The Trials of Life (1990) s01e11 Episode Script

An Indian florican.
He's got a problem.
He wants to attract females and mate, but in tall grass it's not easy to tell them where he is.
He's so anxious to impress females with his strength and fitness as a mate that he may do this 400 times a day.
There are, of course, other ways of broadcasting such messages in places where it's difficult to be seen.
A nightingale in an English woodland in spring.
He's recently arrived from his winter quarters in Africa.
(SINGS) He continues singing into the night, perhaps because the females who arrive after him usually travel under cover of darkness and may be passing overhead.
Whales sing, too.
The song of the female right whale travels great distances through the water and can be heard by other whales at least five miles away.
Her calls also announce that she's ready to mate, and the males who have gathered around her push and butt one another to get alongside her.
The act of coupling lasts only a few seconds, so the males have to be ready to seize the chance.
Teasingly, she rolls over, preventing the jostling males from mating with her just yet.
She is encouraging competition between her suitors.
Males who are bigger and stronger will push rivals out of the way to lie beside her and mate when she allows it.
That way she achieves the objective of her courtship - to secure the best father for her calf.
0n the open grasslands of central Asia, the steppes, lives an animal that issues invitations to prospective partners with a perfume.
The dwarf Siberian hamster.
This little female is about to give birth, but before she does there is something else she must do.
She marks the vegetation around her burrow with a secretion from beneath her tail.
As the day begins to dawn, she retires below ground to her nest chamber and there gives birth.
Her half-dozen babies are still very underdeveloped, naked and blind, for they've only spent 28 days in her womb.
But she's unlikely to live for much 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 things at the same time, and she has just three hours between delivering the last of her babies and supplying them with milk.
The effectiveness of that message of perfume that she posted up last night is now crucial.
The wind has spread it all 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.
0ne copulation is not enough.
The male follows her down into her burrow to make sure none of his rivals outside manages to displace him.
An hour or so later, he's still with her.
The other males have missed their chance.
While all this has been going on during the night, other hamsters have been wandering around, seemingly unaffected by all this excitement.
But why should this little male, within two or three feet of that female's perfumed message, ignore it when that same message will bring another male from half a mile away? The fact is that this male, although he looks very 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 a mate,'' but also, ''This is who I am.
'' And this little male knew that she was not for him.
And that second part of the message is very important.
It prevents animals from trying to achieve matings that can never be successful.
The more crowded the environment, the plainer these statements must be.
The coral reef has the densest and most varied population of fish of any part of the sea.
Butterfly and angel fish are among the commonest.
There are many closely related species, all with very similar-shaped bodies - roughly rectangular.
But the colour patterns on these rectangles are as varied as the designs on national flags.
With such clear declarations of identity emblazoned on their bodies, no one is likely to court an unsuitable partner.
When courtship begins, individuals must make sure that their identity badges are prominently displayed.
Boobies are ocean-going birds, common throughout the tropics.
There are half a dozen species of them.
Since several kinds may nest on the same island, there could be some 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.
(H0NKING CALLS) Bluefoots don't make a proper nest, just a scrape, but a relic of this nest-making urge remains in their courtship.
How better to indicate your willingness to mate than with a little token nest material deposited on your partner's attractive blue feet? The bluefoot's identity badge is permanent - its feet are blue throughout the year - but other birds only wear their badges during the breeding season.
Male ducks - this is a wood duck - grow new feathers each spring.
During the winter they, like their females, were a plain brown.
A male merganser.
His female is also drab.
The female ducks incubate the eggs by themselves, and a sitting duck needs camouflage.
The males reinforce their costumes with displays.
The smew bobs his head and his female responds invitingly by vibrating her tail and swimming low in the water.
The golden-eye favours a rather more restrained head-bob, but that is all his female needs to be convinced that he is the right partner for her.
But how does a duck know what its appropriate mate should look like? Females know innately, but the males have to learn.
The first moving thing ducklings normally see as they emerge from the shell is their mother.
This image becomes imprinted in the brain of the ducklings, and for the next few weeks they will follow it unwaveringly.
The male duckling never forgets the appearance of his mother, and when a little 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 completely accepted into her family and he follows her wherever she goes.
Next year, if he survives, he will 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 of acceptance.
Another joins her.
He ignores them both.
They're not what he's seeking.
His displays are directed to 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 a pool of water, and that's just what a female damselfly needs, because she can only lay her eggs in water.
So any male that can claim this and drive off rivals really has something to offer.
This is the biggest of all damselflies, and the distinctive flight with which the male 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 will readily welcome other females, so that eventually his precious pond, if it's large enough, may contain several larvae.
He is father of them all.
0ther 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 he 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 released from the tip of his abdomen.
A female approaches.
Had this been a small fly or a beetle, she wouldn't have stayed, but she approves of this large, juicy one and, as she feasts on it, she allows the male to mate.
But 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 remains of the fly with her, but he wants to keep it, and 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.
Aerobatic skills are what impress tropic birds.
Both male and female will have to catch food at sea for their nesting, and when adults select partners, both sexes assess each other's merits as a likely future parent.
At the beginning of the season, large groups display together.
Soon the birds pair off and then, for minutes on end, again and again, they perform the most elegant pas de deux.
A marsh harrier, seeking to impress his mate, provides absolute proof of his prowess as a hunter.
She takes his catch from him in mid-air.
He gives an exhibition of slow-speed flying, with legs lowered, over a likely nest site.
The female alone will construct the nest, but he will collect a great deal of the building material, and he demonstrates his ability to do so.
The pair also display by clasping as they fly not only building material and prey, but one another.
He will continue to feed her in this way throughout the nesting period.
Termites.
The favourite food of the red-backed salamander.
This male has a territory that contains lots of termites, and his droppings provide the evidence.
They are smooth and even compared with these, deposited by a salamander who's been feeding on ants.
Ants are not nice to eat.
They have indigestible horny coverings to their bodies and stings loaded with formic acid - not nice at all.
But if that's all there is in your territory, well, they're better than nothing.
A female looking for a mate.
She wants a male with a territory rich in termites, where her young can get a good start in life.
This place is clearly no good.
This, on the other hand, might be better.
She makes quite sure.
Having convinced herself of the quality of this male's territory, she traces him to his burrow.
Here she will mate and leave her eggs.
Moose, in the rutting season, also develop a fixation on excrement.
A bull moose establishes a territory in areas favoured by females.
0ther males have to be kept away.
The male has a special way of encouraging females to mate with him.
Every day, he urinates in special pits.
His urine has a smell that the females find both pleasurable and exciting.
That brings them into sexual receptivity.
They wallow in the pits, drenching themselves in his perfume.
All of the females in the group want a turn, but the one in occupation is frequently very possessive.
Perfume is also used by this bat to attract and keep a harem.
He is a sac-winged bat in Trinidad and he establishes a roost for his females on the side of a silk cotton tree.
When a female returns at dawn, he stretches out his wing to expose a perfumed gland on his elbow.
The females find this smell highly attractive.
He wafts his scent towards them .
.
and then hovers in front of the female so that his perfume surrounds her, a perfume that stimulates her and binds her to him socially.
These bright flashes and calls are made by another bat.
(CHIRPING CALL) A male epauletted bat.
The females of this species assess these invitations with care.
Their relationship with a male will be no more than a visit of a few seconds during which they mate, but which male is it to be? The males have no extra inducements on offer, such as rich territories, nest-making skills or even 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 has a good chance of inheriting 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, MUSICAL CALL) 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 in the bush on which he sings and dances.
He tours from one to the other and cleans them meticulously before he starts his performance.
(CHIRPING S0NG) He's a superb mimic.
An experienced male can sing the songs of nearly all the other birds in his territory.
(SQUAWKING) 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 entirely 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 rival 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 an elaborate song and magnificent plumes.
Most birds invest in one or the other.
Those that rely primarily on visual displays have developed the most ravishing costumes.
The tragapan from Western China.
He only reveals the full beauty of the wattles on his throat when a female approaches.
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.
It's this appetite of females for increasingly dramatic spectacles that has forced the males to dance to their tune in ever more extreme ways.
And surely the most spectacular of all is the display of the peacock.
Elaborate plumes are something of a handicap.
They make it more difficult for the bird to fly and they also make it more conspicuous for any predator to find.
So it's not surprising that most birds, at the end of the breeding season, shed them.
But that is a considerable waste.
0ne family of birds, the bowerbirds, have found a very ingenious way of avoiding these two disadvantages.
This is not a nest.
It's a display case built by the male bowerbird in order to show off the objects he collects to impress the female.
He gathers together flowers, feathers from other birds, anything as long as it's 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 just there, he won't like it at all.
The male alone is responsible for building these showcases.
Females regularly tour the bowers, assessing their riches.
The arrival of one stimulates the male to posture and strut.
But she's not yet made up her mind.
There may be a more impressive bower elsewhere.
A rival and more dominant male appears.
He steals the treasures while the proprietor of the bower is away.
He does more.
He's not only a thief but a vandal.
And he uses the remains of the demolished bower to reinforce his own.
He now has the most spectacular collection of decorations in the whole neighbourhood.
And this individual embellishes his treasury in yet another way.
He paints its walls with a blue paste made from mashed berries.
It's all done to impress the female.
If she is going to mate, it will be here between the walls of the bower that she will receive him.
There are 18 different species of bowerbird, each with its own architectural design for a bower and its own taste in ornaments.
This is the bower of the golden bowerbird.
Up here in the forests, which are rather wetter, there's a kind of fungus which grows on twigs binding them together.
So this bower is a much more solid structure and much less easily destroyed than that of the satin.
Indeed, this particular bower may be as much as 40 or 50 years old.
This is the perch on which the bird displays.
And here are its treasures, which are not blue, but pale green, with white flowers with black seeds in them.
And there's one further difference with the satin bird.
The golden bowerbird is a much shyer creature.
If I'm going to be lucky enough to see it, I'm going to have to retreat some distance.
He's got another of those white flowers.
A female having a critical look.
The male sneaks onto a neighbouring bower while the owner is away.
The tower of twigs may be a fixture, but the treasures can be filched.
The rivalry between black grouse is rather more obvious.
The males, here displaying in Scotland, have their dancing courts alongside one another on the open moors.
Such closeness inevitably leads to quarrels.
(C00ING) Such an arrangement, however, allows the females to make their assessments and comparisons much more easily.
Their decision seems to be based not only on the splendour of the males' displays and the vigour of their dances, but also where they dance.
The females prefer to mate in the centre of the whole gathering, and the male who has battled for and won that will get the majority of females.
You might think that such mass displays would be impossible in such thick undergrowth as this in Trinidad, but that's exactly what's going on here.
These little black and white birds are mannequins.
Each male has industriously cleared for himself a little dancing court.
What's more, they're all so obsessed with dancing that they don't just do so for a few weeks in the year but for nine whole months, and, what is more, for 90% of daylight hours within those months.
The males keep their courts meticulously clean and tidy.
They perch together amiably enough above their courts, but when a female appears, their mood changes.
Now each does his best to impress her with his dancing skill.
The strange noises are produced by the males snapping their wings together behind their backs and clicking the quills of flight feathers.
It seems as if they are flying backwards, because they manage to make a mid-air turn just before they land.
Mannequin dances vary greatly from species to species.
The club-winged snaps as he jumps and adopts a posture that draws attention to his scarlet cap.
Blue-crowned mannequins fly in circles around their display perches.
The golden-headed favours a backward shuffle.
That movement is elaborated further by the wire-tailed, who flicks the female across her chin with long filaments projecting from his tail.
But these long-tailed mannequins are even more extraordinary, for both are males.
The female has just landed on the right.
This is a double act.
The female will only respond if two males perform together.
But why should apparent rivals help each other? 0ne is senior.
He is the one who owns the dancing perch.
0nly he will mate with the female.
The other is his apprentice who's learning the form.
And, indeed, this dance does take some learning.
Young males start practising in their second or third year.
They get their adult plumage when they're four, but they still continue to dance with younger birds as this one is doing.
0nly when he's eight is he likely to be taken on as an apprentice by a male who owns a court.
If and when his senior partner dies, he may inherit the court and take on an apprentice of his own.
But even then he will only succeed in mating if the females are impressed by the virtuosity of his team performance.
This male antelope, a topi, is also defending a court.
It wasn't until just recently that we realised that any mammals displayed like this.
And that's just what's going on here in the plains of Kenya.
I'm sitting on the edge of just such a display ground.
Immediately behind me are the two best courts.
Each is held by a male who's trotting around, inspecting the half-dozen or so females, who also have horns, who've come to visit him today.
He sniffs one to discover whether she's ready to mate.
Within a few yards of these central courts stands a less successful male.
He has a court, but it's not the best, and no females have joined him.
The courts are so closely packed that rivals frequently come face to face on the frontier between them.
As long as they don't cross the line, their disputes are no more than symbolic.
As the day warms up, more and more females thread their way through the courts to the central ones held by the most successful males.
This young calf is accompanied by its mother.
She's ready to breed again, but not with this male, who's a low-ranking one.
He nonetheless tries his luck.
In doing so, he crosses the frontier of his court and immediately his neighbour gallops across to repel the invasion.
The successful males in the centre courts have now acquired almost more females than they can manage.
There are so many that squabbles are breaking out between them.
The least successful bulls hold courts around the edges of the display ground.
It's now hot and they're very tired, but they won't leave.
0nly by competing do they stand a chance of eventually graduating to a premier position.
But these marginal courts, being close to tall grass, are dangerous places.
A hyena.
Not all get away.
For a topi, the cost of courtship can indeed be high.
The rewards for all these displays, persuasions and entreaties, however, can certainly be great.
Yet even coupling may not be the ultimate achievement it might seem to be.
An animal may have to do even more than this if it's to ensure that its genes will pass on to the next generation and so transcend its mortality.
That will be the final trial.