Original subtitles

In the dense rainforest of Gabon,

one of the largest, and most nimble of the primates

makes its home,

The western lowland gorilla.

Though they can weigh as much as 400 pounds,

these gorillas can easily scale trees almost 200 feet high.

Leaves and fruits from nearly 100 species of trees

are the staple of their diet.

But, for one gorilla,

life within this vertical world is especially challenging.

This young male lost one of his arms

when he was just two years old.

How can he hope to survive,

where agility and strength are vital

to a life among the treetops?

The Gabonese Republic lies on the equator,

off the Atlantic coast of Africa.

This is the world's second largest rain forest,

after the Amazon in South America.

Here the air is extremely humid,

with an average annual temperature

of around 77 degrees Fahrenheit,

and almost 60 inches of rain a year.

Branches grow in every direction,

preventing sunlight from reaching the ground.

The floor of this rain forest is always in shadow,

even during the day.

The forest teems with life,

with over 670 species of birds,

like this black cast horn bill.

And over two hundred mammals,

including the shy forest elephant,

the largest creature in these forests,

but the smallest of all elephants.

Professor Juichi Yamagiwa, of Kyoto University,

is an expert on gorillas.

He began his field work on these primates

nearly 30 years ago,

studying them all across Africa.

In Gabon, he's been tracking

one particular gorilla family for nine years.

Now, he's back to check on their progress.

The bark of this branch has been peeled by a gorilla.

He also finds a half-eaten piece of fruit.

Is it really a nut?

The western lowland gorilla is secretive, and shy,

hidden deep within these dense, tropical forests.

The bark of a gorilla echos across the forest.

Yamagiwa begins a low grunt,

imitating the greeting sound of a male.

He doesn't want the gorillas to feel threatened.

The team spots a male,

a western lowland gorilla.

These primates are the largest tree climbers in the forest.

Navigating the branches of African teak,

and other trees, with ease.

Scientists believe that gorillas know, from experience,

which branches can support their weight.

This gorilla balances its heavy weight on a single branch.

The team needs to go deeper into the forest,

in search of the family.

They're close.

Yamagiwa approaches cautiously,

uttering a low grunting sound.

He doesn't want to frighten the ape.

Several other gorillas emerge from the undergrowth.

This is the family Yamagiwa was hoping to find.

The father, and dominant male, is called Papa Gentil,

meaning, "nice daddy" in French.

Papa Gentil weighs almost 400 pounds.

His most striking feature is

the swath of silver hair across his back,

the mark of an adult male.

These gorillas are called silverbacks.

The 23 members of this family

include six mothers and their offspring.

The mothers all come from different troops,

but the young are all Papa Gentil's offspring.

Once they're weaned, the parenting duties are passed to him.

Play is an important part of growing up gorilla.

So is imitation.

The little ones watch and learn from Papa Gentil.

Under the guidance and protection of the dominant male,

a gorilla family always stays and moves together.

Every day they walk around 1 1/2 miles

in search of fruit, leaves, and even termites and ants.

Even the children are masters at tree climbing.

Since they are heavy creatures,

they can't all climb the same tree.

But, there is plenty of fruit to go around,

and different techniques for getting it.

To save time,

this gorilla simply pulls the neighboring tree closer,

and hops on.

This way, he doesn't need to go down the way he came up.

A mother with an infant shifts her weight

toward a neighboring tree,

causing her tree to bend.

She easily moves from one tree to the next,

with baby clinging tightly.

But, one member of the family is missing

from among the trees.

Dodo, a six year old male.

Four years ago, Dodo was a feisty youngster,

imitating his power in a show of power.

Though just weaned from his mother,

he was still dependent upon her for milk.

Then, Dodo was attacked by a male outside of the family,

trying to steal Dodo's mother for a mate.

The gorilla who took his mother away

most likely saw Dodo as a nuisance,

and attacked him.

Dodo lost both his mother, and his right arm.

Shortly after the attack, Dodo was covered in cuts,

and was missing his right arm, just below the elbow.

Without his mother's milk, Dodo's chances were slim.

It was Papa Gentil who saved him.

Without the use of his arm,

he tended to lag behind the family.

Whenever that happened, Papa Gentil always waited for him.

The family travels in the open grassland,

between two forests.

They're an easy target for predators or hunters.

They need to cross as quickly as possible.

The family could have abandoned Dodo, but chose, instead,

to protect and nurture the injured youngster.

Yamagiwa believes this show of deep compassion

is what keeps the entire family strong and safe.

But, can a gorilla with such a handicap

make it, in a world so dependent upon climbing?

In fact, not all gorillas inhabit dense rainforests.

Their cousin, the mountain gorilla,

makes the ground it's home.

They frequently inhabit the slopes of dormant volcanoes,

living at high altitudes,

where tall fruit trees rarely grow.

These primates are herbivores that feed on plants and grass.

How did the two different species come to live

in such different environments?

The territory of the western lowland gorilla

is the lowland tropical rainforest,

near the western coast of Africa.

12 hundred miles east are the mountains of central Africa,

home to the mountain gorilla.

Over 20 million years ago,

African tropical rainforest

covered a much wider area than today.

Around 10 million years ago, a massive geological shift,

deep within the continent's crust,

made the land of east Africa begin to rise and crack.

This trench became an enormous valley.

Magma pushed to the surface,

creating a gorge nearly two miles deep.

This was the birth of the Great Rift Valley.

These newly created high elevations

caused dramatic changes in climate.

East Africa,

which had been covered in rich, tropical rainforest,

dried up.

The forest disappeared.

The mountain gorilla began eating grass,

while the lowland gorilla continued

to forage for food in the trees.

Their tree-climbing lifestyle, the same as their ancestors,

never needed to change.

Western lowland gorillas spend several hours

of the morning eating.

They'll take a break in the middle of the day,

then eat again until dusk.

It's late August,

the height of the dry season.

Yamagiwa searches through the forest

looking for places that Papa Gentil might bring the family.

He finds something.

Gorillas love to eat this fruit.

And here in this part of the forest,

these trees are few and far between.

This tree is filled with a cherry-like fruit.

Yamagiwa checks to see how ripe it is.

The fruit is ready to eat.

This is the perfect spot

to catch Papa Gentil and his family.

Six surveillance cameras are set up around the tree.

The next day, the team gets results.

An ape arrives, but it's not a gorilla.

It's a chimpanzee.

Just like gorillas, they love this fruit.

Half way through it's meal,

something in the bushes grabs its attention.

The chimp decides not to stick around.

One minute later, the gorilla family arrives.

Papa Gentil barks, and scurries in the direction

of the chimpanzee.

The youngster that arrived first had noticed the chimpanzee.

When he tried to move closer to it,

Papa Gentil made a dash.

Papa Gentil went to stop the youngster

from going anywhere near the chimpanzee.

There's no particular hostility

between gorillas and chimpanzees,

but they tend to keep each other in check,

because they both forage for the same fruit.

Now, the family is ready to eat.

An infant clings securely to its mother.

Next, it's Papa Gentil's turn.

Because this tree is so slender, with fewer branches,

only the mother and Papa Gentil make the climb.

This mother's infant, the youngest of the troop,

is not even two months old.

Priority is given to a nursing mother,

who needs to consume more to maintain her milk supply.

For Papa Gentil, so much fruit in one place

is a special treat.

Full grown males need to eat about

45 pounds of food per day.

As for the others, there's more than enough

lying on the ground.

And Dodo's got plenty to keep him happy.

He's developed his own way of foraging,

and he's got a healthy appetite.

There's a reason why so much fruit is falling.

When eating, using their powerful strength,

gorillas often break off entire branches.

Breaking branches helps to complete an important process.

After a few days, the fruits on a broken branch

will turn red, and ripen.

If left on the tree, this fruit will stay green,

and take its time to ripen.

But, when a branch is broken, ripening begins immediately.

Branches with dead leaves are a sure sign

of gorilla activity.

And, broken branches allow for a

constant supply of ripe fruits.

As they feast, gorillas often drop fruits,

or entire branches to the ground below.

Dodo is reaping the benefits.

Dodo continues picking up fruit

until Papa Gentil comes down.

Then, the family heads off.

As they move through the forest,

something's different.

This time, instead of lagging behind the rest of the troop,

Dodo's in among the leaders.

He seems determined to hold his own within the family,

and Papa Gentil and the others,

seem just as determined to keep him strong.

Yamagiwa has seen signs that Dodo has been making progress.

But, he wants to find more evidence

that Dodo has a chance to survive into young adulthood.

Yamagiwa and the team see the family just ahead.

Dodo is with a sibling.

As the team tries to move closer, they can feel tension.

The gorillas are on alert.

One of the mothers starts howling.

Then, Papa Gentil dashes towards the team.

He's warning them not to come any closer.

Although the family splits up when climbing trees,

on the ground they stick together.

Papa Gentil is ready to guard his troop, at any cost.

Yamagiwa and his team want to know

why the family seems so agitated.

The team sets up surveillance cameras.

One is placed on a path the gorillas often take.

At first, nothing seems out of the ordinary.

A mother and her baby pass by the camera.

They don't seem to notice it.

Another gorilla slowly approaches the camera,

but doesn't seem to be threatened by it.

But, as day turns to night,

the cameras show a different story.

A leopard appears.

Leopards are the gorillas only wild predator.

This could be why Papa Gentil and the family

were so tense, and aggressive.

The next morning, at the research camp,

there's another ominous sign.

A gorilla appears from behind a cabin,

a full grown male,

alone.

With no family,

these gorillas are known as solitary gorillas.

This gorilla is a little unusual.

He has no fear of humans.

He may be used to people,

because the camp site is within the territory he roams.

Male gorillas usually become silvery at about 13 years old,

when they leave their families to go off on their own.

Solitary gorillas live their bachelor years

roaming the forest.

Without a family to protect,

they live a relatively care-free life.

Soon, he'll begin to search for a mate.

They advertise their strength through their

unique chest beating displays.

Solitary gorillas pick out mature females

living with their family.

Sometimes, they will try to steal a female.

They can even attack infants, or youngsters,

in order to abduct a female.

This is what happened to Dodo.

And another attack on Papa Gentil's family

could prove very dangerous for the vulnerable Dodo.

It's now mid-September.

The three month long dry season is nearing its end.

It's the first rain in a long while.

Large raindrops moisten the forest foliage.

After the rain, flowers grow brighter.

The sky clears, and the gorilla family resumes eating.

As the rainy season approaches,

the fruit becomes sweeter, and more plentiful.

All the gorillas in the family

are picking fruit in the trees.

All except one.

Dodo is sitting below, alone.

This time, there's very little fruit lying on the ground.

He's been sitting there for some time,

but then, he gets up.

He's now 50 feet above the ground,

looking for young leaves.

He holds on to a bunch of leaves

using his injured arm.

He goes further up.

This is the evidence Yamagiwa has been looking for.

It's been four years

since Dodo was attacked, and lost his arm.

He's developed, and mastered, a great many skills

a young gorilla needs to survive in the rainforest.

Perseverance, and a keen intelligence

have brought Dodo a long way.

But, his greatest strength may be

from the strong support of his father,

and the rest of his family.

Their encouragement and compassion

will give Dodo the best chance to flourish

in this tropical world, high in the tree tops,

in one of the densest, and most wild places on earth.