Life Story

So far in Life Story,

we have seen animals face the challenges of childhood...

grow up

..find their place in the adult world...

..and win a mate.

Now, in the final chapter of Life Story,

animals become parents.

Their offspring will be their legacy to the future

if they can raise them successfully.

There is no stronger bond in nature

than that between some parents and their offspring.

Bonobos in the Congo rainforest.

They are our closest relatives.

This mother's youngster is a lifelong commitment.

He will be totally dependent on her until he's five years old.

And she will continue to support him for the rest of her life.

Their relationship may last 30 years.

Although the length of her commitment is longer

than for most animals,

she shares with many other parents the same great challenge -

keeping her offspring healthy and safe.

The bond between parents and young will be tested in many ways,

some minor, and some a matter of life or death.

And a parent's commitment may begin long before birth.

The remote northern tip of the Great Barrier Reef.

After over three decades at sea,

this female green turtle is returning to the island

where she hatched.

It's time for her to lay eggs...

..but they will only hatch on dry land.

She must leave the cool sea and enter an alien world.

Without the support of water,

she feels the full force of gravity.

Her flippers, so effective for swimming,

are almost useless on land.

But, nonetheless, she has to haul her great weight up the beach

and get beyond the reach of the tide.

Turtles time their arrival

so that their laborious journey up the beach

is made in the cool of darkness.

On any one night,

3,000 female turtles may crowd this island to dig their nests.

Now her compulsion to leave offspring may cost her her life.

The receding tide has exposed the reef, a wall of jagged rock.

It looks an almost impassable barrier

for an already exhausted turtle.

But she can't wait for the tide to return

because soon the island, under the blazing tropical sun,

will be intolerably hot.

Unless she can get over this rocky wall,

she will be baked in her shell.

This lethal obstacle course claims many victims every nesting season.

Just one slip could bring disaster.

She was so close.

But all may not be lost.

The tide is turning.

If she is completely wedged, she will drown.

But there is a chance that the rising water could lift her free.

For this breeding season,

her obligations as a mother are over.

She will never see her babies.

They won't hatch for another two months and, when they do,

they will have to survive without any help from her.

Other parents have to remain close to their young at all times

to protect them from danger.

A mother bison in Alberta, Canada.

Her calf is little more than a week old.

Wolves, sensibly, select the easiest targets.

The calves.

So bison mothers try to keep their young in the centre of the herd

where they are safest.

But that is not always possible when the herd is on the run.

The chase may continue for 25km

as the wolves try to run their targets to exhaustion.

The wolves make their choice.

She is on her own, but she's fearless in protecting her calf.

By keeping her calf close,

she manages to hold off both of her attackers.

But another wolf joins in and she can't fight three.

Now the wolves work together to wear her down.

The forest is not far off.

If mother and calf can reach the trees,

they may be able to dodge the wolves for long enough to re-join the herd.

But the attack is so unrelenting,

they can't make a dash for cover.

The wolves are beginning to tire.

She sees an opportunity to make a break for it.

Once again, she blocks the wolves' path.

And the wolves lose them amongst the trees.

But the wolves remain an ever-present threat.

HOWLING

And this is unlikely to be the last time

that this mother will have to fight for her calf.

The duties of parenthood may seem to be instinctive,

but there are some skills that have to be learned.

A troop of Hanuman langurs, 50 strong, living on a cliff in India.

This is one huge family, with members of all ages.

But there is only one adult male.

His scarred face is evidence of his violent past.

He is the father of all these youngsters.

Fatherhood for Scarface has few duties and many perks.

He gets plenty of attention from the females...

..and takes a somewhat hands-off approach to parenting.

But his protection gives his family

the safety and the space they need

to grow and learn.

The newest addition to the troop.

The baby is totally dependent on his mother and she dotes on him.

But becoming a good mother takes practice.

And a young female, a future parent,

is learning by playing mum with someone else's baby.

She seems affectionate enough.

This is valuable experience for the baby-sitter.

But now she starts to play with it.

And things get quickly out of hand.

BABY SQUEALS

She seems to want to shake off the baby.

Rescue, it seems, is at hand.

But this isn't the baby's mother,

it's another learner with even less of a clue than the last.

Eventually, the baby's real mother

decides that this game has gone on long enough.

She rescues her baby and gives it some proper motherly care.

Perhaps she tolerates the behaviour of these would-be baby-sitters

because they're close relatives.

So many females gathered together on this cliff inevitably attract

the attention of a rival adult male.

His aim is to defeat Scarface and take over his females.

He leads a group of outcast bachelors into battle.

Scarface spots them.

He has everything to lose because, if the bachelors defeat him,

they won't just take his females,

they will kill his babies.

The bachelors try to reach the high ground to launch their attack.

Scarface warns them to keep their distance,

but the bachelors continue their advance.

HARSH BARKS

Scarface grinds his teeth to show he means business.

But the bachelor leader reaches the cliff top

and grinds his teeth in response.

If Scarface loses this battle, he will lose his legacy.

Time to strike.

He targets the bachelor leader.

SCREECHING

Scarface has won.

And he returns to a hero's welcome.

But it's only a temporary respite.

For a male langur like Scarface,

parenthood is simple, but dangerous.

He has banished the bachelors and saved his offspring,

for now at least.

Success for other parents requires total dedication.

An African drongo.

She has to shade her three eggs from the scorching heat of the sun.

As soon as the chicks hatch,

she will form an immediate bond with them that is unbreakable,

whatever happens.

After hundreds of hours of incubation...her first chick.

Now the hard work really begins

because the newly hatched chick needs food.

It won't be long before one mouth is joined by two more

and this chick will then have to share what the female brings back.

Or will it?

The chick is getting rid of any competition.

It wants its mother's sole attention.

Feeding time.

Something has changed. But what?

FRANTIC CHIRRUPING

The sight of her chick's bright orange mouth

demands that she brings more food.

The egg weighs almost as much as the chick.

It's like pushing a boulder uphill.

The chick has a hollow in its back that helps it manoeuvre its load.

The mother's brood has been reduced to just this one chick

and it now has her total attention.

When she's not away gathering food, she shades the chick.

And she responds instantly whenever it demands to be fed.

Every day for over three weeks,

she brings it dozens of meals.

Her chick never seems to stop eating, or stop growing.

There is another drongo's nest nearby

and that has three chicks in it.

But they don't look quite the same as hers.

That is because she is raising an alien...

the chick of a cuckoo.

Cuckoos lay their eggs in the nests of other birds

and leave the hard labour of rearing the chick to someone else.

The cuckoo's egg matched the drongo's egg so perfectly

that this foster mother has been completely deceived.

Over at the other drongo nest, the chicks are now fledging.

Their parents have succeeded

in producing their very own next generation,

while she has raised a monster.

Her love is blind.

Back in the Congo,

the mother bonobo's long-term commitment to her baby continues.

Today, she's demonstrating

the tricky art of making a bed 30 feet above the ground,

in preparation for a midday siesta.

Lesson over, she puts her handiwork to good use.