All language subtitles for Inside.the.Enchanted.Forests.S01E02.Seasonal.1080p.DSNP.WEB-DL.DDP5.1.H.264-NTb_track4_[eng]

[narrator] In a realm of
constant change...

Earth's seasonal forests are
the most dynamic of them all.

From armies of
vigilante insects,

to a pilgrimage
from ocean to tree canopy.

The march of the seasons inspire
some to burn bright and brief,

and others to make an epic
journey into the unknown.

This is a world
of boom and bust.

All must dance to the beat
of nature's seasonal drum.

Take a journey

through our planet's
kaleidoscope of forest realms.

From the frozen boreal
in the north...

to the tropical jungles
that hug our equator.

From mountain peaks...

to the ocean depths.

Marvel at the magic...

and drama...

that unfolds, as we reveal...

the Secrets of
the Enchanted forests.

[Enchanting music]

These are the monsoon forests
of Borneo.

Straddling the equator,

spring, summer, autumn
and winter hold no sway here.

But these are seasonal forests
all the same.

One dramatic annual shift

transforms this forest
each year.

It's so powerful

that it has driven a once-social
animal into a life of solitude.

This female orangutan gave birth
just four months ago.

It's her first baby.

But like the rest of
her species,

she's a single mum
with no family

or troop to show her the ropes.

She relies on instinct

and an intricate knowledge
of this forest,

passed down through generations.

Their bond is strong.

She is all things to him:

Provider...

Bridge...

and most importantly,
she is his Teacher.

She has seven years

to teach him everything
he needs to know about surviving

in this monsoon forest -

as he will spend the rest
of his adult life alone.

It's the dry season...

so today's first lesson

is how to find a secret
source of water...

in a tree nook,
20 feet above the ground.

But he'd rather go
in search of food.

Mom has over 400 different types
of fruit in this forest

to introduce him to.

but at this time of year, food
of any kind is hard to find.

This giant male

has spotted one of the last
remaining durian fruits.

From a safe distance, they
hungrily watch the male tuck in.

And the baby learns one of
the most important lessons

of them all.

Orangutans do not share food.

Unlike nearly every other
primate species,

they are solitary creatures.

It wasn't always this way.

Like their ape cousins,

orangutans used to be social.

But after the last ice age,
the forest changed.

Now, with food appearing
seasonally,

it could no longer support
large troops.

In a boom or bust world,
each had to go it alone.

Without a troop for support,

this mother had to become
an expert

in the ways of the forest.

And she knows change is coming.

Knowledge learned
from her own mother,

tells her that once a year,

the Monsoon brings a lifesaving
deluge of rain.

But the force
is unpredictable...

and this year,
the rains are late.

Orangutans have learned
to be patient.

Eventually, the sky
will deliver.

This change to wet season
finally reawakens the forest.

And after a quick demonstration
in umbrella construction...

it's finally time
to teach her son

where to find
the now ripened fruit.

With bellies full, they can
practice making their beds.

Tomorrow will be yet another day
of home-schooling.

By falling in sync
with the powerful monsoon,

they have found a way to survive
the all or nothing nature

of this seasonal forest.

Moving away from the equator,

temperate forests have four
separate seasons to adapt to.

For a forest, every changing
season presents an opportunity.

And spring in the Northern
Hemisphere...

... means babies.

But too much 'new life'
each spring

can pose a supply
and demand problem.

Every now and then,

trees conspire together to act
as nature's most synchronized

form of birth control.

In these woods,

reproduction requires teamwork
between tree and animal.

And it all starts with
a burst of spring blossom.

Pollinated flowers transform
into fruit, nuts and seeds,

providing a feast
for the woodland animals,

who spread them far and wide.

When the balance is tipped,

too many seeds are eaten,
leaving too few to germinate.

The trees must find a way
to take back control.

And they must do it together.

Every few years,
the trees collude

to produce a bumper crop
of fruits or nuts,

known as a 'mast year'.

A seasonal glut
that yields more food

than the animals
could possibly eat...

leaving more seedlings
the chance to take root.

This strategy is not confined
to temperate forests.

Trees across the planet use this
method to gain the upper hand.

Now, the trees have to make sure
this new bounty of food

does not encourage
a corresponding baby boom

in the forest animals
the following year,

that will still go on
to eat it all!

So they cunningly follow their
generous 'mast' years

with several 'meagre' ones.

The shift from abundance
to scarcity

curbs any plans
for legions of offspring

and more mouths to feed.

And balance is once again
restored.

It's a master plan.

It leaves the animals guessing,
keeps populations in check,

and most importantly, it shows
who really holds the power.

Across hundreds of kilometres,

trees can precisely synchronize
their 'mast years',

so the overabundance happens
all at the same time.

How they do this is still one of
the forest's greatest mysteries.

[narrator] As each season
ripples through the forest,

orchestrating events
like a musical conductor...

one of the forest's
tiniest residents

is looking for a stage

to put on the performance
of a lifetime.

For this firefly,
late spring brings about

the most important night
of her life.

She's just emerged
from her underground lair

and is still getting used to
her new adult beetle body.

She's looking for love...

...and tonight is her chance
to shine.

But this isn't a solo show.

If she has timed it right,

she'll emerge with thousands
of other fireflies.

She is looking positively
radiant.

Her abdomen contains
bioluminescent chemicals,

that, once mixed, she ignites
by pumping in oxygen.

She then regulates this reaction

to turn her glow...
into a pulse.

Winged males reveal themselves
with their own dazzling display.

She's looking for
the brightest light,

indicating a strong,
virile male.

Bingo.

She adjusts her rhythm...

mimicking his flashes.

[Enchanting music]

Eventually, the pair are
completely in sync.

She's won him over.

When her twilight tryst
is over,

in the cold light of day,

her 'choice' is
a little underwhelming.

Much smaller than she,

the male fireflies are far less
glamorous than the females.

Dating in the dark
definitely works in his favor!

In any case, a fireflies'
'relationship' is short lived.

Their entire lives are geared
towards this seasonal light show

and he will die soon.

She'll carry on to lay
her now fertilized eggs

and then she too will
turn off her light forever.

Destiny fulfilled.

[Mysterious music]

For many, these glittering
courtship displays

are a prelude to a new,
radiant summer.

This change in season

can trigger an influx
of picky visitors.

When seasonal extremes
only allow

small patches of forest
to thrive,

some animals could find
themselves living tooth by jowl

with a monstrous neighbor.

In Colombia, a vast savannah

stretches for over
200,000 square miles.

Despite the extreme shifts

between the wet and dry
seasons here,

trees have found a way
to survive.

[Thunder clapping]

When the rains come,
the rivers overflow...

bringing long awaited water
and nutrients

to the green ribbons of forests
that line their banks.

These unique 'gallery forests'

are the only strips of trees
for hundreds of miles.

They are crucial for thousands
of migratory birds,

visiting each year to this
one spot of prime real estate.

But the birds are fussy.

Everyone wants waterside views,

stable foundations,

and a source of sturdy branches
for nest building.

The higher the spot, the better.

This male great egret
didn't bag the penthouse.

Not to worry.

He's looking particularly
fabulous this year

and hoping his plumage
impresses the incoming females.

[Fanciful music]

This potential mate
shows an interest,

but she wants to check out
his nest before committing.

It's first rate -

close enough to water
to take advantage

of the early summer blooms
of plant and fish life.

But also hidden away in the
branches, for a little privacy.

She approves.

A month later,

the entire woodland is a
frenzy of demanding chicks...

[Baby egrets squawking]

and frantic parents.

But as the egret chicks
begin to fledge,

this perfect location might
not be so perfect after all.

Beneath them...
a monster is stirring.

[Ominous music]

[narrator] The
arrival of the rains

has awoken this caiman
from her state of torpor.

With the forest floor
now a watery highway,

she has easy access
to the nesting areas.

Weak from a season
of not eating...

ideally her next meal would
simply fall from the sky.

[Dramatic music]

For some, the dream riverside
home...

has turned into a nightmare.

[Egrets chirping]

For the lucky ones,

life continues
if they keep to the trees.

The forest wouldn't exist here,

if it weren't for nature's
seasonal balancing act.

The narrow bands of forests
bring with them

opportunity for everyone,
however, ruthless it may seem.

Any tree weakened by the heat
can be vulnerable to attack...

by caterpillars...

beetles...

and aphids.

But in this orchard,
a winged army of protectors

are ready to keep any
potential assailants at bay.

These hornets rule over all
other insects in this forest.

Serving like pest control
officers,

keeping every other bug
population under control.

Their headquarters are located
inside this hollowed out tree.

The hornets have spent the
summer expanding their command.

Hundreds of new offspring
requires a bigger nursery.

The workers recycle
the dead wood from the forest

to construct the new paper-thin
walls of their nest.

Their queen single handedly gave
birth to this entire colony.

Her sole duty now is to deposit
new eggs into each empty cell,

spawning the next generation
of pest controllers.

Hornets are voracious hunters

and they target the food
that is most abundant.

Summer swarms of insects
tormenting the trees

will be exterminated.

[Hornets buzzing]

Powerful jaws
dismember their prize.

Ironically for a hunter,

due to their extreme
hourglass shape,

an adult hornet
cannot digest its prey.

But the plump larvae can.

So the workers deliver the food
to their immature grubs.

Their reward is a liquefied
meat smoothie,

regurgitated back
into their mouths.

[narrator] By summer's end, the
colony has reached its peak.

The ageing queen has given the
gift of 1500 eggs to her colony.

Now, she prepares to pass
her crown to a new ruler.

Her final act of service

is to produce next year's
batch of queens...

... before her body is returned
to the forest.

As the days cool, the summer
bounty of food is ending,

and the hornet empire
starts to crumble.

Now redundant,

even the workers can sense
their time is coming to an end.

The colony's only hope now rests
with their future queens.

These princesses must
build up their reserves

to see them through the winter.

So the last remaining larvae
are sucked dry.

A sacrifice
to the future queens.

The new queen leaves the ruins
of the past empire behind,

never to return.

Next year,
she'll start her own colony

and raise an army
to keep her forest safe.

But her own fate is inevitably
sealed, and one day,

she too will fall
with the autumn leaves.

In one forest,

a seasonal pilgrimage leads
millions of fish from the ocean,

up into the canopy.

And how they got there
is a story like no other...

A true miracle of nature.

It's late summer in Alaska.

As the days grow shorter,

the trees here are preparing
for winter.

They have slowed their growth
and now plough all their energy

into building their winter
stores.

So they need
all the food and water

they can get their roots on.

In this forest, nutrients
tend to wash downriver.

So nature had to find a solution
to bring them back up stream.

And it originates

far, far away from North
America's seasonal forests,

deep in the North Pacific...

These salmon have been spurred

to make the journey
of a lifetime.

The changing season
is pulling them

from their bountiful
ocean home,

towards the land and the exact
river where they were born,

years before.

Their instinct drives them
thousands of miles upriver.

Using the earth's magnetic field
like a compass

to help navigate their way.

But the sheer effort of fighting
against the freshwater flow

takes its toll.

Humpbacked and disfigured,

these males barely resemble
the sleek silver bullets

from their ocean life.

The fish carry valuable
ocean nutrients with them,

essential for the growth
of the trees.

But for the forest to access
those nutrients, it needs help.

For Alaska's brown bears,

the annual arrival of the salmon

marks the start of their
'fishing' season.

[Exhilarating music]

During these high times,

the bears need only eat the most
nutritious parts of the fish,

fat-rich brains,

skin,

and eggs.

The rest of the carcass
is tossed aside.

Leaving plenty for others
to take advantage of...

... including the forest.

[narrator] Here, the bears
leave tons of leftover fish to

decompose, releasing rich
nitrogen into the soil.

A key nutrient for the trees,

helping them grow three times
faster than elsewhere,

making them stronger,

and more nutritious

for all that consume them.

And when the bears
have digested the fish,

they further feed the forest
with rich droppings and urine.

Bears fish all along
these migration rivers,

feeding the forest as they go.

For the salmon that make it
past the bear gauntlet,

they break off
to spawn in the shallows.

[Enchanting music]

It's their final act.

They put every
ounce of energy they had

into battling their way here,

for the chance to reproduce
just once.

But their effort ensures
a new generation of salmon

will continue the cycle,

providing a vital supply
of nutrients to these forests.

Everything that lives here

benefits from the tireless
efforts

of a very determined fish,

and an arduous
1800 mile journey,

bringing nourishment
to an entire forest

from ocean to canopy.

Throughout the seasons,

much of the forests of
Alaska remain evergreen.

But as summer draws to a close
in temperate forests

around the world,

each tree must make a critical
decision about its future.

The sun is losing its power
and the drop in temperature

triggers a beautiful
transformation.

The trees of a forest
often work in synchronicity,

but this time, it's different.

As the daylight hours decrease,

the sun no longer provides
enough energy

for the leaves
to turn it into food.

Soon, a tipping point is reached

when holding onto their leaves

becomes more of a burden
than a benefit.

Each makes its own judgement
on when to shed.

It's now recognized
that trees have 'memories'

and call on their previous
experience

to make this crucial decision.

In fact, a more 'anxious' tree

may drop early based on
past traumatic incidents.

No-one wants to get it wrong.

Too early and you lose
the chance

to make the optimum amount
of food for the winter.

Too late and the frost
might damage the tree.

Any remnants of water in
the leaves could cause them

to rupture
like a burst frozen pipe.

When the decision is made,
the green chlorophyll pigments

used to harvest the sun's energy
are broken down...

revealing a blaze of gold...

and red.

[Enchanting music]

The tree,
its crown now stripped bare,

is ready to sleep.

Protective buds appear

where the leaves once
connected to the stems.

They contain a chemical
that places the tree

into a state of silent slumber,

before the cold really sets in.

[narrator] As autumn
creeps into winter,

the once buzzing forest
takes on an eerie emptiness.

So, where do insects go
at this time of year?

Our future hornet queen,

use the forest's natural
insulation - leaf litter -

to wait out the winter
in a secret hideaway.

Having already mated,

the new queens will emerge from
their leafy lairs in spring.

But they won't return
to their old home.

Hornets never reuse
an abandoned nest.

The reign of this paper palace
is now over.

Whilst winter sees one monarchy
pass onto the next generation,

a different monarch
is on the rise.

A new fleet of genetically
elite, age defying,

supreme beings,
have been born...

poised to invade the US.

In these secluded
eucalyptus groves

on the coast of California,

Monarch butterflies are
arriving...

in their thousands!

[Enchanting music]

Their monumental journey began

over 3000 miles away in Canada.

The drop in temperature,
and changing tilt of the Earth,

triggered a mass exodus
in search of some winter sun.

No ordinary monarch
could fly that distance.

These butterflies are made
from stronger stuff.

They are the 'super generation'.

Born bigger, more powerful
and with the gift of longevity,

these formidable flyers
live eight times longer

than the average monarch.

Built purely
to make the migration

to this one small patch
of forest.

These eucalyptus trees
are not native to this area.

But the monarchs
have chosen them

as their perfect home
in the sun.

The trees create the ideal
microclimate for them.

The canopy and branches
provide wind protection.

And long thin leaves
filter the California sunlight,

giving the butterflies dappled
light and cooling shade

that they need.

And the slender leaves
are easier

for their little legs to grip.

They didn't find this forest
by chance.

Despite having never visited
this site before,

Monarchs have been found
to migrate

to the exact same tree
as their ancestors,

years previously.

And they know how to find
this very tree

through a remarkable sense
of direction, and time.

These tiny creatures tell the
time by using their antennae.

Coupled with super powered eyes

that decipher the sun's
position, they rarely get lost.

This migration isn't all about
the mild weather.

It also means more potential
mates to choose from.

The air fills with the scent
of female pheromones...

and long, elegant courtship
dances commence.

[Magical music]

Eventually, this super
generation's time

must come to an end.

And they will die
shortly after laying their eggs.

Leaving them to hatch
in the California sunshine.

It takes three more generations
of butterflies

to relay-race each stage
back to their Canadian homeland.

Just in time for summer.

By August, the next batch
of superpowered monarchs

will be born.

And so the ticking clock of
nature's changing seasons

starts its cycle all over again.

Every new season
brings dramatic change.

From the boom of spring,

to the challenges of winter.

These unstoppable forces are
what define the cycles of life

in our planet's seasonal forest.

[Enchanting music]