From the mighty grizzly bear...
..to the endearing, real-life Paddington, the spectacled bear...
..and the majestic polar bear, king of the frozen North...
..this remarkable animal family has long captured our imagination.
But as some of the biggest animals on Earth, they need
more than just the bare necessities to get by.
So, whether it's raiding nature's larder,
standing up to their rivals...
..raising the cubs...
..or even proving that you're smarter than the average bear...
..each must draw on all its skills to survive.
Today, bears face their biggest obstacles yet...
..as they try to get to grips with a changing world.
But whatever they're confronted with,
bears always try and take life in their stride.
Bears are some of the most charismatic animals
to walk our planet...
..and they all share the same key characteristics.
Like this brown bear, their impressive size
and strength sets them apart.
They have forward-facing eyes with vision similar to our own.
But their sense of smell is over 100 times more powerful.
Large, dexterous paws are tipped with long claws
that can open up even more opportunities.
Although they're classed as carnivores, most bears eat
a diverse mix of plants, insects and meat.
Across the world, there are just eight species,
yet they range over a wide variety of habitats...
..from the ice world of the North,
through the mountains of Asia...
..to the heat of the tropics.
To live in these very different places, they've had to adapt.
The skills they need to survive must be learned and mastered
over a lifetime.
So making it as a bear is far from easy.
Katmai National Park in Alaska -
a wilderness where mountains
meet the sea.
This is home to the brown bear,
sometimes known as the grizzly.
GROWLS
And they're gathering for one of the most extraordinary
events in nature...
..the salmon run.
Every summer, millions of salmon head upstream to spawn.
Waterfalls are a natural barrier for the migrating fish...
..and the bears know it.
Three cubs emerge from the forest.
Their mother is thin and needs to eat.
But this is a dangerous place for a young family.
THEY GROWL
Competition for every fish is fierce.
For their own safety, the cubs are kept on the sidelines.
It's a prime position to watch the action.
Catching a powerful, slippery salmon is tough...
..and the grizzlies, like all bears, must work out the best way to tackle
the food on offer.
There's the dash and grab.
Less energetic is the stand and wait approach.
But it has its downsides.
Beneath the falls, sit and wait is the most successful strategy.
Fights can break out at any moment.
For now, the cubs are out of their depth.
An experienced big male can catch 30 salmon a day...
..and eventually most of them have had enough.
The mother bear decides it's safe to return.
Her cubs are depending on her.
A perfectly timed catch.
Patience and experience pay off...
..and the family can feed.
The skill and judgment needed to master a chaotic situation
like this, with tricky prey and other bears, takes years to learn.
So, for cubs, lessons start early.
The forested areas of North America
are home to the grizzlies' smaller cousin, the American black bear.
These cubs are nearly four months old and, at this age,
they're learning new skills every day.
Play fighting improves their coordination
and builds muscle strength.
It also helps sort out who's who in the pecking order.
The youngest cub soon learns her lowly position.
She may be last in line, but she still benefits
from her mother's milk.
It's almost 25% fat.
That's five times as rich as cow's milk.
THEY GRUNT
Soon, these cubs will move on to solids, so they're starting
to investigate other food around them.
In spring, young leaves and ants are a good source of protein.
But it's too early for pine nuts.
Learning what they can eat and when will be vital in the future.
But right now, the cubs are vulnerable,
and there are more pressing issues.
There are predators in these forests.
A bald eagle could snatch and kill a cub...
..as could a coyote.
Most dangerous of all are grey wolves.
But there is a place the cubs can seek safety.
Thanks to their strong, curved claws...
..these bear cubs can climb from a young age.
But perfecting the technique takes time.
They need to work out which trees are best for gripping onto.
Smaller trees and branches are good for practice -
well, most of the time.
This tree is too flaky.
This tree is too slippy.
But this tree is just right.
Going up is one thing...
..but coming down again can require a helping hand.
THEY GROWL
All bears must learn how to avoid danger...
..and there's one species that's come up with an unusual strategy.
India...
..home to the sloth bear.
Here, there are fewer tall trees to escape into.
And, in any case, the local predators are skilled climbers.
So these sloth bear cubs need a different escape plan.
WAILING
When their mother sounds the alarm,
they head for the safest place around.
Her shaggy coat means the cubs can climb
onto her back, clinging on using strong forelegs and toes.
It's unusual for a big cat to challenge a sloth bear mother...
..unlike her cubs, who so often do.
A mother bear is the cubs' protection and their only guide.
With so many skills to learn,
most bear cubs stay with their mother for two to three years.
THEY GROWL
In Alaska, a five-month-old grizzly bear cub
is working out his boundaries.
Adult bears spend most of their lives alone,
so this time with his mother helps him learn how to interact
with other bears.
All cubs need to master their new surroundings.
In the Arctic,
young polar bears emerge from their den to take their first
steps in the snow.
This cub is more cautious.
They need to get to grips with this terrain quickly.
Soon, they will have to walk many miles in search of food.
In Canada, another grizzly bear cub is trying his luck at fishing.
His mother shows how it's done.
Observational learning is one of the most effective ways for cubs
to pick up new skills, and, with so many salmon here,
he's got a good chance.
Now to hold on to it.
As cubs grow more independent...
..they start trying things out for themselves.
In the woodlands of Minnesota, a fallen tree holds something
that bears are famously fond of...
..honey.
BEES BUZZ
And it hasn't gone unnoticed.
This nine-month-old black bear cub may have never
encountered bees before...
..and sometimes learning can be a painful process.
HE GROWLS
His more experienced mother has a tried and tested technique.
This smash and grab leads to fewer stings.
Honeycomb provides sugars and protein
from the bee larvae inside.
Much of a cub's learning is focused on food. As one of the biggest land
animals, some bears need over 5,000 calories just on an average day.
In many parts of the world,
bears have to adapt and specialise to fuel their sizable appetites.
The Andes Mountains in South America,
home to this continent's only bear.
White facial markings are a clue to its name -
the spectacled bear.
But to many of us, it's far more familiar as the storybook
character of Paddington.
Like its fictional counterpart, this bear has a sweet tooth...
..although in these cloud forests, marmalade sandwiches
aren't an option.
Fortunately, there's another high-calorie food here...
..bromeliads - a family of plants that includes the pineapple.
Growing metres off the ground, they're out of reach
for most large mammals.
Bromeliads are notoriously robust plants, but the spectacled bear
can break them apart with ease.
That's because, relative to its size, it has the largest jaw muscle
of any bear species and grinding teeth that are secured into its jaws
with three roots instead of two.
It's after the sugar-rich core.
The spectacled bear will also eat palm nuts,
birds' eggs and small animals.
But half of its diet is made up of these high-energy plants.
Unfortunately, bromeliads tend to be widely scattered
across this mountainous terrain...
..so these bears have to search
their entire territory to find food...
..which can be up to 115 square miles.
They have a surprising skill to help them.
Research has shown that spectacled bears can remember the location
of important resources by building up a mental map of the area.
Higher up the mountain is the paramo - a land swathed
in tall grasses.
It's too cold for tree-growing bromeliads,
but not too cold for puyas -
giant ground bromeliads that can stand over three metres tall.
But getting to their sugary centre
requires a different technique.
The spectacled bear can satisfy its need for calories
by using its strength and its ability to find
and remember food sources.
But on the other side of the world, a very different habitat presents
an even greater challenge.
Across Asia, many of the forests are populated by one kind
of plant - bamboo.
In China alone, bamboo forests cover
an area of over 20,000 square miles.
But for an animal trying to make it here,
there's just one problem.
Bamboo is incredibly tough and fibrous
and particularly low in calories.
So, to conquer this landscape,
one bear has done something quite extraordinary.
The giant panda has adapted its body
and even its behaviour
to almost exclusively eat bamboo.
The bear spends its days searching the Qinling Mountains for the most
nutritious parts of the plant.
It usually sits down to eat...
..so that its flexible forepaws
are free to help harvest the bamboo.
It's the only bear that has evolved a wrist bone to act as
an opposable thumb...
..allowing it to select and manipulate the most tender
part of the plant.
To prevent injury from bamboo splinters,
its oesophagus and stomach are lined with tough, thick walls.
But its digestive system, like those of other bears, is built
for eating meat, and it lacks the plant-digesting bacteria
of a true herbivore.
So, to get enough nutrients, it has to feed for up to 14 hours
a day and chew its way through 12 kilos or more of bamboo.
This low-energy diet also affects a panda's behaviour.
To avoid exhaustion, it limits unnecessary socialising and walking
in tricky terrain.
Bamboo is evergreen,
so the panda can eat all year round.
It's even come up with a method of breaking ice off frozen leaves
by using its warm snout.
Fossil evidence suggests that pandas have been eating bamboo for the last
four million years, but their complete dependence on one plant
has put them in danger.
Pandas once thrived across eastern and southern China
but, as the forests made way for human development,
their population crashed to just 1,000 bears.
Today, their range is restricted to six isolated mountain ranges.
Over the last six decades, efforts have been made to save the panda
by giving them protection and setting up reserves.
And in the early 1980s, China opened its first
captive breeding centre.
This programme has been very successful, with over 300 pandas
born in captivity.
Some of these are now being released into the wild.
Work to bring this bear back from the brink of extinction
is starting to pay off.
Today, the wild population has nearly doubled
to just over 1,800 pandas.
An almost exclusively vegetarian diet is the exception for bears.
Most need more protein to thrive, and they'll go to extreme lengths
to get it.
In India's dry grasslands, food is hard to come by.
This fortress holds the answer.
But how to get inside?
The sloth bear is the real-life Baloo...
..the character in Rudyard Kipling's Jungle Book.
Its distinctive shaggy coat made early explorers think
it was a sloth, but it's the bear's powerful paws and unusual face
which are key to how it gets its food.
Under cover of darkness, it targets the mound's inhabitants...
..termites.
They build these giant mounds, which are fortified by a wall
of sun-baked clay.
Most termites are less than two centimetres long,
but there could be over a million of them inside.
To get to them, the sloth bear has just the tools for the job.
It uses eight centimetre-long claws to tear into the mound.
Soldier termites have pincers, but they're no match for this bear's
next form of attack.
Long, floppy lips and a lack of front teeth allow it to use
its mouth like a hoover and suck up hundreds of termites at a time.
It can also shut its nostrils to avoid inhaling dirt
or any stray insects.
A sloth bear can demolish an entire termite colony in a single night.
Rich in fat as well as protein,
termites provide almost double the number of calories
as a rump steak.
Insects like these can form 95% of a sloth bear's diet.
Around the world,
physical adaptations allow different bear species to specialise
on the most nutritious food available.
In Southeast Asia,
nothing is out of reach for the sun bear.
Sickle-shaped claws and bare-soled feet
mean it can access fruit in the jungle's tallest trees.
Powerful paws expose insect larvae...
..and they use a 25 centimetre-long tongue to fish them out.
Japan.
On the rocky slopes of the Hida Mountains,
an Asiatic black bear uses its sense of smell and careful
footwork to uncover its prey...
..ants.
It can spend up to eight hours a day flipping these rocks.
When it comes to food, most bears show a remarkable level
of resourcefulness...
..and that's just as well because the bears
living in the Northern Hemisphere
face a particularly difficult challenge.
North America.
In seasonal climates, the food available changes
with the time of year...
..so bears like these grizzlies have to switch food sources
every few weeks.
Spring brings new growth.
Succulent sedges and grasses provide a welcome protein boost.
As summer approaches, seafood appears on the menu, but the bears
need to plan ahead.
They time their hunting during
the 3-5 hour window of low tide.
On the exposed sand,
they detect their prey by smell.
Clams.
Grizzlies can eat as many as 100 clams in one low tide.
They'll also gather seaweed, barnacles and mussels to add
to their varied diet.
But in early autumn,
the bears' appetites
suddenly go into overdrive.
On the coast,
this coincides with the appearance of a major food source.
The salmon are back.
Hormonal changes cause the bears to enter a phase
of excessive eating, or hyperphagia.
They eat almost continuously without ever feeling full.
At this time of year, grizzlies can consume up to 100,000
calories a day.
That's the equivalent of over 1,000 boiled eggs.
But this gluttony has a purpose.
HOWLING
As winter tightens its grip in the North...
..feeding opportunities begin to disappear.
For many large animals, this can spell disaster.
But bears have a solution.
It's all down to an extraordinary feat of physiology.
After their autumn feeding frenzy, they retreat to a den.
Inside, they enter a state of hibernation.
In this deep sleep,
their body temperature drops several degrees
and their heartbeat slows to as few as ten beats a minute.
They don't eat or drink for seven months.
Instead, they rely solely on their fat reserves to stay alive.
Grizzlies, American, and Asiatic black bears all enter this
deep form of hibernation in colder climes.
They don't experience any heart complications, blood clots or
even bone and muscle loss during this extended period of inactivity.
The implications for human medicine are huge.
NASA scientists are hoping the bears' biochemical secrets
will one day help astronauts with long distance space travel.
BIRDSONG
With the arrival of spring, the bears emerge healthy and lean.
After their long fast, they stock up in the meadows.
Bears have had to adapt to make the most of the food available.
But it's not the only challenge they face.
Adult bears lead mostly solitary lives.
And as the season warms up,
many animals have just one thing on their mind.
So, how does a bear find a mate?
The answer involves trees...
..and a good old-fashioned back scratch.
As they rub, they mark the tree with their scent.
It's like leaving a calling card.
The higher they can rub, the better.
This way, their scent can travel further.
And it doesn't take long for these chemical signals
to attract other bears...
..who then leave their own messages.
It's thought that this unusual form of communication helps
individuals work out who's around, who to avoid and who's available.
Now, all they need to do is get together.
On the Alaskan coast, the dating game has moved to the next stage.
Male and female grizzlies gather on the meadows.
Some travel for hundreds of miles to be here.
The big males show off with a strut...
..known as the cowboy walk.
But there's more to this swagger than meets the eye.
As they twist their paws into the grass,
they leave behind a scent trail, made up of 26 volatile chemicals.
The effect is enhanced with urine.
These pungent scents and body postures signal the bear's
intent to mate and help males establish a hierarchy.
But when males are evenly matched,
there's only one way to resolve their differences.
GROWLING AND ROARING
With the battle over, the victor can continue his courtship.
In some parts of the world, finding a mate is even more challenging.
The Arctic.
Freezing temperatures and gale force winds make this land of snow and ice
one of the most inhospitable places on the planet.
But to a polar bear, it's home.
Polar bears evolved from brown bears many thousands of years ago
and spread north.
Here, a lone male occupies
a massive home range,
sometimes in excess of 100,000 square miles.
That's an area over 200 times bigger than Greater London.
So, the chances of meeting a mate here seem vanishingly small.
But this Arctic nomad has a strategy.
In common with grizzlies,
polar bears have sweat glands on the soles of their feet...
..so their footprints are full of information.
All a male has to do is follow them.
But his long distance trek is no guarantee of romance
on the first date.
When he finds her, he's got to impress.
She'll only mate with him if she thinks he's fit and strong.
So she puts him to the test.
His downhill tobogganing lacks style,
but he's keeping up.
The next challenge is a rocky ascent.
The female makes it look easy.
Weighing almost twice as much as her, at close to half a tonne,
size isn't on the male's side.
He needs some encouragement.
And she has a unique way of giving it.
This is one of the few times that polar bears come together as adults.
Courtship can last three weeks.
Then, they'll go their separate ways.
The female will spend the winter months under the snow,
where she'll give birth to her cubs.
And the male will endure the coldest weather that
any bear on the planet must face.
Temperatures will drop as low as minus 40 degrees.
But this extraordinary bear has mastered the art of staying warm.
A double-layered fur coat not only helps to keep out the cold,
but it also keeps the heat in by trapping infrared radiation.
And underneath is a layer of pure blubber, up to 11cm thick,
which provides vital insulation.
But to maintain its ample waistline, a polar bear needs high fat food...
..seals.
And the best place to catch them is on the sea ice.
This is where the seals create breathing holes and dens.
The polar bear's sense of smell,
said to be seven times more powerful than a bloodhound,
can pick up the scent of a seal from over a mile away.
To help it walk across the ice sheet,
large paws act like snow shoes to spread the weight,
while bumps of skin on the footpads
and hairs between the toes provide grip.
It can pinpoint its prey by smell 90cm beneath the ice.
But seals are agile swimmers
and nine out of ten hunts end in failure.
There are successes and to survive,
each bear must catch at least one adult seal every ten to 12 days.
But, today, polar bears are facing a new challenge.
With rising year-round temperatures, their hunting grounds are shrinking.
Enormous masses of ice that were frozen for thousands of years
have broken apart and melted away.
Each year, the Arctic's frozen ocean is becoming smaller and thinner.
Polar bears are being forced to swim ever greater distances
to hunt seals.
With their powers of endurance pushed to the limit,
many will starve or even drown.
If current trends continue,
some scientists predict the summer sea ice in the Arctic could be
gone within half a century and with it,
potentially a third of all polar bears.
In some parts of the Arctic,
polar bears are trying to adapt to this changing world.
Driven by hunger, the normally solitary bears have been
filmed coming together to feed on our leftovers.
It's a desperate and slightly alarming strategy.
In today's world,
people are increasingly encroaching on the wilderness.
This is a problem for all animals.
But the bears' opportunistic nature means many of them
will try to take on this new challenge.
SIREN WAILS
Bears have an in-built curiosity and the largest brains,
relative to body size, of all carnivores.
They've discovered a way in to our world.
LAUGHTER
And cubs follow the lead of their mothers.
With their dextrous paws, they are practically made for breaking
and entering.
Unlike many animals, they'll readily investigate anything new
and quickly work out if it can be useful.
Because of their broad diet, they thrive on our food.
Some scientists believe that the bears' problem-solving abilities
mean they should be ranked with monkeys, in terms of intelligence.
And many of them have worked out that modern life can bring
multiple benefits.
The bear's right next to us!
Where we live in such close proximity,
our relationship with bears can at times be fraught.
Oh, my goodness! Oh, my...! SCREAMS
But there is a place where it's become almost harmonious.
The north east coast of Japan...
..and the salmon are gathering offshore.
Soon, they'll head inland to spawn.
This is the Ussuri brown bear.
They've been coming to these shores
for centuries.
More recently, the autumn bonanza
of salmon has attracted other fishermen.
Both of them are dependent on this food source.
While the bears fish in the shallows,
the fishermen target salmon out at sea.
In the past, people here were more fearful of these animals
and tried to fence them out.
But the bears never became a threat
and now around 200 peacefully share space with the human population.
It's a unique relationship, where both can reap the rewards.
In the modern world, bears and people will
increasingly need to share space and resources like food and water.
And, for bears, working out how to do this starts from a young age.
Serranias del Burro, a mountainous region in Mexico's north east.
It's home to the black bear, which is endangered in this country.
For this family,
the biggest challenge in the heat of summer isn't food...
..it's finding enough to drink.
The underlying limestone rock soaks up the rain,
leaving no permanent streams.
Fortunately, there's another source,
but reaching it requires skill and cunning.
This is an area used for cattle grazing.
The ranchers have set up watering holes by tapping into
underground springs.
The bears can take advantage of this,
but the cattle are desperate for water too.
They're naturally wary of potential predators
and armed with sharp horns
which could easily injury or even kill a bear.
The livestock move off.
The family finally have their chance to drink.
But they're still not alone.
It's a big male...
..and the cubs aren't safe.
Their mother has taught them well.
As the male cools off...
..they have to be patient.
Finally, the coast is clear.
The ranchers here are very tolerant of bears.
They even provide a step up for the cubs.
Weighing up the risks and taking advantage of
new opportunities are vital skills for bear cubs to learn.
All too soon, they will have to take their first steps towards
independence and stand on their own two feet.
After spending their early years in the care of their mother,
young bears face a very different world.
For the first time in their lives...
..they are alone.
To be a bear takes a lot of skill.
From avoiding danger...
..surviving the seasons...
..and learning to tackle whatever food is in front of them...
..and if they can do that,
they'll reap the rewards.
But the bears' biggest challenge yet...
..is today's rapidly changing world.
Six of the eight species of bear are vulnerable to extinction.
There is more pressure than ever on their habitats
and the food they depend on.
They'll need our help and our willingness to share space.
If we give them the chance,
their brains, brawn and ability to adapt...
..will do the rest.