-As animal babies approach the end of their first year, they must take on the most complex challenges of their lives.

In Kenya... [ Safina trumpets ] ...on her first birthday, an elephant calf must work out how to feed herself.

[ Trumpets ] At the edge of the Arctic, a fox cub approaching adulthood must learn how to make it through a brutal winter.

In Sri Lanka, a 1-year-old macaque must learn the skills to survive beyond his mother's protection.

And one of our closest cousins, a mountain gorilla infant, must learn the coordination to explore Uganda's forest kingdom.

Like all babies, these young animals will have a first year filled with joy, love, and play.

But there will also be challenges... [ Elephant rumbles ] [ Macaques chitter ] [ Sea otter barks ] ...sometimes on a daily basis.

[ Hyena growls ] [ Macaques squeak ] [ Thunder rumbling ] [ Roars ] -I'm quite nervous because lions don't like hyenas.

-To tell the stories of these magical months, four renowned wildlife cinematographers will follow the lives of our baby animals as they grow and develop.

-This is pretty unreal, actually.

I get treated with a little baby boy.

He's just a few hours old.

-[ Lowered voice ] This is the stuff that makes elephants so exciting.

It's just the way we are.

-This is the story of what it takes to survive in the wild.

This is their first year on Earth.

-It's almost like seeing your kid ride a bike for the first time.

-In southwestern Uganda, an unparalleled island of forest covers mountaintops close to the equator.

It is known as Bwindi the Impenetrable.

Cameraman Vianet Djenguet rose to prominence through filming endangered wildlife in Africa's forest kingdoms, and he is here to follow the progress of one of the rarest babies in the wild, one of possibly only 50.

He is tracking her family with the help of Dr. Martha Robbins of the Max Planck Institute, who has been unlocking the secrets of this forest for more than 20 years.

Their tracks lead to a unique habitat in its heart -- a swamp.

[ Gorilla grunting ] The family are Bwindi mountain gorillas.

-I just spotted Nyakabara.

-1-year-old Nyakabara has a bracelet of white fur, never seen before in mountain gorillas.

She is the daughter of the muscular young silverback who protects this group of 13.

They are so closely related to us, that Vianet must wear a mask to prevent the spread of any human diseases.

-She's just, like, piggybacking on her mother's back.

-At 16 1/2 pounds, Nyakabara is now more than three times her birth weight.

Born a year ago, she spent her first few months just sleeping and suckling, attached to her mother and absolutely helpless.

Now she is alert, active, and can ride on her mother's back to see what's going on.

Vianet is here to see if as a 1-year-old, she is developing the vital skills to forage for herself, but it's not going to happen in the swamp.

The food here is for experts only: thistles.

-So I'm being very careful with how I hold it because it's covered in spines, but the gorillas love this.

It's very high in protein.

-Right.

-And there's not very much of it in Bwindi.

-Oh.

-But the way they eat it, it's amazing because they take their hands and they just go all the way up to get the leaves, and then they fold it a bit, and they put it in their mouth.

-Oh.

-But even if you watch them chew, they're kind of chewing like this, and so I think it's a little bit painful for them to eat it.

-The nutrients thistles provide mean it's worth the effort and discomfort.

Nyakabara won't be capable of this level of manual dexterity for another 3 years.

Vianet wants to see if she can master the more basic techniques of food manipulation.

And that's something she learns by watching her mother handling around 100 different food plants.

[ Branch snaps ] After around 8 months of age, mothers become less protective of their babies, and increasingly let them work out how to do things for themselves.

Woody vines are an abundant food plant in the forest, but it's the pith inside the bark that the gorillas eat.

Nyakabara learns by observation, not instinct.

She has to find a way to get the same end result by herself by trial and error.

-Look at that.

Look at that.

I wasn't expecting this.

She's trying to strip the bark.

This is actually the first time I've seen her doing this.

That is a moment -- a milestone in Nyakabara's life.

-Nyakabara has the basics covered, but the real challenge of growing up in Bwindi is its trees.

Uniquely, Bwindi mountain gorillas spent a lot of time high up in trees collecting nutritious fruits.

At just 2 months old, Nyakabara and her mother fell from a tree.

[ Branch snaps ] [ Thud ] By 8 months old, she started to climb for herself but was very shaky and kept under close control by her mother.

Now as a 1-year-old, her mother gives her free reign to explore.

-[ Laughs ] -Nyakabara's real challenge is to combine climbing and foraging skills.

-She literally climbed that tree, away from her mother.

She's doing her own exploring, her little world.

Oh, man.

Oh!

Look at that.

Look at that.

-African star apples have just come into fruit and make the perfect snack.

-This is -- this is exactly what I was expecting her to do.

Look, chest beating as well.

[ Laughs ] Brilliant!

That is just saying, "I'm 1 year old now, right now.

I've reached my first year on Earth."

-It will take 3 years before this precious baby can survive here on her own.

But over the next 12 months, she will hopefully perfect the skills required to move freely and confidently 100 feet above the ground between the trees of the Bwindi Impenetrable Forest.

Some animal babies will stay within their families for many years, but others, at the edge of the Arctic, must quickly forge their own path.

The Hornstrandir peninsula is the most remote corner of Iceland.

It's September.

Colder weather is taking over from the short summer months.

In just a few weeks, this valley could be blanketed by snow and ice as the long, desolate winter returns.

Fela is the only white Arctic fox cub in a litter of eight.

At just 4 months old, he is almost adult size, but he is not an adult yet.

He still relies on his parents for food.

Fall is the cutoff time when cubs have to learn to get the food they need to survive their first winter.

Wildlife cameraman Colin Stafford-Johnson has decades of experience filming fox behavior and is here to see if Fela has the resourcefulness to come through this crucial period.

-He purposely came downwind of me so he could give me a really good sniff to see who I was, and he seemed happy enough.

-Fela was born with acute senses of smell, hearing, and sight.

They are all focused on the moments his parents return from the hunt with a potential meal.

But at this time of year, food is in short supply.

Back in the summer, breeding seabirds provided food for Fela's family, but there was never enough to support a whole litter, and competition between the cubs was intense.

[ Cubs barking ] On average, only half will make it through their first year.

-I'm really pretty convinced, at this stage, that there are only four youngsters left.

I hoped that a few more might make it through.

Both parents have been rushing around this valley, supplying food as much as they could, but the food is coming to an end, and they have to look after themselves.

They have to put on enough weight to condition to get through the winter.

-The white mother of the cubs has dug up a dead seabird she had stored.

Now she has to decide if she will give it up for her young.

A dark cub is first on the scene.

But Fela has spotted her, too.

[ Cub whining ] The dark cub is begging, but the vixen won't release the meal.

Fela flicks his tail and also calls to demand food... ...but he too is rejected.

The vixen leaves behind her hungry cubs.

This is a turning point in Fela's life.

He now has to find his own food if he is going to survive.

-This is a really dangerous time now for these young animals.

[ Fela whines ] -Everyday, Fela must try to find out what he can eat... ...things he may never have tasted before, so he needs to investigate everything within this landscape.

-He's still acting like a puppy.

The quicker he realizes he's now on his own and fully independent, the better.

[ Wind whistling ] The first snowfalls have arrived on the hilltops already.

It's a real sign of things to come, and it's a real reminder of how little time Fela has.

-Freezing temperature and biting 100-mile-an-hour winds can quickly bring hostile winter conditions.

-So alert to everything, every little movement.

He looks to be searching the rocks for, I think, spiders.

-Fela's instincts are kicking in.

-I really came here to witness the early days of Fela's independence, and that's exactly what I'm seeing right now.

Of course, you think, "Well, a spider, it's not exactly like eating a seabird or something," but they're full of energy, full of nutrition, and if he gets enough of them, it'll be plenty to sustain him.

-In the remaining days of fall, Fela will eat as much as he can to build up his fat reserves.

-It's amazing how in just a short time, he's gone from that sort of little ball of fluff that first emerged above the ground to the resourceful, boisterous little character that he's become.

He'll get through into next spring, and then it will be time to find a mate of his own.

And hopefully these valleys will resound to his calls in the years to come.

I think there's a good chance they will.

[ Bird chirping ] -It's June on the tropical island of Sri Lanka.

In a northern province lies the bustling town of Polonnaruwa... ...and at its heart, the ruins of the island's ancient capital, a sanctuary that is home to over 1,000 endangered toque macaques.

Sue Gibson is a wildlife cinematographer inspired by the complex lives of primates.

She is here to follow a high-ranking infant in one of the troops.

A year ago, Sue filmed the alpha female's newborn son, Jazir, on his first day.

-This is pretty unreal, actually.

I get treated with a new baby boy who's just a few hours old.

-Now at 12 months, Jazir is triple his birth weight, around 3 1/2 pounds.

-I really didn't expect him to be so different.

He really does look quite a lot bigger.

He looks really healthy.

-Jazir has grown faster than other babies in the troop thanks to his mother.

As alpha female, she eats better than the other mothers and can provide the richest milk.

Sue is working with Dr. Wolfgang Dittus from the Smithsonian Institute.

For almost half a century, he has studied how rank affects success in toque macaques.

-So being the son of an alpha female has, you know, been really good for him up until now, but the future is still uncertain?

-He's done well, thanks to his mom, to get this far.

Now it's going to be progressively more his own ability to find food, his fighting ability, getting others to help him and helping others.

All those political skills have yet to be learned by Jazir.

-Sue is already witnessing Jazir moving away from his mother and feeding by himself.

-This is great, Jazir foraging on his own on bugs and berries and all those insects, and that is a really important step.

-He is also learning to use his bigger size to out-muscle his smaller, lower-ranking peers.

It gives him time to learn which food is best and where to find it.

Other frustrated infants must wait their turn as Jazir crams extra into his cheek pouches for later.

[ Chittering ] In macaque troops, frustration can build into tension, and tension can easily boil over into fights.

[ Chittering ] -They've got some nasty canines, and they are only for inflicting pain and not to help with eating.

-Badly wounded males can drop down the pecking order, or even die.

It's important Jazir watches older males to learn how to read these potentially dangerous encounters to avoid getting hurt.

Exaggerated brow movements are used to encourage friendly contact.

But tree shaking by the alpha male tells others they need to keep their distance.

-That's really interesting.

That is a definite moment I've not seen before.

Jazir jumping up and down on a branch like a lot of the dominate males do, that's a sign of power and showing your authority, and it's certainly good to see him going through those motions 'cause it's something that he'll be using in the years to come.

-Jazir is practicing skills that could enforce his strength and power amongst his peers.

But he still needs to learn the final and most difficult key to future success -- diplomacy.

[ Chittering ] -He's got a long way to go yet.

He really does need to become socially independent of his mother, meaning that he needs to form alliances with all the males, especially.

-Like all males, Jazir must leave his family in just a few years time to find mates in another troop.

A third of young males don't survive this dangerous transition.

But by working with other males about to leave their troops, Jazir can improve his chances of joining and thriving within a new group.

-What I really want to see is him forging those new relationships and allies with other members of the troop, because in a few years when he leaves, those relationships are going to be vital for his survival.

-As Sue continues to follow Jazir, a change is taking place.

He's starting to develop a softer side to his character.

-It feels like when he's with his peers and others the same age, or even, like, the slightly older males, there's a bit of a different vibe.

-Jazir has joined a huddle and is grooming an older male.

This is the way male macaques nurture new friendships.

Building close ties now means he is more likely to have their support later when it really counts.

-This is great.

This is really what I was hoping to see.

This intimacy between Jazir and the other male macaques is real proof that he's building those essential bonds.

That's a huge step forward.

-The chances of becoming an alpha male are slim, but the skills Jazir is mastering now will give him the best shot at ruling his own troop within Polonnaruwa's ancient kingdom.

Some animal babies are born with an ally who can help them through this dangerous first year.

The vast Mara-Serengeti ecosystem.

It's late August, and the great migration has arrived, 1 1/2 million Wildebeest.

This is peak hunting time for Africa's most successful land predator -- the spotted hyena.

Spotted hyena clans are ruled by the larger, more aggressive adult females with a queen at the top.

In this clan of 60, the second adult in command is Soup.

Bisque and Chowder are her twin daughters.

They are now 11 months old.

Since birth, the sisters could rely on the protection of their mother and the safety of the den.

Now heading toward the end of their first year, they've grown to 55 pounds, almost half adult size.

At this stage in their development, they must learn the skills to survive out on the savanna, where they must explore beyond the den without their mother.

Vianet has filmed throughout the spotted hyena's vast geographic range.

He is tracking the cubs during this critical time as they learn to identify opportunity from danger.

-God, they've grown up really big.

Let me see.

Different to what I left 4 months ago.

-Vianet is working with Michigan State University scientists.

They've studied hyenas here for over 30 years and know what dangers the sisters will face.

-Lions are definitely the main threat to Hyenas.

They're competitors.

They're all going after the same prey together.

Here, lions will actually scavenge from hyenas slightly more often than hyenas will scavenge from lions, and also because they are competitors, they find cubs, find hyena cubs, they will kill hyena cubs.

-Bisque and Chowder must learn to spot and avoid lions if they are to make it through.

In the morning, there is no sign of the sisters at the den.

They have started to explore on their own.

The clan's territory stretches over 7,000 acres, and it takes Vianet hours to find them.

Bisque and Chowder's highly tuned senses are vital to surviving this new world.

Sight will be their primary tool when hunting.

Scent is vital in identifying whether they have strayed into a rival clan's territory, and they can hear hyena calls from 3 miles away enabling them to hone in on kills.

-I think I've heard a call up there.

-Hyenas may call in others to protect a carcass from rival clans or lions.

But as an adult can consume 30 pounds of meat at a single sitting, Bisque and Chowder may not find much left.

Another cub in the clan has found scraps from a kill... ...and Bisque moves in to make a challenge.

[ Cub whines ] [ Bisque growls ] [ Bisque snarls ] Chowder joins the fight, so now both the sisters can chase off others to keep hold of their meal.

-This is the first time I've seen this, trying to crunch food, the bone.

They're becoming carnivore, for sure.

-Adult hyenas have reinforced, oversized teeth and a crushing bite to pulverize bones.

The sisters need 4 years to develop this phenomenal weaponry and must practice at every opportunity.

But feeding alone, they are at their most vulnerable to attack.

-They're so young, they're not quite clear yet what danger is out there.

-They can't see what Vianet can.

-Just by this tree here... [ Low growling ] ...there's a big male lion.

-With their heads down, focused only on feeding, Bisque and Chowder are vulnerable.

-Might be trouble here.

Oh.

Oh.

[ Low growling continues ] [ Lion roars ] [ Bisque and Chowder whine ] Right at the moment when the lion was approaching, my heart was just pounding, thinking, "It might come close and just maybe kill one of those cubs."

This is what they are exposed to.

-It is a threat they will have to learn to live with day by day.

But in their first year, the twins have grown faster and bigger than all the other cubs in the clan.

If they continue to look out for each other, then the signs are they will thrive here in the Maasai Mara.

[ Sea birds calling ] [ Surf rolling ] On California's rugged coast, another animal baby must overcome the challenges of the busy human world.

Monterey, south of San Francisco, is one of the U.S.'s top fishing ports and lands 10,000 tons of seafood from the Pacific Ocean every year.

Seafood is also in demand from southern sea otters living along this stretch of coastline.

Once hunted to the edge of extinction, they now number just over 3,000.

Sea otters are one of the few animals to master tool use, smashing open mollusks and shellfish on rocks they bring to the surface.

It's a complex lesson for any pup to master, but to survive, they have to crack it.

It's April, and Colin, who has been fascinated by otters since childhood, is in Monterey following Limpet, a 5-month-old pup who is fast getting close to independence and will have to master tool use soon because he'll have to leave his mother in a matter of weeks.

-He has grown a lot!

He's certainly looking much bigger and bolder.

-Limpet now weighs 24 pounds, five times his birth weight.

Newborn sea otters can't dive or swim.

For his first few weeks, Limpet either floated on the surface or was towed around on his mother building an intense one-to-one bond.

Now he is 5 months old.

He has reached a precarious stage when his mother could send him away underprepared.

He still likes to feed on her milk, but now she is rolling to discourage him.

If she finds him too demanding, she could enforce weaning and abandon him sooner rather than later.

-They always live on the edge, and that's the thing about sea otters around here.

-Michelle Staedler of Monterey Bay Aquarium has studied the otters here for 30 years and understands the intense pressure the mothers are under.

-They're still lactating.

That takes a lot of energy, and then they're also giving the pup a third of the prey items or the food items that they bring up from the bottom.

So they're constantly giving, giving to the pup, and they get skinnier and skinnier as time goes on, so it's a big draw on their energy resources.

-But his next meal comes from Mom again, a large, burrowing marine worm she dug up in the seabed.

-Yeah, every time she brings something up, he's going and grabbing it from her.

He should now be hunting by himself.

-But there might be some hope.

April is squid season.

Millions of opalescent squid come to spawn on this seabed here, a massive seasonal boost for the otters and also for fishing fleets, who work 24 hours a day.

This should be easy prey for Limpet to practice on.

-Oh!

Oh.

Ah, look!

-Finally, Limpet lands a catch.

-That really proves he's getting someplace.

-Squid spawning only lasts 2 weeks.

These easy pickings will soon vanish.

To really succeed, Limpet must learn how to find and open shellfish, a complex procedure that his mother seemingly performs with ease.

-He's been watching his mom over the months, watching her manipulate all those shellfish, and that's what I want to see him do.

I want to see him dive down to get something, bring it up, and actually open it up and eat it because that would really meant that he's ready.

-To master tool use, a pup first needs to identify a tool.

Sea otters scour the seabed for a suitable stone or anvil, which they store in a pocket of skin under their arm.

Then, once they find a mollusk to open, they bring both to the surface, rest the rock on their belly and begin bashing.

It takes a great deal of manipulation, coordination, force and energy to get to the protein rich and fatty contents, something Limpet has to get to grips with in the next few days to prevent his mother leaving him too soon.

But after a couple of days, Limpet surfaces with a stone, a tool.

-That's great.

Wonderful.

-All he needs is something to work on.

-He's got it!

-A mussel.

[ Stone clacking ] -Good job.

Success.

Look, he's got it open.

That's a really important thing to see.

Fantastic.

And he's not just, you know, copying his mom anymore.

He's not just sort of going through the motions.

He's actually making his own decisions, so he really has nailed it.

-Limpet has reached a fundamental milestone for a sea otter pup -- tool use.

Not only has he unlocked access to a whole host of prey items in the marine environment, but by taking some of the pressure to find food off his mother, he has bought himself valuable time with her.

He will have a few more weeks in her care and protection to practice essential life skills before he embarks on life without her.

Then he'll join other newly weaned pups to start a new adventure on the coast of California.

The bonds between some babies and their mothers will last an entire lifetime.

It's October in Samburu, the end of the dry season.

After 5 months of baking heat, all life here is desperate for the rains.

African elephant Cyclone is the one-tusked matriarch of this herd of three mothers and their young.

Safina is her daughter.

She is 1 year old, and this is her first dry season.

During drought, mothers can struggle to provide enough milk.

To survive during these dry times, Safina must learn to tackle seasonal foods herself.

Wildlife cameraman Bob Poole has spent decades filming elephants, which has given him a unique affinity to and understanding of them.

-It's peak of the dry season, and food and water are really hard to find.

Safina is almost 1 year old now.

I really want to know what she's learning, and one of the things I'll be looking for is how she's using her trunk.

-No other animal has a body part so specialized and versatile.

As a newborn, Safina had very little control of her trunk but was able to use it to express bonds of friendship.

-[ Lowered voice ] I've got a great shot going now with Safina standing next to Cyclone, her mother.

Remarkable how -- how big she's become in 1 year.

[ Cyclone rumbles ] [ Bird squawks ] -Without the rains, the nutritious grasses elephants prefer have withered and died.

The herd can only get enough food by feeding on woody shrubs, like acacia, but stripping bark and leaves whilst avoiding 2-inch-long thorns requires trunk strength and dexterity... something Safina hasn't quite grasped yet.

-[ Laughs ] [ Laughs ] -Unbelievable.

That is so cute.

[ Safina trumpets ] -For now, Safina returns to Cyclone to suckle.

In her first year, her milk intake has doubled, and she's tripled in size.

But to keep growing and developing, it is vital for Safina to learn from the adults how to feed on these plants.

[ Elephant rumbles ] [ Elephant trumpets ] And at this age, Safina is capable of learning new behaviors rapidly.

Ears spreading and charging towards an unsuspecting victim... [ Safina grunts ] [ Bird squawks ] ...makes her look bigger and more aggressive.

-[ Laughs ] You can see her chasing the bird there.

Look, here she comes again.

[ Safina trumpets ] [ Laughs ] Isn't that hilarious?

[ Laughs ] They're so fun.

-But Safina must keep up as the herd are almost constantly on the move.

[ Bird squawks ] [ Elephant rumbles ] Each adult must search for up to 200 pounds of food a day, but they also need up to 20 gallons of water.

Now at the end of the dry season, the only source left for all the elephants in Samburu is what remains of the Ewaso Ng'iro River.

Elephants don't drink through their trunks like a straw.

They draw water partway up their trunks and then spray it back into their mouths, up to 2 gallons at a time.

-What I'm waiting to see is her actually get water in her trunk and lift it up into her mouth the way they do as they get older.

And there it is right now.

I just saw it.

She's got water in her trunk and she's lifting it up.

Most of it is spilling out, as you would expect from a baby trying to learn to use a cup or something.

Anyway, practice makes perfect.

-Every day, Bob looks for signs that Safina is developing the trunk control to finally feed herself during this arid time.

Learning can be a slow process... ...but months of watching her mother are starting to pay off.

-[ Whispering ] Look at the way she's using her trunk now.

You can see she's really starting to master it.

-But Safina will really be put to the test when she takes on the thorny acacia that the adults are eating.

-That's what we want to see.

-Safina is showing the trunk strength and dexterity needed to get past the acacia's defenses.

-Exactly copying her mother, mimicking the behavior of taking the shrub and eating it.

[ Cyclone rumbling ] -Being able to feed herself during the hardest of times is a vital step forward in Safina's development.

-I've seen how Safina has been able to manage her way through this first year thanks to her mother, who is so intelligent, and she's teaching Safina now all these things.

Granted, Safina is only 1 year old now, but next year she'll know more, and the year after that she'll know even more, and in 60 years or so, perhaps she'll be a great matriarch with a herd of her own, a giant family.

I hope so.

[ Safina rumbles ] -Within just a year, these animal babies have transformed... ...from vulnerable newborns into confident characters.

[ Safina trumpets ] As they've grown, they have faced a variety of challenges... [ Lion growling ] ...overcoming their fiercest rivals, escaping from potential disaster and learning the skills to survive in their environment.

They have beaten the odds and adapted to this ever-changing world.

They are now ready to take their next steps into the wild at the end of their first year on Earth.

-To order "Animal Babies: First Year on Earth" on DVD, visit ShopPBS or call 1-800-PLAY-PBS.

This program is also available on Amazon Prime Video.