(HE MAKES BIRD-LIKE CALL)
(BIRD RESPONDS)
This bird is communicating directly with me.
What's more, its call is one it only uses when signalling to humans.
And its message is quite explicit and precise.
It's saying, "Follow me," so let's do just that and see what happens.
The bird, here in Kenya, is a honeyguide,
and my companion has summoned it with a special call.
Man and bird have a mutual understanding,
which began in prehistory and still today enables them to speak to one another.
The bird flies ahead, alights on a conspicuous perch,
and then waits for us to catch up.
We don't know how far it will take us...maybe a mile or so.
The bird has stopped its chatter and for the first time is perching low.
A buzzing is coming from rocks close by.
There are certainly bees coming out,
so with any luck there's some honey, and if we can get it out,
then we can complete our share of the bargain with that bird.
African bees have very effective stings,
so it's sensible to stupefy them with smoke
before you attempt to steal their honey.
The bird sits quietly by,
waiting for us to do the part of the job it can't manage.
Mmm!
It's delicious!
If the bird hadn't shown us where this nest was,
I'd have never got this sweet reward.
But if we hadn't broken open the nest, the bird would never have got any honey.
So this is the result of a message sent by a bird to a man.
Since it is a partnership, it's only fair that the bird gets a reward.
So it's the custom here not to take all the honey,
but to leave some of it for the bird.
So two different species solve the trial of talking to strangers.
You have to get your message through, not only to friends but to enemies.
As the wild dogs start hunting, the gazelles don't simply run away.
They make these extraordinary leaps...they stot.
In this action is a message which says, in effect,
"My jumps show I'm strong and could probably outrun you.
"Someone else would be an easier catch."
As the dogs rush across the plain, they choose which gazelle to go for
on the basis of this information.
These messages are truthful,
for the frequency of a gazelle's leaps do indicate its strength.
And the dogs hardly ever select those that stot with vigour.
Interestingly, the gazelles rarely stot when pursued by a cheetah,
for the cheetah selects its prey before the chase
and catches it with a sprint.
There's no time for messages.
But with dogs, it's different.
Dogs are not sprinters, they're long-distance runners,
and they catch their victims by tiring them out.
A gazelle's message is inevitably honest.
A weak individual can't counterfeit strength.
But animals don't always tell the truth.
This bird, for example, tells downright lies.
It's a ringed plover, and it nests on the shingle of European beaches.
Its eggs are perfectly camouflaged.
The bird itself, when sitting on them, is much more obvious.
So when danger threatens, the logical course is clear.
A possible predator like me is unlikely to find the eggs
and more likely to follow the bird, that has a way of persuading me to do so.
(CONSTANT CHIRPING)
It's saying, in effect, "I'm injured with a broken wing.
"If you're looking for an easy meal, why not pick me up?"
But, of course, it's not true.
It's just a device to lure me away from its eggs.
Suddenly, its broken wing gets better.
Since I'm so far away from its nest that I'm unlikely to find the eggs,
back it goes.
Whether an animal is honest or dishonest,
the way it sends its messages has to suit the sort of place it lives in.
Here in Israel, for example,
there's an animal that spends its entire life underground.
Molehills like these are normally the only sign of its presence.
It's totally blind, it can hardly smell, and has poor hearing,
and yet individuals 40 or 50 yards apart
can communicate with one another through the solid earth.
This is a geophone.
Basically it's just a device which turns ground vibrations into sound
which I can hear and record on this.
With it, maybe I can have an underground conversation!
That's my message.
(THUMPING)
And there's a reply!
The animal's not hearing sound, it's just responding to vibrations.
I'm talking to a mole rat.
This hairy mole rat, different from the naked mole rat of Africa,
sends messages by beating the roof of the tunnel with its head.
It receives them by pressing its jaw to the wall to feel the vibration.
They burrow continuously, and their tunnels extend for hundreds of yards,
winding circuitously and often crossing those of others,
as they search for roots and tubers.
But outside the breeding season they're very anti-social,
and they do all they can to avoid meeting a rival coming the other way.
So they constantly send signals saying where they are
and listen out for messages from others.
They exchange challenges, "Who will give way?"
If they're so confident of themselves that they ignore these warnings,
and the two tunnels actually meet, then there is always a fight.
Unless one surrenders its tunnel,
this can only end in the death of one of them.
Messages sent as vibrations in soil don't go far.
Vibrations in air travel much greater distances.
They are sounds.
The palm cockatoo beats out his claims to a nest hole
using a branch as a drumstick.
(SQUAWKING)
Sound travels best when the air is cool and still, at dawn.
And the songs that penetrate furthest through the foliage
are simple and very loud.
(LOUD WHOOPING CALLS)
This is Madagascar.
(LOUD WHOOPING CALL)
The indri, the largest of lemurs.
They live in families - a male, a female with her baby.
And, often, a half-grown youngster.
The female is the lead singer.
The group's message proclaims its ownership of the territory
and of the food it contains.
Neighbours defiantly respond with their own claims,
so soon the forest is ringing with the calls of many groups.
(INCREASING DIN OF CALLS)
The chorus is a marvellous one, but each call in structure is simple.
But some primates have very complex calls.
The most elaborate so far analysed
can be heard on the shores of Lake Naivasha in Kenya's Rift Valley.
At dawn, vervet monkeys come down from the trees
to search for food on the ground.
Down here, of course, they're much more vulnerable than in the trees,
but there's always a sentinel on watch.
The sentinel gives a call which means, "Snake!"
(CLICKING NOISE)
The meaning is very precise and only made when a snake appears.
It could be called a word, and when other vervets hear it
they know exactly what the danger is.
Calls with such specific meanings are very rare in the animal world.
The vervets have developed several of them.
Apart from man, no other wild animal
has been shown to use so many different word-like alarm calls.
A call that means, "Danger from the air!"
The vervets run into the denser branches where the eagle won't go
for fear of damaging its wings.
From the safety of the branches, the vervets scream furiously.
And one is even brave enough to launch a lightning attack.
Monkeys are not the only ones to fear the eagle - so do small birds,
such as the superb starling.
Vervets understand the starling's vocabulary.
The bird shrieks a warning, "Danger on the ground!"
The monkeys repeat it using their own term, and everyone runs for it.
So sounds can carry a great deal of information.
But with the coming of darkness,
another way of sending messages becomes possible.
Sound is not the only way of communicating at night.
When the sun goes down on the tidal rivers of Malaysia,
the trees become alive with animals communicating...
...with light.
At first, there are just a few twinkles in the branches.
But about three-quarters of an hour after sunset, the show begins.
These are fireflies, thousands of tiny beetles about 5mm long,
each sending a message in Morse code with a lantern in its tail.
All those that are flashing are males,
and their message is directed to the females, and it's a simple one:
"Come hither, mate with me."
This particular species, as well as one or two others in south-east Asia,
reinforce that message and send it the farthest possible distance
by all flashing in perfect time together, in perfect synchrony.
The result is that, even after I've drifted many yards downriver,
I can still see their tree outlined with pulsing light.
This display continues throughout the hours of darkness every night of the year
and extends for miles along the river.
The combined light of all these tiny beetles is so bright
that fishermen at sea can use them as navigating beacons
to guide them back to their home rivers.
Only in south-east Asia do fireflies coordinate flashings in this spectacular way.
Elsewhere in the world, they operate independently,
each beaming its own individual invitation to mate.
Walk in the woodlands of the eastern United States at dusk in summer,
and you can find fireflies all around you.
What's more, with these you can actually communicate,
if you have a small torch like this.
To communicate with the males flying a foot above the ground,
I have to accurately imitate the call of a female.
In the species that's flashing now,
the female observes the male's flash, then waits two seconds
and produces a half-second flash of her own like this.
Let's see if I can do it.
There's one!
Flash, two...from me.
One, two, flash. It's coming.
Flash from him, one, two, flash from me.
Here he comes, here he comes!
There we are, he's settled on my finger.
Got him!
There he is.
Well, I'm afraid I'm a disappointment to you.
If you want to find the greatest number and variety of animals
that communicate with light,
you have to go to the darkest place on Earth,
somewhere far beyond the reach of the sun's rays,
where human beings hardly ever go - to the depths of the ocean.
This is the Johnson Sealink.
At the front is an array of remote-controlled TV cameras and searchlights.
I'm sitting beside the pilot in the bubble in the middle,
and the whole craft is massively strengthened
to withstand the huge pressures of the depths.
As we go down, it gets darker and darker.
The water is thick with small floating organisms.
At 600 feet, the water outside is twenty times atmospheric pressure.
The temperature is within a few degrees of freezing,
and we are far beyond the reach of sunshine.
You'd think in such a hostile environment
there would be very few animals living, but watch this.
The chorus of light is being made by hundreds of small deep-sea creatures
which are flashing in response to my light.
Now, if I turn on the lights of the submersible,
we may glimpse one of these strange deep-sea creatures as it drifts by.
The pilot has remote controls for the camera outside the sub
to search for them in the blackness.
This is a comb jelly as big as a football.
It's been nicknamed 'Big Red', but it has yet to be given a proper name.
It's new to science.
Another new, undescribed comb jelly.
Though specimens have been brought up,
it's only been seen alive through the windows of deep-sea craft like this.
It uses a pair of long retractable tentacles to catch fish.
A jellyfish, Solmissus, two feet across,
which, in spite of pressure changes,
sometimes swims quite close to the surface.
Kiyohimea, another comb jelly,
one that is surrounded by gauzy skirts.
But for the most sensational spectacle,
you have to turn the lights of the submarine off.
A jellyfish outlined by its own pulsing illuminations.
A squid, its lights moving as its body throbs.
Displays like this may serve for defence or to send messages.
No one knows.
And most spectacular of all,
another jellyfish with its own amazing rhythmic flashing system.
These creatures are among the most loquacious animals in the sea.
They send and receive such complex messages,
they could be considered to be having a conversation.
And they do it entirely visually. They are squid.
The variety of their colour changes are so great
that it's hardly possible for us to keep up with their exchanges.
They produce these colours and patterns with tiny sacs of pigment,
which can expand from an almost invisible speck
to a large blotch and back again in a fraction of a second.
They're all controlled by a complex nervous system.
It's not only colour changes they use in their visual conversations;
the position of the body also has significance.
Researchers have so far discovered 35 different postures,
which act as adverbs,
qualifying the intensity of the message sent by the colour change.
This male reef squid appears to be saying nothing, seen from this side.
Its flank is a blank.
But his other side is vivid with colour changes.
He's chatting up the female beside him.
Rival males passing by would never know what he's up to.
The male at the back has developed a striped pattern.
That's an invitiation to mate.
The female goes white, that's a refusal.
When another male tries to edge in, they exchange a series of swift messages.
That is the beginning of an argument.
The reef squids' system of communication is certainly complex,
and we don't fully understand it.
But there are other animals in these Bahamas waters
that have a system that is even more complicated still.
They're mammals like ourselves,
they seem positively to enjoy our company,
and most ships have them riding on their bow waves
apparently just for the fun of it.
They're dolphins.
This crystal-clear patch of the ocean
is the home of sixty or so spotted dolphins.
Though our ears are not adapted to hearing underwater,
I could catch something of their near continuous conversations.
They're full of curiosity, playing with odd things they find like twigs,
and swimming among them leaves you in no doubt of their intelligence.
(CLICKING)
Like narwhals and other whales, they use ultrasonic clicks.
They've a huge range of whistles.
Over thirty sounds have been identified,
each with a different meaning.
Every dolphin has its own particular name whistle.
One attracts the attention of another by whistling this call sign
just as we shout to someone using his name.
Baby dolphins have name whistles derived from their mother's -
inherited, in fact, rather like human surnames.
This baby is accompanied by a young female looking after it,
but now its mother returns and the baby whistles to her excitedly.
When they are close by, they may rub fins,
just as we might shake hands.
Most remarkable of all,
they combine both sound and visual signals in their communications.
They will often take up a particular position,
hanging vertically in the water or lying still on the bottom.
Each posture gives each sound a different meaning,
so enormously increasing their vocabulary.
They enjoy mimicking, as though agreeing with one another.
They will even mimic you, as you spin or hang in the water.
So these animals can communicate in four different ways:
with sounds which we can hear;
with ultrasounds which we can't;
with body postures which change the meaning of any sound;
and with touch.
The result is an amazingly complex web of communication,
unexcelled by any other animal except ourselves.
But how marvellous it would be if we could become a part of that.
An Indian florican. He's got a problem.
He wants to attract females,
but in tall grass it's not easy to tell them where he is.
He's so anxious to impress females with his fitness as a mate
that he may do this 400 times a day!
On the open grasslands of central Asia, the steppes,
lives an animal that invites prospective partners with a perfume.
The dwarf Siberian hamster.
This female is about to give birth,
but first there is something else she must do.
She marks the vegetation around her burrow with a secretion.
As the day begins to dawn, she retires below ground to her nest
and there gives birth.
Her half-dozen babies are underdeveloped, naked and blind,
for they've only spent 28 days in her womb.
She's unlikely to live longer than a year, and she has no time to waste.
Now she must supply her babies with some milk.
But because this may be her only breeding season,
she's also in a great hurry to mate again.
Her hormones don't allow her to do both at the same time,
and she has just three hours between delivering her babies
and supplying them with milk.
So the effectiveness of that perfume she posted up last night is crucial.
The wind has spread it over the steppes,
and males within half a mile in any direction will have detected it.
Here they come, full of excitement.
So once again she couples.
But hamster mating is quite a long business.
One copulation is not enough.
The male follows her to her burrow to make sure no rivals from outside
manage to displace him.
An hour or so later, he's still with her.
While this has been going on,
other hamsters have been wandering around,
seemingly unaffected by all this excitement.
Why should this male, within three feet of the perfume, ignore it,
when that same message will bring another male from half a mile away?
The fact is this male,
although he looks like the female, is a different species.
He feeds mainly on insects, she on seeds and grass.
Her message contained two statements:
not only, "Hurry, I want to mate," but also, "This is who I am."
And this male knew that she was not for him.
That second part of the message is very important,
because it prevents animals from trying unsuccessful matings.
Boobies are ocean-going birds common throughout the tropics,
and there are six species of them.
As several kinds may nest on the same island, there could be confusion.
But this is a blue-footed booby,
and when a male starts to court a female,
he leaves her in no doubt about that.
Bluefoots don't make a proper nest, just a scrape,
but this nest-making urge remains in their courtship.
How better to indicate your willingness to mate than with some token nest material,
deposited on your partner's attractive blue feet?
Male ducks, like this wood duck, grow new feathers each spring.
During the winter they, like their females, were plain brown.
A male merganser. His female is also brown.
The female ducks incubate the eggs by themselves,
and a sitting duck needs camouflage.
The males reinforce their costumes with displays.
He bobs his head and his female responds invitingly
by vibrating her tail and swimming low in the water.
The golden-eye favours a more restrained head-bob,
but that is all his female needs to be convinced he is the right partner.
But how does a duck know what its mate should look like?
Females know innately, but the males have to learn.
The first moving thing ducklings see
as they emerge from the shell is their mother.
This image becomes imprinted in their brains,
and for the next few weeks they will follow it unwaveringly.
The male duckling never forgets his mother's appearance,
and when a mallard starts looking for a mate,
it's her that he seeks to match.
But this male duckling is not a mallard, he's a young golden-eye.
He hatched from an abandoned egg given to a mallard foster mother.
Though he looks different from the mallards,
he's accepted into her family and follows wherever she goes.
Next year, if he survives,
he'll be in the same predicament as this adult golden-eye.
He, too, was brought up by a mallard foster mother.
The female golden-eye, impressed by his plumage, makes the right signals.
Another joins her.
He ignores them both.
His displays are for a female like his foster mother, a female mallard,
and she, alas, finds his signals totally incomprehensible.
But being the right species is not necessarily enough.
An individual male may have to have some extra attraction to offer.
This tree stump, here in the forests of Central America, contains water,
just what a female damselfly needs, as she can only lay eggs in water.
So any male that can claim this and drive off rivals
really has something to offer.
The distinctive flight with which he proclaims his ownership of a pool
has given it the name of helicopter damselfly.
Rival males are chased away.
But a female will be attracted by his display and lay eggs in his pond.
He remains on guard after she's gone and welcomes other females,
so that eventually his precious pond, if it's large enough,
may contain several larvae.
But he is father of them all.
Other male insects offer other enticements to their females.
Hanging flies in North America.
They are hunters.
Flies are their favourite food, if they can get them.
But beetles may have to do.
This male has caught a fly but doesn't eat it all.
He uses it as a bait for a female.
To advertise it, he fans his wings and disperses a perfume
from the tip of his abdomen.
A female approaches.
Had this been a small fly, she wouldn't have stayed,
but she approves of this large one, and, as she feasts on it,
she allows the male to mate.
He won't let go of his gift.
Transferring sperm for a hanging fly is a lengthy business,
and it may take him 20 minutes to complete it.
He grips her securely while she continues to feed.
Mating completed, he releases her.
She wants to take the fly with her, but he wants to keep it.
A wrestling match starts.
He wins.
Even a second-hand meal may attract another female.
And within a minute or so, another female is interested.
The male epauletted bat attracts his females
by bristling the white patches on his shoulders.
The females hang around nearby, assessing these invitations.
Their relationship will be no more than a visit of a few seconds
during which they mate.
The males offer no extra inducements,
such as rich territories, nest-making skills or bribes of food,
only their qualities as a father for the female's baby.
The female must select the healthiest and most attractive male
so that her baby can inherit such qualities.
Choosing which he is to be demands a close inspection of the candidates.
The male supports the entreaties proclaimed by his bristling epaulettes
with energetic honks,
but serenades can be more beguiling than his.
(RHYTHMIC, VARIATED CALLING)
The lyre bird of Australia produces
one of the most varied and glorious of all animal songs.
Each male maintains several courts in his territory
on which he sings and dances.
He tours from one to the other and cleans them meticulously
before he starts his performance.
(CONSTANT SINGING)
He's a superb mimic.
An experienced male can mimic nearly all the other birds in his territory.
(TOTALLY DIFFERENT NOTES)
That's a very accurate imitation of the laugh of the kookaburra.
The males, like the male epauletted bats, take on no parental duties.
They leave nest-building, incubation and feeding the young to the female,
so they're able to devote all their time and energy to these displays.
Females travel from one territory to another assessing the males
for the complexity of their song and splendour of their plumes.
A particularly successful male may mate with many females.
The lyre bird is unusual in having both a song and magnificent plumes.
Most birds invest in one or the other.
Those that rely on visual displays
have developed the most ravishing costumes.
The Palawan peacock pheasant from the Philippines.
The standard-winged Bird of Paradise from the Molucca Islands,
with some of the oddest of all plumes.
The rifle bird of Australia.
This appetite of females for increasingly dramatic spectacles
has forced the males to dance to their tune in ever more extreme ways.
Surely the most spectacular of all is the display of the peacock.
Elaborate plumes are something of a handicap.
They make it more difficult to fly
and also make it more conspicuous for predators.
So it's not surprising most birds after the breeding season shed them.
But that's a considerable waste.
One family of birds, the bowerbirds, have found an ingenious way
of avoiding these two disadvantages.
This is not a nest.
It's a display case built by the male bowerbird
to show off the objects he collects to impress the female.
He gathers together flowers, feathers from other birds,
anything brightly-coloured.
The satin bowerbird that built this bower prefers blue objects.
He's fussy not only about their colour but their arrangement.
So if I take this blue parrot feather and put it there,
he won't like it at all.