

They need to hide.

This open habitat
makes the ptarmigan

very vulnerable to predators.

Being the right colour is crucial.

Now they are invisible
even to a keen-eyed eagle.

Ptarmigan are not the only animals
to use this disappearing act.

So does the Arctic fox...

..snowshoe hares...

..and weasels.

All, with the coming of winter,
change their coats

and vanish from sight.

Their transformation is triggered
by the decreasing daylight,

and, over several weeks,

they replace their brown costumes
with white ones.

So, changing colour with
the seasons, for some animals,

is the only way
to avoid becoming a meal.

But many plants, of course,
do the reverse.

In spring, they produce colour

to declare that they are
providing food - nectar.

Bees, and many other insects,
love it.

In spring and summer, they travel
busily from flower to flower,

collecting it.

And, when the bees leave to look for
more, they inadvertently take pollen

with them which then fertilises

the next flowers they visit.

But there's a hunter here that
exploits this relationship.

A crab spider.

She's tiny,

no bigger than a fingernail,

and she is waiting for her prey.

BUZZING

Almost the same colour
as her background,

she's virtually invisible.

No more honey for her!

But, of course, the spider's hunting
grounds are limited.

Not all flowers are yellow.

When she sits on a pure white petal,
she immediately becomes obvious.

She will never catch a bee
while she's so conspicuous.

So, she changes.

She breaks down the yellow pigments
in the outer layer of her skin

to expose special crystals
underneath that act like

tiny mirrors and reflect the light.

It may take a few days,

but she turns from yellow

to white.

Changing colour isn't
the spider's only trick.

There's more to this story
than meets the eye.

Bees can see colours that we cannot.

They can see ultraviolet colours.

As they come in to land on a flower,
they use special sensors that

can detect ultra-violet patterns
on the flower's petals.

We can see them, too,
with our special UV camera.

There are dark lines on the petals,

that mark the landing
strips for the bees -

guiding them to the nectar.

The spider, however, has developed
a way to exploit these signals.

Watching her with our UV camera,

we can see that she reflects
ultra-violet light.

So she appears even more conspicuous
sitting on a flower.

This extra brilliance acts
as a kind of super-signal

which the bee can't resist.

And the spider benefits.

In fact, the bees are more than
three times as likely

to visit flowers with UV-reflecting
spiders on them than those without.

The crab spider uses
a sophisticated range of colours

to deceive its prey.

But colour can also be
used in a simpler,

even more surprising way
to confuse the enemy.

And, on the plains of Kenya's Maasai
Mara, there's one animal

that uses just two colours
to outwit its predators.

The zebra.

Its black and white coat makes it
extremely obvious

as it grazes out on the open
grasslands.

Other grazers have softer,
gently varied colouration,

which blends with their background.

So, it seems strange that zebras,
apparently, do quite the opposite...

..particularly as they live
in a world

where there are so many hunters.

Lions...

..hyenas...

..and cheetah.

The boldly striped zebra seem to
be asking for trouble.

How do they get away with it?

The question has been hotly debated
by naturalists for centuries.

New research is now
suggesting an answer.

To understand how it might work,

we need to consider
the particular colours involved.

Black and white are two
of the most contrasting colours.

And no two animals
have exactly the same pattern,

so, each has a unique,
whole-body fingerprint.

But, when the zebras move,
the stripes create confusion.

It's known as motion dazzle.

And it makes it difficult
for a predator to keep focused

on one particular target.

The cheetah are looking for a meal.

To make a successful strike,

they must judge the distance
accurately and time it perfectly.

So, if a zebra's stripes
can confuse the cheetah

just for a few crucial seconds,
it may escape.

But there's another
threat on these plains.

BUZZING

Flies!

They are a real pest here.

They're not just a nuisance.

They carry diseases, some of which
are particularly nasty,

even deadly.

Despite the huge numbers of flies,

the zebras appear remarkably
untroubled by them.

There are plenty of flies around.

But few actually land on the zebra.

One theory is that
the black and white stripes

make it difficult
for flies to judge the distance.

To test this idea,

scientists counted how many flies
landed on animals

with gently graded colours and how
many landed on the zebra's stripes.

They found that four times fewer
flies landed on zebras

than on their more plainly
coloured neighbours.

Why should that be?

It seems it's another
consequence of those stripes.

They confuse the flies as they make
their final approach to settle.

Perhaps this creates a visual
blurring for the flies,

much as it does for a cheetah.

So, it seems that the zebra's
patterns of stripes creates

an optical effect that helps
protect them from enemies,

both large and small.

While zebras use different patterns
to confuse their enemies,

on the island of Cuba,
there are smaller

and rather slower-moving creatures

that do a similar thing.

This is Polymita picta,
a Cuban painted snail.

You might think that this one is
an exceptionally lovely,

eye-catching individual.

But it is not by any means
the only snail that is

so beautifully decorated.

No two individuals
are exactly the same,

yet all these belong
to the same species.

There are also five other
species of Polymita here.

Each snail has its own unique
combination of colours and stripes.

Their colours come from their diet -

lichen and mosses rich in minerals

that give the shells
these stunning colours.

They differ according to
the particular mix of plants

that each snail has been eating.

Variations of individuals
within a species is not

uncommon in the natural world.

It's called polymorphism.

But it's particularly
marked among Cuban snails.

Some scientists believe that
the variation in itself may be

a kind of defence against predators.

But how could that work?

Most animals looking for prey
have a search image in their minds.

They scan their surroundings
looking a victim

that matches their expectations.

If they see something
they recognise, they'll go for it.

And that's where the snail's
varying colours may come in.

The great range of different tints
and patterns, it seems,

confuses the birds.

He's never seen one
quite like this before.

And, while the bird is wondering
whether it is edible or not,

the snail can, slowly,
make a getaway!

So, it seems that colour
can both conceal and confuse.

And sometimes it's used in yet
a third, quite different, way.

Some poisonous animals,
like this little ladybird,

use colour as a warning.

It's bright red, and that's
a message which says

"Keep away, I'm poisonous."

Red, black and yellow are widely
understood as warnings.

So, the ladybird's message
is a truthful one.

It is poisonous.

But some animals,
that are in fact harmless,

have found it profitable to develop
these warning colours themselves.

This African queen butterfly,
like the ladybird,

is indeed very poisonous.

But this is a different species
entirely - a danaid butterfly.

It has almost exactly
the same colouration,

yet it's perfectly edible.

It is, you might say, using its
colours and patterns to tell a lie.

To our eyes,
and to that of the predators,

poisonous and non-poisonous
individuals look almost identical.

And that's the point.

The danaid mimics the colours
and patterns of the African queen

and, so, it isn't eaten.

Mimicry like this occurs
quite frequently among insects.

The yellow and black stripes
of this harmless hoverfly resemble

the warning colours of bees
and wasps that sting,

so, it's left alone.

Other animals use mimicry to hide.

This moth resembles a broken twig.

A kind of mantis closely matches
the shape and colours of a leaf.

Another mantis is shaped
and coloured like a flower...

..and gets a reward
for the resemblance.

And one particular caterpillar has
come to look like a tiny snake...

..while this butterfly's wings
take on the appearance

of dead leaves.

which use mimicry for a rather
more sinister purpose.

And one such creature lives here
on Australia's Great Barrier Reef.

Just beneath the surface,
the reef is a riot of colour.

But that means that there are great
opportunities for deceptions.

A bluestriped blenny.

It lives close to
a cleaning station -

a place on the reef where large fish
come to get their parasites

picked off by smaller fish
that feed on what they remove.

This little wrasse
is one of these cleaners.

It has a long-standing relationship
that relies on trust.

The big fish get a health treatment
and the little fish get a meal.

But the blenny has learnt how to
exploit this trusting relationship.

It leaves its hole
and starts looking for a meal.

But the big fish
don't seem to trust it.

It's time for a change of costume.

Filmed close up,
under controlled conditions,

we can see how the blenny's brown
stripes turn black.

The pigment cells in its skin

expand and contract to bring about
this subtle change.

But it's enough to do the trick.

The blenny now looks very similar
to a juvenile cleaner wrasse.

It's a devious disguise
and one that will help it

take advantage of the arrangement
the cleaner wrasse

has developed with its clients.

It's spotted a target,
a butterflyfish.

The blenny hangs back,

allowing an established cleaner
wrasse to start work.

Now the blenny slowly moves in,

as if to offer the same service
as the wrasse.

But once within range...

..it strikes!

Its razor-sharp teeth have removed
not just dead skin

but a chunk of flesh.

This isn't the treatment
the butterflyfish was expecting.

The blenny's deceit
may work for a time,

but, eventually,
it has consequences.

Reef fish begin to associate
the distinctive colours

of a cleaner wrasse with
the pain of the bites of a blenny.

Then they will eventually stop
coming to this cleaning station.

And that is bad for business
for the blenny, too.

So, it's time to let things
cool off.

A quick change back to brown
and its deception is over...

..for now.

All the while, it keeps its eye
on the cleaning station

and waits for its next target.

BIRDS CHIRP

Some animals change colour

for short periods of time
in order to deceive others,

but some use colour mimicry
permanently as a method

of persuading a different species
to rear their young.

One such creature lives here on
the grasslands of southern Zambia.

A nest, hidden in the grass.

It belongs to a pair
of common waxbills.

They are busy feeding their chicks.

The hungry youngsters open their
beaks to display a conspicuously

patterned gape which says,
in effect, "Food here, please."

And the parent obeys.

CHICKS CHEEP

But among them,
in this nest, there is an impostor.

One is significantly
bigger than the rest.

It hatched from an egg

that was surreptitiously laid

in the waxbills' nest

by a pin-tailed whydah.

Having done so, she flew away
leaving her young to be

cared for by the waxbills.

But why do the waxbills feed
this impostor?

The parent birds
recognise their young

by the pattern of their gapes...

..and the black-and-white markings
are characteristic of their species.

But the imposter's markings closely
mimic those of its nest-mates,

and because it is bigger,
it takes nearly all the food,

and the young waxbills
get little or none.

Two weeks later...

..and the young whydah
is much bigger.

CHICKS CHEEP

By now, however,

the adult waxbills have accepted

the young whydah as their own,

and the more it begs,

the more they give it.

One last meal from its luckless
foster parents...

..and the young whydah

leaves its nest-mates behind.

And this is what it will
grow up to be,

quite different
from the hard-working waxbills

that raised it.

All pin-tailed
whydahs are reared like this.

Mimicry wins.

Deceiving a different
species is one thing,

but in South Africa, one animal uses
mimicry to fool its own kind.

The Orange River,
the largest in South Africa,

and on it, the Augrabies Falls.

These are the main home

of a particular species
of flat-back lizards.

The males are brilliantly coloured.

The females, on the other hand,
are very different.

They are plain and drab.

The brilliance of a male's colours
is an indication

of its physical fitness
and strength.

The higher their status,
the more colourful they are...

..and they're not afraid to
make their seniority quite clear.

A side-shuffle dance,

showing off their colours,

is usually quite enough

to settle who is the boss.

But if that doesn't work,
they fight.

Their disputes are all
about location.

Sometimes they want a vantage
point from which to show off.

At others, a good place to hide,

or to get close to the river,

where there's food.

Here on these falls,
food means flies.

The river is a breeding
ground for blackflies.

There are huge swarms of them.

And they are the favourite
food of the lizards.

They have acrobatic skills
needed to catch them.

While the colourful males
are busy feeding,

a different kind of male appears.

He is brown, rather like a female.

There's just a hint of blue
on his throat

that gives him away as a male.

He's fully mature,

but not yet strong enough to compete
with his flashier neighbours.

To avoid fighting, he delays
the development of his colours,

and so mimics a female.

One in ten young males
behave in this way.

But he still needs to eat,

and to do that he's got to get down
to the river where the flies are.

That means getting past the
powerful, highly coloured males.

One thing could reveal
the deception.

He may look like a female,

but he smells like a male.

As long as he keeps his distance,
he'll be all right.

The big male hasn't noticed
that he's not a female.

Almost there.

Only one male now stands
in his way...

..the most dominant and aggressive
of the lot.

He's made it.

His disguise worked
and now he can feast on the flies.

He won't be able to keep
this up for ever.

Ultimately, all males have to
put on their glad rags

and develop those bright colours
if they are to breed.

For now, though, he's developed
a disguise that enables him

to cheat in one of nature's most
colour-dependant mating systems.

So, animals of all kinds

use colour in a multitude of
different ways.

New discoveries are giving us
fresh insights

into the lives of these animals...

..and new cameras
are allowing us to see

into a world of colour
as never before.

We're only just beginning to
understand the many different ways

in which animals use colour,

particularly those colours
that we can't even see.

For us, colour in the natural world

is a source of beauty and wonder,

but for animals,
it's a tool for survival.

We've seen in this series
that colour is crucial for survival.

So what happens to animals
when their world changes colour?

The experts we've worked with
in the field

have been helping us to find out.

In the Cairngorms, in Scotland,
I met Jim Cornfoot, a land manager

and an expert on the natural
history of these mountains.

How long have you been here now?

Over 30 years
since I started up here,

so I've seen a lot of different
changes, you know.

In what way?

On the Cairngorm Plateau, there's
areas where we have snow patches

lasting all the year round,

but if you look at the last
sort of 20 years,

there's five, six times where
the snow's completely gone,

and in over sort of 200, 250 years,
there's only been seven times

that that's happened.

Has that had a great effect
on the wildlife?

You know, they're out of kilter,
basically,

with what's going on around them.

So things like mountain hare,
ptarmigan,

they're standing out with the browns
and the heather behind them.

And they're still white?

And they're still white, yes,
so they're not set up for that,

so if it's a very poor winter,

you know, they're suffering.

Ptarmigan, a kind of grouse,

live year-round
in this exposed environment

where there are few places to hide.

But now, as the world warms,
things are changing dangerously.

The recent decrease in snow cover
has made them only too conspicuous.

Animals like this mountain hare,

also in its winter coat,
can be seen from far away...

..and that makes life
very hazardous.

BIRDS SQUAWK

These changes are affecting animals
all around the northern hemisphere.

In North America, the reduced snow
cover has caused snowshoe hares

to be mismatched on average
for a week a year.

During the time, the hare is 10%
more likely

to end up as someone else's dinner.

By the end of the century, the loss
of snow cover is predicted to expose

the hares
for up to eight weeks a year,

so increasing their annual
mortality by almost a quarter.

Unless they can adapt rapidly,

they could be in serious
danger of extinction.

While a warming climate is causing
problems in northern habitats...

..it's also driving colour changes
in other parts of the world...

..including some
of the most beautiful,

colour-rich habitats
on our planet...

..coral reefs.

Our Australian team spent months
filming on the Great Barrier Reef.

In these sunlit waters,
colour is everywhere.

But this habitat is being subjected

to the most drastic colour
change imaginable,

and our crew witnessed it
first-hand.

The corals have suddenly
turned into white skeletons.

It's called coral bleaching

and it's now happening
only too frequently.

On the Great Barrier Reef,

such events have increased
from once in every 25 years

to three events in the last five.

Professor Jorg Wiedenmann
from the Coral Reef Laboratory

at the University of Southampton

has been working to discover
what is behind these changes.

The key is the relationship
between coral

and the microscopic algae
that live in their tissues.

These algal partners
are called symbionts.

It's they that give
the coral its colour.

The algae, when they photosynthesise
during the daylight hours,

use sunlight to grow,
excreting sugars as a by-product,

which are then
absorbed by the corals.

This partnership was established
during the time of the dinosaurs

and has been such a success
that it has created structures

that are visible from space.

But warming seas are disrupting
this system.

So, when the seawater temperatures
rise above a critical threshold,

the photosynthetic machinery
of the algal symbionts

starts to malfunction.

They begin to produce toxic
compounds which cause

the corals to expel them
from their tissues.

So the coral loses its colour.

It bleaches.

Sometimes the bleached corals die,
and then the entire ecosystem,

together with everything it
supports, is lost.

Almost half of the corals
in the Great Barrier Reef

have died this way
over the last 15 years.

But in the last decade,

there have been reports
from various parts of the world

of coral developing
startling neon colours.

We're just beginning to realise

that corals are using colour
to fight back.

Jorg is studying how this works.

This coral has lost
its algal symbionts,

but instead of turning white,

it's producing these bright,
neon-green pigments.

The coral produces these pigments
to protect the remaining algae

inside of the tissue
from excess light stress.

So they act as a sort of sunscreen
for the symbiont algae.

This coral sunscreen makes it more
likely that the bleached coral

will be able to take
back its algal partners,

restoring its food supply, its
colour, and helping it to recover.

But even this extraordinary
adaptation is not enough

to protect coral against
all the changes it is now facing.

If corals have been exposed
only to mild stress,

then they can
recover from bleaching.

But if corals are subjected
to prolonged

or extreme levels of heat stress,

they lose their ability to create
these sunscreen pigments

and are likely to die.

And unfortunately, global warming
is making this more likely.

There's a severe danger

that corals will be exposed to
episodes of stress

where they can't recover and where
they can't use these pigments

to bounce back from bleaching.

So, although colour
might be helping coral reefs

to tolerate some of the change,

only action to halt global warming
will ensure their survival.

If warming continues, then they,

together with the beautiful array
of colour they provide,

will disappear from the reefs
of the world.