HOWLING
This display of raw power and aggression...
..is the way by which a male chimpanzee
proclaims his high status.
SCREECHING
He is willing to fight anyone if necessary.
Male chimpanzees may become dominant in their 20s, and high rank brings
great privileges, such as the right to mate.
But not every male chimp is in the same position.
Damien, so named by the researchers observing him, is 14 years of age
and not yet old enough to be dominant.
Adolescence is a testing time in a chimp's life.
This is when he must decide if and how he will stand out
from other young males.
The chimpanzees of Ngogo in Uganda live in the largest chimp society
known to science.
And thanks to the year-round abundance of food, there are nearly
always females ready to mate.
Some years, more than 20 babies are born here.
But the majority of them are fathered by the most dominant males.
The females usually have little say in the matter.
Coercion is common.
In time, Damien may become dominant, and then he too may use his rank
and strength to gain access to females.
For now, though, he's always respectful to his superiors
and shows that by taking his turn to groom them.
He lacks the physical strength of the dominant males,
but he's old enough to mate, so he's found a different way
of getting close to a female.
This is Penelope.
She's a friend of Damien's, and he is regularly
beside her when she needs a scratch.
This is Sabin.
She, too, is a friend of Damien's.
Then there's Maya and Anna.
Damien may not be the biggest or the strongest,
but he's a popular chimp.
And it's not just a grooming service he offers.
As any mother of two will tell you, offering to play with the kids
while she has a break is a sure-fire way of ingratiating yourself.
These are not his offspring, but Damien often spends time
with Anna and her infants, on hand for a spot of childcare.
And that has led to the two of them having a special bond.
But now Anna has come into oestrus - her most fertile time.
And an older male knows that she has.
Damien gives him a wide berth.
For now, all he can do is to watch from the sidelines.
A female who's already proved herself to be a capable mother
is always in high demand when she becomes ready to mate again.
Shaking branches signals the older males desire to mate.
HOWLING
She is clearly nervous.
SCREECHING
And before he gets a chance to get really close, her calls alert
the other heavyweight males.
They will be prepared to fight for a chance to mate.
SCREECHING
Damien knows he would stand no chance against them.
SCREECHING
Despite their bravado, in the chaos, none of them succeeds
in mating with Anna.
After, the males are keen to repair their friendships...
..and Anna slips away.
With the threat of violence gone for the moment and being slightly
away from the dominant group...
..Damien finally gets close to Anna while she's still fertile.
It's not uncommon for males to develop close friendships
with females in order to mate.
And Damien has clearly got a talent for doing just that because,
two years ago, he became the youngest father in the history
of the Ngogo group...
..which proves that a little charm can go a long way.
Jungles cover just 2% of the planet, but they're home to 80% of all
land-living animal species.
To win the mating game in these dense forests,
you need to find a way to stand out, and some male animals
spend their entire lives honing their seduction techniques.
In the remote valleys of New Guinea, there are strange sounds...
CHIRPING
..and the most curious constructions
that mystified the first European explorers.
Some believed these structures had been made by the local people
in their tribal rituals.
They're ringed with moss and littered with seeds.
Strange decorations hang from the branches nearby.
But, in fact, this 60 centimetre tall construction has been built
by a bird no bigger than a thrush...
..a male MacGregor's bowerbird.
He has built this tower with hundreds of sticks,
and he maintains it year after year.
It has one purpose and one purpose only...
..to impress females.
It requires constant maintenance.
What's that stick doing there?
That won't do!
But now this.
Perfect!
This construction, his bower, dominates his life.
With maintenance done for the day, it's time to renew the decorations.
Rotting berries and...
..caterpillar droppings.
Delightful!
A female assesses his construction, and now he sings to her.
CHIRPING
As a younger bird, before he started gathering sticks...
..he collected sounds...
CHIRPING
..and now, to entice her closer, he reproduces some of them.
CHIRPING
Some are songs he has heard elsewhere in the forest...
HE SINGS
..the calls of other kinds of birds.
Others are harder to identify.
HE CHIRPS, SINGS
Chopping wood, perhaps.
A barking dog. HE BARKS
HE SQUAWKS
Even the sound of children playing...
HE EXCLAIMS
..and their frustrated parents.
The range of his mimicry, it seems, like his bower, is also a way
of impressing her.
CHIRPING
She seems to be listening attentively.
Now they begin to dance around their maypole.
He's careful not to completely reveal himself.
Excitement mounts.
And now he goes for it.
Was it too soon?
She's back...
..still interested.
Their union is brief.
She will now return to her nest, lay her eggs and raise her young...
..while he stays beside his maypole,
keeping it in good repair,
ready for more females.
On Kenya's forested mountain slopes...
..another male will also have to seek the approval of a female
if they are to mate...
..a Jackson's chameleon.
He lives high in the trees, camouflaged among the foliage.
A loner, he rarely ventures to lower levels.
One thing, however, will entice him down.
Females usually stay at lower levels in the vegetation.
But despite his panoramic vision, looking for a partner can be tricky
when your potential mate matches her surroundings so closely.
Leaf...
..or partner?
To him, it seems she's perfect and, from now on,
he's only got eyes for her.
She is less interested...
..but she's keeping an eye on him.
He could be a mate.
He's able to change the spacing between pigment cells in his skin
and so emphasise different colours.
And this is how they communicate...
..and how he hopes to court her.
His opening gambit is to turn bright green...
..and then to flare his neck to signal his desire.
Next, his signature move - a sort of staccato quickstep.
It's got her interested.
Then a bit of sidestepping.
And, lastly, a brandish of his magnificent trio of horns.
She casts a critical eye over him.
If she then turns bright green herself, he's probably
onto a winner.
Oh, dear.
She's going darker.
Just so she makes herself clear,
it's a definite no.
What now?
If he stays around, she may be more receptive
in a few days' time.
But he's not the only male on the lookout for a female.
This new male displaying his bright green isn't flirting.
Bold colours shown to the same sex are a sign of aggression.
And showing his flank means that this is only going one way.
His aim is to unbalance his opponent until he concedes defeat
by going darker.
And that's what's happened.
It's all over.
And now that his competitor has been seen off, perhaps
she's had a change of heart...
..and colour.
Alas, it's still clearly a no.
Changing colour among chameleons brings a swift end to conflict.
And when mating competition could be really violent, colour
can help to reduce the chance of coming to blows.
The jungles of Gabon in West Africa are home to the most
brightly coloured of all mammals...
..mandrills.
The males are also the heaviest monkeys in the world - over three
times heavier than the females.
This alpha male's brilliant patches of skin colour helps him
to stand out from the crowd...
HE ROARS
..whether he's advancing...
..or walking away.
The intensity of the colour is an indication
of the levels of testosterone in his body...
..and that is both a come-on to females
and a warning to males.
Only the brightest get to mate.
HE ROARS
And he has been dominant all year.
But challengers have arrived...
..also hoping that their colours will impress the females.
HE ROARS
The alpha male will have his work cut out to deal
with these newcomers.
He keeps as close as he can to the fertile females.
But a rival...
..is never far away.
The alpha assesses his opponents by their colour.
Only if a rival is really bright
will he be considered a threat.
But this one...
..is just that.
HE ROARS
The alpha proclaims his authority with a head jerk.
Grinding his teeth shows just how tense and stressed he is.
With his opponent refusing to back down,
it'll take more than body language to decide
who has this year's mating rights.
BARKING
In just a matter of seconds, the alpha has lost his crown...
..and been badly wounded.
ROARING
His reign is over.
The victor will have a rush of testosterone,
making his future bright.
The deposed alpha's colour, however, will fade...
..and, with it, his chance of mating again.
Rivalry is often dangerous, but in some cases it's the potential
mate herself who is the real threat.
If a male Australian tree-running mantis is to stand any chance
of mating, he must approach the female from behind.
And he must do so cautiously.
Something she appears keen to prevent, and that leads to a lot
of false starts and a lot of running around trees.
A whole new approach to speed dating.
So close...
..and yet so far.
Giving him the runaround tests his fitness.
A stealthy approach will show whether he is a capable hunter...
..an important skill to pass on to her offspring.
Or he could just be a cautious male
who knows that it's best not to approach any predator head on.
The thing about trying to get cosy with killers is that it's often best
to do it when they have their hands full.
Even then...
..it's prudent to approach from the rear.
But not all male praying mantis appear to take the same approach.
A male false garden mantis has also detected the scent
of a female. She's close.
She's attracting him with her seductive pheromones.
She's also much larger and heavily armed.
But to him, she smells so good.
To her, though...
..he looks good enough to eat.
The female of this species consumes her partner's head first.
His struggles are not an attempt to flee.
He's just trying to position himself properly.
He has lost his head, but he hasn't given up on mating.
Amazingly, his body, though headless, is able to find and
latch on to the female.
His abdomen will continue mating with her for several hours
before all signs of life disappear.
The strategy may seem macabre, but it gives the female
a large quantity of protein with which she can produce
even more eggs.
So, in spite of losing his head,
this male fathers posthumous offspring.
When a potential mate really is deadly, it's best to keep
a low profile.
But if that's not an option, expect to get eaten.
For others, the mating game appears to be more romantic.
Once the sun sets in the coastal forests of Malaysia, one of nature's
most magical spectacles begins.
The fading light rouses a male beetle.
For this tiny creature, just five millimetres long,
successful courtship depends on cooperation
with literally thousands of others.
It's time to get lit up.
His bioluminescent flash carries a simple message...
..I am here and ready to mate.
But he's not alone.
More fireflies begin to show their lights.
And before long, their entire tree is illuminated.
And then patterns in the flashing begin to emerge.
The fireflies are synchronising their display.
One moment, the light show appears as a repeated simultaneous flash...
..and the next...
..waves of light ripple along the river bank.
By the time the night is at its darkest, the forest edge
is throbbing with living light.
Alone, an individual male's flash will not travel very far...
..but by flashing at the same time as other males...
..his light is that much brighter...
..carrying his signal to females far and wide.
It's believed the gaps in the synchronous flashing provide
moments in which the females can respond with flashes
of their own.
It's all the encouragement he needs.
But her continual movements as he mounts suggests that she is yet
to be convinced.
He isn't attempting to mate yet.
He is contorting his body so that his lantern
is over her face, dazzling her.
It may be that he's trying to prevent her from seeing other males.
He doesn't want her catching a flash from someone brighter.
Most species of fireflies stop displaying once they've attracted
a female, but he continues. It seems his cooperation
has become a con.
His continual flashes trick his rivals into believing
he's still on the lookout with the rest of them.
She has now accepted him while his former collaborators
flash away, none the wiser.
But the fact is that many jungle courtship rituals
are still not properly understood.
The rainforests of Southeast Asia are the home of a bird that produces
one of the most dramatic and barely studied of all courtship displays.
HOOTING
Even many local people only know of its existence from the loud calls
that sometimes echo through the forest.
The great argus pheasant.
HOOTING, WAILING
A male is calling to attract a female.
He's created a wide clearing in the forest to serve as the arena
in which he will dance.
He keeps it immaculately tidy.
Though why he should choose to remove one leaf rather than another
is often not clear.
It's a time-consuming job, but he also has a special technique...
..for removing leaves wholesale.
Who needs a leaf blower when you have a wingspan
of more than a metre?
Sticks, however, still have to be removed one by one.
He must also, it seems, loosen up his feathers
and extend his gigantic wings before a female arrives.
Now he chooses a particular stick as the focus for a full workout.
He hopes to use the pattern on his splayed wings
to beguile a female.
They transform him.
There's a sound of something approaching.
Oh, dear.
A monkey.
Not who he was waiting for.
GRUNTING
And now there's a wild pig.
GRUNTING, SQUEALING
With all these interruptions, it's just as well
he's left plenty of time for rehearsals.
HE HOOTS
And there she is.
Now time for action.
One or two preliminary skirmishes.
And then...
..a spectacle that has never been filmed in the wild before.
The full display.
The lines of eyespots along each of his wing feathers
astounded Charles Darwin.
Why should they be so detailed that they have
a three dimensional appearance?
He could only conclude that it particularly pleases females.
But not apparently this one.
And now the pigs are back.
GRUNTING
Even the most spectacular displays...
..don't always do the trick.
On the Caribbean island of Dominica, another bird has found it takes
more than just pretty plumes to win over some females.
The male purple-throated carib is a hungry hummingbird.
Beating his wings around 20 times a second, he burns energy
at a phenomenal rate.
The sweet nectar produced by these flowering heliconias
is the energy-rich food he must have to keep him flying.
His species evolved in parallel with his source of food...
..the heliconia's flowers, which he pollinates as he moves
from bloom to bloom.
And now, as a result, the heliconias
produce their flowers at exactly the same time as the birds
begin to mate.
While he's busy fuelling up,
a female is also making her preparations.
She is collecting spider silk.
She uses it as an adhesive in making her tiny nest.
And now all she needs is a mate.
The male needs a way to ensure he is the one for her.
His way of doing so is simple.
Within his territory, he has five times more nectar-producing flowers
than he himself needs.
But those he doesn't drink from himself will attract females.
His problem is that it's not only hummingbirds that have a taste
for the sweet stuff.
So have bananaquits, and there's a flock of them.
He has a constant battle...
..trying to prevent them drinking his flowers dry.
The sheer size of his territory and the large number of flowers
it contains makes his job never ending.
During a rare respite in his guard duties, the female arrives to see
what he has on offer.
Not so fast.
He's no pushover.
He's not going to let any bird drink his nectar.
Chasing her away, however, is part of his strategy.
He does so repeatedly until he's certain that she really wants
to be in his territory.
And only then...
..does he allow her to feed.
As she flits from flower to flower, he shows her his true colours.
He's given her flowers and impressed her with his aerobatics.
They are now a pair.
Food is available the year round in jungles, and this enables
many species to have mating seasons that last for months.
Some, however, must wait all year for one special night.
Some frogs in French Guiana need more water in which to breed
than even the humid rainforest air can provide.
THUNDER RUMBLES
But at the very wettest time of year...
..pools appear on the forest floor.
Horned frogs spend much of their time hidden,
but the moment for action has arrived.
The rain has stopped, but this is the calm before the storm.
A pair of tree frogs in the foliage above the pool.
They need to find a leaf in a particular position,
and this will do nicely.
They lay their eggs in a sticky jelly on a leaf
above the newly formed pool.
Below, the horned frog takes a more direct route.
He heads straight in.
CROAKING
Other males have already started calling.
And before long, several species up in the treetops are also doing so.
CROAKING
All of them need pools as nurseries for their tadpoles.
CROAKING
Frogs, that for most of the year are rarely seen,
come down from the tree canopy.
Golden-eyed tree frogs take the short cut down.
CROAKING
The throat sacs that bulge out on either side of their head
amplify their calls.
Different species of males jostle for a position in the water.
LOUD CROAKING
Thousands of frogs are now calling as loudly...
LOUD CROAKING
..and as frequently as they can.
LOUD CROAKING
But what makes this place unlike anywhere else in the world
is that as many as ten different species are trying
to mate simultaneously.
As each male endeavours to call louder than his rivals...
LOUD CROAKING
..the chorus becomes almost deafening.
LOUD CROAKING
Things are becoming chaotic.
Some males in the confusion are attempting to mate
with the females of a different species.
The winner is the one with the tightest grip
and the strongest kick.
The strategy is simple - find a female quickly...
..and cling on tight.
But make sure she's your type.
And in less than 12 hours...
..it's all over.
Left behind - a soup of mixed spawn, a future for at least ten different
species of frog.
And it's time for those dangling tadpoles to join the crowds below.
Millions of frogs, some of which will be back next year,
doing their best once again to contribute to the next generation.
It is exactly because jungles are so crowded with life that animals
have to have so many complex strategies
if they're all to win the mating game.
To film courting animals in jungles around the world
took determination...
Into the forest again.
..grit...
..and a sense of humour.
It's definitely going to be a nightmare.
Argh!
THEY LAUGH
You can't leave me there!
We're in this together.
A minute ago, it was too much water, now it's too much mud.
Oh, wow!
You're well and truly stuck there, aren't you?
SHE LAUGHS
Sorry.
But there was one story in particular which posed
a unique challenge...
..filming explosive breeding in rainforest frogs in French Guiana.
Walter Hodl, the team's guide, is a herpetologist who's spent
over 25 years studying frogs in French Guiana. Explosive breeding
is a fascinating thing.
On one single day in the year, thousands of frogs homing in
on a little pond, and they are coming from the canopy,
where you never have access to, or they're coming
from the leaf litter.
You never look under the leaf litter,
and there they live all year,
and only on one or two days you see them out there in the pond breeding.
And that's what we call the explosive breeding event.
The phenomenon the crew were hoping to film happens on just one night
between November and February.
The team have chosen a four-week period over Christmas and New Year.
Cameraman Philipp Klein and Jack Hynes wait for a temporary
pond to form...
..without which the frogs won't breed.
THUNDER RUMBLES
The heavy rain begins.
It's raining! It's raining.
We've been waiting two weeks for this rain, and hopefully
it's going to stay and, you know, properly flood the forest.
Well, this is definitely good news, but it has to keep on going.
The rain started a few minutes ago, and it should rain for hours.
This is what the frogs and we like.
In the previously dry area of the forest, a new pond has formed -
an excellent frog nursery.
You can go underneath.
Stay there!
Things are looking good.
When we came here this afternoon, this was completely dry,
and it has rained all afternoon and all night.
And now we have got our pool of water.
Despite a promising start, the heavy rains stop and the frogs have yet
to make an appearance, but Christmas provides a welcome distraction.
It's Christmas Eve today, and we've got a lot of new visitors
coming to celebrate Christmas with us. And even Father Christmas
makes it to the jungle.
Whoo!
Explosive night in French Guiana.
We were just getting settled in for the night.
They're cooking a big, big, nice Christmas dinner,
and then it's just started heavily raining.
So we've come out to see how the ponds are looking,
and would be a bit of a Christmas miracle if it happens this evening.
Oh, my God!
And this is going to be a pool full of frogs.
What's happening, Jack?
It's Christmas Day, and we have just found out that the frogs
have started to explosively breed.
So it's all systems go.
Well, I think this is a good, good Christmas present.
There are hundreds of frogs there,
so it will be a fantastic night tonight.
You ready? I'm ready.
Let's go!
CROAKING
Thousands of frogs from several different species descend
upon the pond.
It's impossible to be near the pond without wearing earplugs.
The noise of the frogs calling is deafening.
Crazy!
LOUD CROAKING
Can you hear the noise? I mean, you can hear it!
It's quite a sound back there.
And we're still about 50 metres away from the real site.
How's it looking, Jack?
It's looking crazy out there - so unbelievably noisy.
I mean, this is really explosive breeding at its best,
and especially also from the acoustic point of view, it sounds
like fighter planes coming.
It's a roaring sound in the background.
You have high-pitched frogs calling, little ones, and you have also
the "grrr" frog.
So you do have a great mix, and you can hear it.
It's unbelievable what's happening here in this forest.
The crew film continuously for over ten hours.
It's a new dawn.
It's a new day. We missed Christmas!
Maybe they left... Maybe they left us some dinner.
Hopefully. But I realised we didn't eat. No.
It is almost spooky.
There's nothing - you don't see a frog.
It is silent.
It's unbelievable.
But that's what it is.
That's what explosive breeding is all about.
It happens and then it's gone.
Throughout production of The Mating Game, the team were reliant
on expert help to be in the right place at the right time.
Thanks to Walter's knowledge and a bit of luck, the crew timed
it right for the best Christmas present they could have hoped for.
Next time, it is the most fleeting of habitats...
..fresh water.
Animals that rely on it to breed must time their mating strategies
to perfection.
When they do, the results can be spectacular.