Original subtitles

East Africa,...

..and something is stirring in the grass.

These male widow birds are desperately flinging

themselves into the air...

..all to try and impress the ladies.

One female flies in for a closer look whilst

he proudly shows off around a grassy palace, built purely for effect.

Animals will go to extraordinary lengths to win a mate.

There are show-offs and romantics...

..singers and dancers, even some who resort to brute force.

The challenges of winning a perfect partner create some of the most

beautiful and spectacular sights in the natural world.

Yet it's also a far more complex contest than we might imagine.

Beneath the surface lies a web of intrigue, surprising strategy

and fascinating biology.

Science is slowly revealing what it takes to win at the mating game.

The Arctic, millions of square miles of empty ice.

Polar bears are normally solitary.

You might think that even finding a partner in this desolate

landscape would be a real challenge.

But they have an excellent sense of smell

and can detect another bear from miles away.

Male bears can spend weeks tracking the scent of a female

who's ready to mate.

They sniff closely to size each other up.

She'll raise her cubs alone, devoting herself to them

for two, even three years. It's a huge commitment of time

and effort, so it's vital to pick a male who will provide strong

and healthy genes for her offspring.

It looks as though she's going to put this potential suitor

through his paces!

She leads him up and down the slopes.

It's as if she's testing his fitness.

They start to play.

Courtship is one of the few times that adult animals play together.

This slope is rather steep for the heavier male.

It's no good. He can't quite manage it.

But she seems to have decided that he might be The One...

..whilst he seems to have lost interest.

It's her turn to do the chasing

and she's got a few tricks up her sleeve.

That was enough to entice him up again!

Now that she's reeled him in,

she goes straight back to giving him the run-around.

Choosing partners who can prove how fit and strong they are

is a useful strategy in the mating game, and it's often the females

who do the choosing and the males who have to make all the effort.

In the tropical forests of New Guinea, one male is dedicated to

making an unforgettable first impression.

The six-plumed bird of paradise is cleaning his display ground.

He obsessively tidies every fallen leaf.

His stage must be meticulously tidy

for what will be an incredible performance.

A few attractive berries to help decorate the floor.

His final touch is hardly ever seen.

Might he think he's found a bit of old snake skin?

Some scientists believe he's trying to add the scent of a snake to

ward off predators. For others, it's a cleaning cloth

and he's polishing a perch for a female.

Later, he uses a bigger bit of rag and does the same.

Only strong, healthy and well-fed males can afford the time

and effort for the most meticulous preparation

and, in theory, they're the ones with better genes to pass on.

He'll have a highly critical audience, so it's time to

rehearse the main act.

His dance steps perfected,

he's ready to start the show for real.

He spots a female nearby,

so quickly goes to get more berries to tempt her in.

Disaster! He's left his polishing rag on the dance floor.

It's perfect for her nest! She flies off without even

seeing his dance. He delivers his berries too late.

He never got a chance to win her heart

and he lost his precious polishing cloth.

Back to work.

For a choosy female, displays are an excellent way to assess

the qualities of a potential partner.

They're full of clues as to how good the male's genes might be.

Physical features, like those extraordinary feathers,

might also be a sign of how strong and successful this male is.

It's all a matter of taste.

Different species are attracted to different features.

As fussy females favour particular attributes, they become exaggerated

over generations, leading to ever more elaborate and extreme displays.

Fancy feathers, red faces,...

..blue faces,...

..large noses.

Beauty is all in the eye of the beholder...

..and it's not just stunning visuals that can win a mate.

Off the tropical paradise of Tonga, you can hear

perhaps the loudest love song in the world.

WHALE SONG

Male humpback whales repeat each other's songs

and add to them, so they become ever more complex and beautiful,

showing off their memory as well as sheer volume.

Listening carefully to this song is a female humpback whale.

She's here with last year's calf

and is ready to conceive another one.

He stops singing and follows her.

He may sing to her again but not if he thinks other males are close by.

They start to get to know each other. It's an old-fashioned,

slow-motion waltz.

Such beautiful movement is rarely seen.

Dance in the animal world is little understood.

But their courting ballet is about to be cut short.

Rival males have detected that something is going on.

They arrive in force, a mob on the dance floor, set on disruption.

Each male tries to get beside the female

and to intimidate the others.

The 35-tonne males are set on a fight.

Animals that can seem so tender in a moment become so aggressive.

The mating game has become a battle.

They smash into one another. They tail-slap and bellow.

Most of this is just show, throwing their weight around.

It's over. The biggest male has won.

She will accept the outcome,

the male who's most likely to father the strongest offspring.

In the end, it was fighting that proved a better test than

singing or dancing.

Competition is a big part of the mating game and, inevitably,

it can lead to physical aggression.

BELLOWS

Full of testosterone and laden with weaponry,

males push each other to the limit.

Size and strength are the ultimate test of virility,

but fighting is a dangerous, even life-threatening, strategy.

So, animals will go to great lengths to avoid a fight if they can.

American bison graze peacefully together for much of the year.

But when the mating season arrives, the atmosphere changes.

The males begin to taste the air to pick up the scent of any female

who might be ready to mate.

Before a fight, competing males walk in parallel,

assessing one another.

Pumped up with testosterone,

they paw the ground to show off their strength.

They spray the earth with their urine and then roll in it

so that they reek of their own hormones.

These ritual displays can put off rival males without having to

resort to a potentially dangerous fight.

But it doesn't always work.

Even then, most fights are resolved in a matter of seconds.

A few, however, escalate into full-scale battle.

Weighing almost a tonne, they use power and speed to try

and push each other off their feet.

This male is lucky to escape a fatal stabbing.

For the winner, the prize is a whole harem of females.

But, sometimes, the way to win is not to fight for females

but to fight for something the females want.

On the other side of the world, an idyllic English riverside is

the setting for one such story.

Here, there is a creature that flirts with suicide

to woo his paramour with the perfect gift.

The delicate Banded Demoiselle knows that what every girl wants

is fast-flowing water, rich in life-giving oxygen,

as the best place to lay her eggs.

Each male, in his shining, metallic armour, is prepared to

fight for the best patch in a graceful, aerial competition.

The victor has won a patch where the river riffles round a fallen branch,

faster-running water that is just what the ladies are looking for.

But how can he prove that this is a good spot?

He flings himself at the water, using his own body to show the flow.

It's a high-risk strategy.

He might drown or be snatched by a hungry fish.

If she's satisfied, she'll accept him.

All his hard work has paid off.

She gives their eggs the best possible start in life,

laid on plants in oxygen-rich water.

A true romantic hero who has risked his life,

and all because the lady loves the perfect place to lay her eggs.

So, some males fight for females, whilst others,

like the Demoiselle, fight for something the females want.

And there are just a few animals where males fight for a prize

that seems almost arbitrary.

Topi, an African antelope, gather each year for a very unusual

and highly ritualised contest.

The males start by putting on war paint.

By plastering their horns with mud, they're trying to be more

intimidating to other males, and maybe more attractive to females.

The dirtier, the better.

The males compete in a loose circle called a lek.

Each fights for a patch of land as close as possible

to the centre of the arena.

There's nothing particularly special about the middle, but in the

ritual of the topi's mating game, it's become symbolically important.

They fight for the centre because, well, because it's the centre.

Eventually, each male has won his patch,

and the females are more likely to choose a partner who is

closer to the heart of the arena.

The mating rituals go on for many days.

The males dare not leave their territories

in case rivals should claim them.

And they have to fight repeatedly to retain their position.

As the days pass, they become ever more exhausted.

There is a real, physical cost to this competition.

Hyenas are quick to take advantage of the weak and exhausted topi.

Yet, in spite of the circling hyenas,

the male topi will stay close to their places on the lek.

To flee would mean losing any chance in the mating game.

It's a risky game to play.

Some males choose a rather different strategy.

In the dry forests of Madagascar are some that have chosen to be

lovers, not fighters.

Ring-tailed lemurs live in troops of around a dozen individuals

in which the females rule the roost.

This morning, the ladies can choose from a line-up of hopeful males.

Welcome to the lemur lounge bar.

The boys are on parade, hoping to be the chosen one.

They are sizing each other up, this particular morning, with excitement.

One of the females is on heat. It's her choice and she's unpredictable.

A chance for fatherhood is up for grabs. Fights quickly break out.

The object of their affection just sits and waits.

Whilst the squabbles continue,

one sneaky young male sees an opportunity to make his move.

He hopes to win her heart by more subtle means.

With an air of nonchalance, he settles down

and begins to smear scent onto his tail from glands on his wrists.

The perfume he wafts over her will tell her a lot about what

he has to offer as a potential partner.

And he just might offer something that the other males don't.

He may not be the strongest fighter,

but very latest science suggests that his scent might contain

clues to a different strength, his ability to fight illness

and parasites which he could pass on to her offspring.

She's still not convinced.

Maybe she should wait for the outcome of the fight.

So, she leads him off to somewhere quieter.

His sneaky seduction has finally won her over

and they head off for some undercover love.

Whether by fighting or by sneakier means,

it's often males who seem to do the hard work in the mating game.

But it's not always as one-sided as you might think.

These mountain gorillas are headed up by a dominant male,

the silverback.

He's head of a family of females and youngsters.

It will have taken him many years to win this prestigious position.

GORILLAS HOOT AND SCREAM

There is a young female who's recently joined his group.

She wants the silverback to father her children.

She's just come into season and she has only a couple of days

when she's fertile.

There's no time to waste

but she's going to have to work hard to get his attention.

She stares at him, a brazenly flirtatious act in itself.

She tightens her lips into a smile and gazes straight into his eyes.

This is gorilla seduction at its least subtle.

But he doesn't seem to be won over by her shameless tactics.

The whole family watch to see what happens next.

The young female decides to try a different tactic.

There are two teenagers, black-backed, immature males,

and she flirts with them.

She positions herself between the two rival boys.

Both are interested in her.

She's a tease.

As she joins one, the other watches, grunting in jealous fury.

She solicits both males but doesn't actually mate with either.

She only has eyes on the big prize and, sure enough,

the silverback hears and comes charging in.

With a little subterfuge, she gets her man.

The silverback will offer more than just good genes to her offspring.

Any children that are his will get his protection

as part of the family.

Perhaps best to make absolutely sure.

It's all for this, a helpless mountain gorilla baby,

one of only a few hundred left.

The family bonds in mountain gorillas are strong.

The silverback's role as father goes beyond protection.

He's babysitter, punch ball and role model, too.

When both parents stick around to protect

and rear the offspring, the mating game becomes more complex.

It's no longer just about strong and healthy genes

but about choosing a partner who will help to raise the youngsters.

And that can seem like finding one in a million.

The party here, on Lake Bogoria in Tanzania, is perhaps

the greatest gathering of courting couples in the animal world.

Thousands of flamingos dance together,

all looking for Mr or Mrs Right.

Eye colour and feathers are important. The brighter, the better.

Once you've caught someone's eye, it's about choosing a partner

who will be loyal, who will stick around.

Flamingos seem to prefer birds similar to themselves.

But the dance may reveal much deeper insights into each other.

Many animals find symmetry attractive,

and the mirrored movements

and co-ordinated head turns may help find a mate that is more compatible.

It's vital to make the right choice.

Flamingos nest in the middle of soda lakes.

These are swamps of caustic mud.

It's one of the hottest places on Earth.

It's a trek to the nearest food and fresh water,

and you can't leave the nest in the sun.

That means raising the chick is impossible for a single parent.

Working together is crucial.

It gets up to 50 degrees Celsius out here.

This is parenting at its toughest,

so, the choice of partner made in the dance needs to be right.

After a short time, the chicks form a creche,

safety in numbers as they learn to stand on their own two feet.

And, eventually, they set off to find fresh water.

Their parents abandon them, though they're still only chicks.

They have to find their own way

out of the hellhole in which they were born.

They have no family to help them now, only each other.

But there are animals where the family is a far more

permanent institution.

Here, the mating game needs teamwork to win.

HOWLING

February in Yellowstone, bitterly cold and food is scarce.

Alone, a wolf would struggle to hunt.

Their prey, elk, are many times a wolf's size,

so, to survive out here, the wolves work as a family team.

Offspring stay with their parents for many months,

learning how to survive and to help raise the next litter.

The alpha couple need their help.

Winter is mating season and they need to be fit and healthy.

The male is dark, the pack mother grey.

They defend the group and lead the hunts.

BUGLING

The pack spreads out to head off the elk.

Hunting strategy is passed down, learned

and refined within families and generations.

The father leads one team. The mother intercepts a panicking elk.

BUGLES

They all share the spoils.

But all is not quite as collaborative as it seems.

This pack strategy works well for the alpha couple but not quite

so well for last year's offspring.

The youngsters could have their own pups, but for the alpha couple,

that would mean more mouths to feed and less for their litter.

So, the alpha couple

will actively discourage last year's offspring from mating.

But one of their daughters has other ideas.

Skulking behind the pack is a lone male wolf.

He has no territory of his own but follows the family,

scavenging leftovers and looking for opportunities.

He's spotted one, the young daughter.

The intruder could be in with a chance, as long as he's not caught.

The pack leader could kill him.

HOWLS

While the pack is distracted by a bison,

the temptation for the young female is too great,

and she sneaks away to join the mysterious stranger.

It's risky but it could be her only chance to get close

to a potential mate.

When mating, wolves lock together,

unable to separate for half an hour to ensure fertilisation.

Not so good if you're about to be caught by your dad.

The affair was always destined to be a short one.

After a painful separation,

her new mate is chased away with his tail between his legs.

The wayward daughter is chastised for her behaviour.

Eventually, though, she'll be accepted back into the family.

Having her own pups would be the best way for her to pass

on her genes but it might threaten the success of the alpha couple.

There's a tension between them.

And the more we learn about how animals behave,

the more it seems that behind the facade of seemingly perfect

animal partnerships lurk darker secrets,

the truth of which are only now coming to light.

Lar gibbons in the forests of Thailand.

They seem to be the perfect couple, musical and monogamous.

WHOOPING AND SINGING

Their duet is a renewal of their partnership

and proclaims their home territory.

They stay together to raise a family.

But appearances can be deceptive.

They're surrounded on all sides by neighbours,

and gibbons can sometimes stray.

It turns out that as many as one in ten matings

may not be with their partner.

Some scientists think there may be a reason for a female's infidelity.

A quick liaison may serve to convince other neighbouring

males that they could be the father of her offspring,

and this might stop them attacking the youngsters.

Maybe a little infidelity actually helps protect the family.

Whatever the reason for straying,

their affairs don't seem to be a problem for their partnership.

They'll remain together.

And this is not the only example of a flexible relationship that

can be more advantageous to animals than a purely monogamous one.

The dry forests of western Madagascar are a harsh place

to bring up a family.

But there is one bird who's come up with a cunning plan.

This is the vasa parrot.

She has a tree hole full of chicks,

but food is scarce and she can't feed them all by herself.

From a high perch, she issues a summons across the forest.

BIRDCALL

She's not the prettiest-looking bird.

During breeding, her sleek, black feathers fell out

and her skin underneath is orange.

But her trashy appearance doesn't deter suitors.

A male answers her call.

They've been courting for many weeks and mated regularly.

They greet with a head-swaying dance that seems to say

"you are the only one for me".

Then he passes food to her.

Suddenly, he leaves and another male turns up.

And another male.

She has mated with them all and she accepts his offerings, too.

In fact, she may have up to six males on the go at once.

They all feed her.

Each male may believe that he is the father to her chicks.

With a graceful tete-a-tete,

she seems to reassure each of them that he is the special one.

Then it's back to the nest with all the food.

Her clutch is of mixed parentage.

Perhaps here, three of the males out of the six are genuine fathers,

and the other three duped.

In this game, she is the real winner with several doting fathers

to help feed her children.

A cunning ploy.

So, does everyone cheat at the mating game? Well, maybe not.

True monogamy, animals that stay together for ever

and remain faithful, is certainly very rare.

But there may be a few perfect partnerships.

One may be found in New Caledonia in the South Pacific.

These are Kagu,

flightless birds that stay together as a couple for life.

Both parents work together to look after one chick.

This is the dad, pitting his wits against a worm.

Spot the chick.

The camouflage is effective.

Less effective is getting the food in.

Feeding babies can take a lot of patience.

Some of the young from previous years stay in the territory

and help defend any chicks from predators or neighbouring Kagu.

Several birds all help guard one chick.

SQUAWKING AND SINGING

Each morning, they sing together.

They work as a team and chase away any intruders.

SQUAWKING AND SINGING

The Kagu's relationship is solid and the bonds of commitment

are passed down to the offspring, forming a strong family unit.

But the Kagus also seem to be quite the romantics.

Each year, the male rekindles the flame with this lifelong mate.

She's seen it all before but it's still important to remind her.

After all, no-one likes to be taken for granted.

They may be committed for life

but it seems he still wants her to know

that she's the only one for him.

Throughout the animal kingdom, the mating game is

full of extraordinary behaviour and surprising sophistication.

Even fighting isn't simple but overlaid with ritual and sacrifice.

For some animals, it's all about playing the field.

Others may be searching for more commitment in a partner,

one who will stick around.

Some are carefully chosen for a brief liaison.

Others form bonds that can last a lifetime.

And there are a few that remain truly faithful.

But is it all just a game or is there ever something more?

Do these bonds ever go beyond physical need?

In the heart of Australia is a rather unlikely

candidate for ultimate animal romantic.

This is a shingleback, a skink,

known here in Australia as the sleepy lizard.

A female catches the eye of a male.

He courts her by gently nudging her and licking her.

They will stay together for two months

and then they'll separate for the rest of the year.

But despite this time apart, the couple's bond remains strong.

The following year, they will somehow

manage to find each other in order to mate once more.

As far as we know, they remain faithful for the rest

of their lives, sometimes for more than 20 years.

Even when one of them dies, they're reluctant to move on.

Shinglebacks are slow and vulnerable.

If one half of a pair gets run over,

the other has been seen waiting by its side for days.

It seems the bond between them endures, even after death.

Surely, this is more than just a mating game?

Certainly, there's much more about animal relationships

that still waits to be discovered.

Subtitles by Red Bee Media Ltd