NARRATOR:
In a place called Hell Valley,
an ancient tribe relies on each
other to survive.
A monkey's position in the group
is inherited from its mother.
Bloodline determines rank,
and every member
knows their place.
But in this world of tradition,
there are opportunities
to change
your fate.
One quiet moment
can have great significance,
when a young monkey
bonds with the leader of
the troop.
In this clan,
nothing goes unnoticed --
it's all part of the drama
unfolding deep in
the Japanese Alps.
NEESON: Long ago, one hearty
tribe made an epic journey...
Traveling thousands of miles,
crossing treacherous
mountain passes
and deep snowbound valleys.
By the time they finally
settled down,
these macaques had traveled
farther North
than any other primate
on Earth --
aside from us.
Over time, they adapted to
the extremes of the seasons
and rightfully earned
their name, "snow monkeys."
To this day,
the descendants
of that ancient tribe still roam
the mountains of central Japan.
And this is where
our story begins.
It's early winter
in the Japanese Alps,
but already
the temperature
is well below freezing.
Here, boiling volcanic waters
feed the Yokoyu River,
keeping it ice-free
all winter long.
Snow monkeys take advantage of
the subterranean heat by
huddling over thermal vents.
Higher up in the trees,
families cling
tightly together.
In the frigid morning air,
no one is quick to rise.
Well, almost no one.
Hiro is just eight months old.
And as he watches
the juveniles play,
he's anxious to start
his day as well.
Hiro and his friends
are determined to get the rest
of the troop on their feet.
No easy task
in a family this size.
The troop is 160 members
in all,
mostly females
and their offspring.
Males usually leave home
before they reach
sexual maturity.
But a handful of adult males
may stick with the troop,
ensuring its safety.
Hiro's mother
is a lower-ranking female,
a status he'll likely share
until he's old enough
to leave the troop
and chart his own path.
His rambunctious play has even
roused the troop's leader.
Kuro-san has a reputation
for being ill-tempered,
with little tolerance
for youngsters.
The clan roosts
high in the mountains,
but every morning they heed
a familiar call.
A whistle from the valley below
beckons them down the mountain.
[Whistle in distance]
Hiro and his cousin
are still busy playing,
while the rest of the family
is already on the move.
And this is why
they're in such a hurry --
grain has been scattered
to supplement the troop's
meager winter diet...
And no one wants to be late
for breakfast.
But someone is missing.
Hiro and his cousin
have lagged behind.
[Hiro calls]
And his cousin
is no help at all.
Just one familiar face
is all it takes,
and they are
back on track.
Keeping up with the troop
is vital.
For snow monkeys,
family is survival.
But there's something else
drawing them down the mountain.
Jigokudani, or Hell Valley,
is famous for its hot springs.
And some 50 years ago,
one was built exclusively for
the Hell Valley troop.
It became
an overnight sensation,
and snow monkeys
have been soaking up
the warm volcanic waters
ever since.
It's a communal affair,
open to all
regardless of rank.
Every member of the troop
is a unique individual...
some a little more unique
than others.
Take Bubbles, for example.
She loves making bubbles
on the water's surface...
and seems completely
engrossed in the task.
And there's Shiro-san.
He's a lover of the hot spring,
even earning the nickname,
Hot Springs Uncle.
He's supposed to be Kuro-san's
right-hand man
when trouble breaks out...
But he spends most of his days
lounging with the ladies.
Kuro-san rarely enters
the hot spring.
Instead, he spends
his days alone.
He's still new to
the job of troop leader,
and perhaps
the added stress
has made him more withdrawn
than normal.
But that doesn't stop Hiro.
Maybe it's the bitter cold,
or maybe he thinks Kuro-san
needs a little company.
Kuro-san ignores
Hiro's gesture.
He'd rather be alone.
Yet it seems
no matter where he goes, he is
surrounded by little ones.
As evening approaches,
the troop
must seek shelter
deeper in the forest.
But Kuro-san
seems reluctant to lead.
Maybe, it's all
too much for him.
The late day flurries
are a reminder --
the worst of winter
is yet to come.
A fresh bed of snow
fills the forest floor
and the troop takes to the trees
to avoid the deep drifts.
On a steep hillside,
a g*ng of juveniles
is playing
"king of the mountain."
Play-fighting is how
young monkeys
test each other's
strengths and weaknesses,
sorting out a delicate
balance of power.
This is not a battle yet,
but a dance.
One young g*ng leader
decides to turn this into
a more serious contest.
The juveniles caught downhill
feel threatened by
his aggression...
and call for reinforcements.
[Calling]
But their brother
at the top of the hill
is unaware the game
has changed.
The belligerent youngster
tries to assert his dominance,
but the lower hill g*ng
refuses to back down.
Now, as back-up arrives,
the troublemaker realizes
he may have
overplayed his hand.
With all forces
converging on him,
his only option
is to flee.
Finally, he wriggles free
and makes a dash for safety.
But the point of this battle
has already been made.
This little g*ng of juveniles
has a new leader --
at least for now.
In a family
more than 100 strong,
learning to play with others
is the most important thing.
Hiro's made a snowball
and tries to get his cousin
to play along.
The relationships he forges
through this simple act
may one day tip the scales
in a more serious game.
But for Hiro,
being playful
comes as naturally
as the newly-fallen snow.
It's getting late,
and the snow is growing thicker
by the minute.
Suddenly, Hiro's game
is cut short.
There is a sense of urgency
in the air.
A storm is coming.
The troop must seek shelter
for the night, and this time,
Kuro-san leads the way.
But as they climb,
Hiro falls farther
and farther behind.
His mother scans the area
for her son
as the others move on.
[Hiro cries]
Hiro's desperate calls
are swallowed up by the wind.
His mother continues
her search,
but fast-moving snow
has erased his tracks.
[Hiro crying]
[Hiro crying]
Finally, his mother hears
his faint cries.
Now, Hiro holds on tight.
He was lucky this time --
second chances don't come along
often in Hell Valley.
Storms like this
can last for days.
During winter, more snow falls
on the Japanese Alps
than almost anywhere else
on Earth.
Snow monkeys have learned to
keep friends and family close.
It is truly
a matter of survival.
Without the warmth
and companionship of others,
the bitter cold
sinks into their bones.
The troop is drawn
down the mountain,
knowing the hot spring
awaits them.
One by one, families gather
in the water to soak,
each seeking the warmth
so desperately needed.
Shiro-san was one of
the first to arrive,
but now the little pool
is getting packed.
Kiko is a lower-ranking female,
but a regular to
the hot spring.
In her eagerness to squeeze in,
she's managed to annoy
higher ranking Tomano.
Kiko tries again,
but Tomano won't budge.
Shiro-san is hoping this little
spat doesn't get out of hand.
But finally he steps in
to break up the fight.
As things settle down,
Kiko takes a different tack,
and finds an opening
behind her sister.
Yet, Tomano isn't ready
to leave Kiko alone.
But strangely,
she's not back to fight.
She slides over
and grooms Kiko.
For snow monkeys, grooming is
an act of reconciliation,
a way of making up
after a fight.
In a community that depends upon
one another for survival,
grooming is the glue
that binds the troop together.
It's partly a free meal,
partly good hygiene --
beneficial all around.
In fact, it may be
better to give
than receive --
the very act of grooming
leads to many benefits.
And the more equally
you distribute
this act of kindness,
the calmer and healthier
you become.
Kuro-san, the troop leader,
sits alone.
He huddles with no one
as he shivers in the cold.
But with his
less than sunny disposition,
most of the troop
have given up on him.
The only one who still
seeks him out is Hiro.
So far, Kuro-san doesn't seem to
mind him
hanging around too much.
It's possible that
Hiro's plucky nature
is slowly chipping away at
Kuro-san's icy facade.
For on this quiet,
snowy afternoon,
something is about to happen
that will surprise everyone.
Suddenly,
Kuro-san folds Hiro
into his arms --
though he isn't quite sure
he's made the right move.
Well, at least they are both
a little bit warmer...
and honestly, that's how
some relationships begin.
It's always
sort of a dance, really...
An awkward...
jerky...
odd looking dance.
But eventually,
every pair figures out
the moves.
And then,
they're on their way.
This is all highly unusual.
Seeing any male with a youngster
perched on his back
is odd enough.
But for a reclusive leader
like Kuro-san
it's even more surprising.
And the spectacle isn't lost on
the rest of the troop, either.
Now, as Kuro-san
leads the troop,
Hiro has a first class
ticket --
a chance to see the world
through the eyes of a leader.
Hiro watches
his new mentor intently.
As they shred bark together,
Hiro's confidence grows.
And with his
air of loneliness lifted,
Kuro-san has new energy.
Kuro-san has found a spot to
bask peacefully in the sun...
well, sort of.
With Hiro now at his side,
the days never seem to
slow down much.
But will this fragile
relationship last?
Or melt away
with the winter snow?
It won't be long now --
spring is on its way.
With help from the troop,
the ornaments of winter
are taken down one by one.
The river surges with
the new snow melt.
The warm rains
wash the forest clean
and fill the river
to its banks.
Slivers of spring,
like fiddleheads
and peat moss,
are peeking out,
preparing their takeover.
Snails emerge from hibernation,
stretching out from their shells
to search for
young green shoots.
The troop moves
through the forest
like explorers of a new
and verdant land --
stopping now and again
to soak up the warm air
laden with the intoxicating
scents of spring.
In Japan,
cherry blossoms are the symbol
of the ephemeral nature of life.
The troop takes advantage of
these sweet flowers
while they last.
The forest is a buffet,
and Hiro hardly knows
where to begin.
After eating bark and twigs
all winter, this is paradise.
But an unfamiliar cry
has gotten his attention.
Rina has a brand new baby boy,
just hours old...
And she's not the only one.
The forest has been
turned into a nursery,
with babies everywhere.
Newborn snow monkeys
are small enough
to fit in
the palm of your hand.
But these little
bundles of energy
can't be contained
for long.
For mum,
keeping them safe
is a full-time job.
They're intensely curious,
but are blissfully unaware of
troop politics.
Wandering up to a stranger
can be a dangerous lesson...
unless she's your aunt.
But this constant exploration
is how babies learn
about their world,
so it's a good thing
snow monkeys are
such patient mothers.
Both Rina and her sister
have given birth,
just a week apart.
During the short spring,
the troop will have around
Rina's sister
is an experienced mum,
and her eldest daughter
is always close at hand,
keeping a watchful eye
on her little brother...
especially now
he's beginning to wander.
With mum's busy schedule,
it's always good to have
a little help around.
Every day is a new lesson,
and by sticking close to mum,
all the tiny secrets of
the forest will be revealed --
like how to find
insect larvae
under the bark of
cedar trees.
This time of year a monkey's
diet is mostly greens,
so it's important to
look for protein
wherever they can find it.
It's a bit like rummaging
through the kitchen cabinets --
eventually, you find
what you're looking for.
Like all kids,
they learn by watching others,
and Hiro,
now one year old, is eager to do
everything grown-ups do.
Like most things,
there's a bit of
a learning curve.
Clearly there's a skill
to this peeling business
that Hiro has yet to master.
Maple trees
are a troop favorite,
and Rina's sister is busy
plucking fresh new shoots.
Now four weeks old, the babies
are already learning to climb.
But confidence...
well, that comes
with practice.
[Baby squawking]
There you go,
safe and sound.
On the valley floor,
the troop relaxes
in the sunshine.
[Squawking]
But a cry of distress
is upsetting
the calm of the forest.
It's a brand new baby --
with no mother in sight.
Rina forages with her young baby
clutched to her,
just steps from the infant.
Uncertain what to do,
Rina minds the first rule
of snow monkey motherhood --
look, but don't touch.
But clearly
something is wrong here,
and she can't ignore
the desperate baby
in front of her.
The new infant
is still a bit shaken,
but is slowly realizing
she is no longer in danger.
Rina, on the other hand,
may not appreciate
what she's taken on.
Having two mouths to feed
is quite a challenge.
The new baby can't see much
beyond her reach just yet,
but somehow she seems to know
she's found a new mum.
[Thunder rolling]
Summer rains come early
to Hell Valley.
For the babies,
the downpour is something
entirely new.
While Rina nurses
her adopted baby,
her son is busy exploring
with a new playmate.
And Bubbles is transfixed
as rain creates magic
on the water's surface.
Kuro-san's unusual relationship
with Hiro continues to blossom.
While all around them,
Japanese Wisteria
is in full bloom.
As Kuro-san gently grooms
his little buddy,
the juveniles...
well, they're up to
their usual antics.
In a sly move,
they have commandeered
the hot spring.
Instead of the heated waters
of winter,
cool river water is now
piped into the pool.
It's the perfect
summer swimming hole.
Maybe it's just the weather,
or maybe it's
Hiro's influence...
Whatever the case,
Kuro-san seems
more relaxed than ever.
But while the juveniles
are playing,
the mothers
have their hands full.
For Rina,
the job is
twice as hard.
With each passing day,
nursing and carrying
two infants
is becoming
more of a burden.
She can barely manage to
keep up with her sister.
While her son is growing
stronger every day,
her adopted baby remains weak,
struggling just to
keep a grip on mum.
As the days pass,
it becomes clear that there is
something very wrong
with Rina's
adopted daughter.
It's possible Rina could not
produce enough milk
to feed both infants,
or maybe the adopted baby
was already ill.
There is nothing
Rina can do now.
Rina's son has yet to realize
his adopted sister is gone.
Summer gives way to autumn.
[Animals calling]
Once again,
Hell Valley is transformed.
But it's not just the color of
the leaves that has changed.
The usually quiet,
reserved Kuro-san
is now loud
and aggressive.
Hiro takes refuge
with his mother.
Kuro-san's face is flush,
his body taut, his eyes wild.
This is not
the affectionate leader
that gently groomed him
in the summer sun.
It's mating season
in Hell Valley,
and Kuro-san has only one thing
on his mind.
But he's got competition.
Males from outside the troop
have come to Hell Valley
to mate,
and they're making their
presence known.
Kuro-san keeps a close eye
on the intruders,
but each day,
they edge a little closer.
Autumn days are short
in Hell Valley,
and bulking up for winter
is the going concern.
Some strip bracket fungi
from the trees,
while others dig up the last of
the season's chestnuts.
As the troop is busy foraging,
one of the outside males
silently slips past Kuro-san.
He's tracking down a female
crossing the valley.
When she tries to run,
he gets aggressive.
He tries to separate
her baby from her,
but she rushes in
to protect it
as the baby makes a dash
for safety.
Her eldest daughter
tries to help,
but she is pushed aside
by the large male.
Kuro-san and the other males
rush in,
and the intruder makes
a run for it.
But Kuro-san and Shiro-san
are hot on his tail.
They pin him down
at the river's edge,
but the intruder breaks free
and uses the river
as a shield.
With the icy river between them,
the male scales the steep cliff
to make his escape.
His scar will be
a permanent reminder
of the troop's strength.
His comrade watches
from the cliff above.
If he wants to mate,
he'll need
a different approach.
Kuro-san now turns
towards Hiro's mum,
grooming her affectionately.
Hiro wants to nurse,
but for once,
it's her turn to be pampered.
Mating is a dance,
and the females often lead.
One of the outside males
has made an impression
on Hiro's aunt.
She's chosen a secluded
patch of forest
for a romantic rendezvous.
The cries are mating calls.
Attraction is a difficult thing
to define,
but her interest in
this exotic foreigner
does makes genetic sense.
He represents fresh genes
from outside of
Hell Valley.
By breeding with this male,
she will ensure that her own
troop will stay strong.
Wind sweeps across
the mountains,
taking with it
autumn's colors.
Soon, the valley will be under
a blanket of snow.
With autumn behind them,
the troop settles in to their
winter routine...
a diet of twigs
and bark.
Hiro nibbles on
the buds of a maple.
Not far away,
Kuro-san is doing the same.
Even after the trials of autumn,
it's clear their relationship
hasn't skipped a beat.
In fact, it seems
stronger than ever.
The troop moves across
the valley,
each member keeping
close tabs on
their mothers and sisters,
ensuring no one is
left behind.
And like family,
Hiro and Kuro-san stick close
as they brave
the winter together.
Their unusual relationship
may have started
out of convenience --
Each seeking comfort
that first hard winter --
but it has grown into
something more...
A friendship
that has lasted through
the seasons.
By the following spring,
Kuro-san has grown into
a confident and caring leader.
And Hiro is always
by his side.
He's already two years old
and even has
a brand new baby sister.
Like every spring,
there's new life in the troop.
Last year's babies
are now the curious
one-year-olds
Hiro once was.
Hiro may have come from
humble beginnings,
but this bright-eyed youngster
has lit a spark in
a once lonely leader.
Their unlikely friendship
has already begun to reshape
their future.
To learn more about what you've seen on this "Nature" program,
visit pbs.org.
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