[sweeping orchestral music playing]
[Attenborough] 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.
[suspenseful orchestral music playing]
The Indian subcontinent is home to some truly spectacular animals.
[bird calling]
Most, like these peafowl, use colour to attract attention,
and the colours 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's 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 the world…
and this is how the 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.
[suspenseful orchestral music continues]
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're 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.
[calling]
[monkeys calling]
[calling]
[monkeys calling]
The langur sounded the alarm before she could get close enough.
[panting]
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.
[growls softly]
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.
[snarls]
[suspenseful orchestral music playing]
The deer seem to sense danger.
They still can't see her.
[suspenseful orchestral music intensifies]
[sambar bleats]
[sambar calling]
[water splashing]
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.
[wind whistling]
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.
[ptarmigan croaking]
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.
[tense orchestral music playing]
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.
[wind whistling]
But many plants, of course,
do the reverse.
[whimsical orchestral music playing]
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's waiting for her prey.
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 ultraviolet 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 ultraviolet 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 Masai Mara, there's one animal
that uses just two colours
to outwit its predators.
[laid-back orchestral music playing]
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.
[menacing orchestral music playing]
Lions,
hyenas,
and cheetah.
[snarling]
[growling]
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.
[zebras snorting]
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.
[tense orchestral music playing]
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, looking for a meal.
[zebra snorts]
[suspenseful orchestral music playing]
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.
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.
[laid-back orchestral music playing]
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 zebras' 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 zebras' 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.
[tranquil orchestral music playing]
You might think that this one is an exceptionally lovely,
eye-catching individual.
But it's 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?
[menacing orchestral music playing]
Most animals looking for prey
have a search image in their minds.
They scan their surroundings looking for a victim
that matches their expectations.
If they see something they recognise, they'll go for it.
And that's where the snails' 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's 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.
[serene orchestral music playing]
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.
But there are some animals which use mimicry
for a rather more sinister purpose.
And one such creature lives here on Australia's Great Barrier Reef.
[enchanting orchestral music playing]
Just beneath the surface,
the reef is a riot of colour.
But that means
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 learned 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.
[unsettling orchestral music playing]
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.
[unsettling orchestral music intensifies]
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.
[birdsong]
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.
[whimsical orchestral music playing]
A nest, hidden in the grass.
It belongs to a pair of common waxbills.
They are busy feeding their chicks.
[chicks chirping]
The hungry youngsters open their beaks
to display a conspicuously patterned gape,
which says, in effect, "Food here, please."
And the parent obeys.
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.
[chicks chirping]
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 impostor's markings
closely mimic those of its nest-mates.
And because it's 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.
[tranquil orchestral music playing]
[chicks chirping]
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 hardworking 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.
[whimsical orchestral music playing]
These are the main home of a particular species
of flat-backed 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.
[flies buzzing]
And they are the favorite 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.
[mysterious orchestral music playing]
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.
[jaunty orchestral music playing]
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.
[tense orchestral music playing]
[jaunty orchestral music playing]
He's made it.
His disguise worked,
and now he can feast on the flies.
He won't be able to keep this up forever.
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-dependent 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.
[sweeping orchestral music playing]
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.
The story of Life in Colour continues.
We delve even deeper into the lives of these animals
and discover how science cracks the code of colour
to see into a world that is invisible to us…
[man] Look at that. That's extraordinary.
[Attenborough] …revealing the hidden secrets of Life in Colour.