All language subtitles for PBS Journey

NARRATOR It's one of the most profound
mysteries in the natural world.

An amazing
transcontinental odyssey.

The migration each year

of millions
of monarch butterflies

from Canada, across America,
to Mexico.

CHIP TAYLOR: You've got a butterfly
that's originating in Toronto,

or it's originating in Detroit, Michigan

it's coming down

maybe even Winnipeg, and it's moving south,

and somehow,
it finds its way to Mexico.

Could you do that?

NARRATOR:
Starting from a tiny caterpillar,

blossoming
into a beautiful butterfly,

these delicate creatures
will fly thousands of miles

in a feat of endurance
and navigation

unlike anything else in nature.

LINCOLN BROWER: They've never taken
a long flight in their lives,

and they're on their way
to an area

that they've never seen before.

Somehow they're recognizing
landmarks, or following streams, I

or following the sun.

They're following something.

NARRATOR: They're on their
way to a remote area

high in the Mexican mountains,

and they get there every year
at exactly the same time.

BILL CALVERT: Butterflies have
dazzled humans for millennia.

It's a beautiful little creature,

and on top of that,
it migrates 2,000 miles.

And this just staggers the mind.

BROWER:
I think the monarch butterfly

is one of the most magnificent
animals in the world.

And it's unique in terms
of the entire animal kingdom.

There's nothing like it.

NARRATOR: Next on NOVi.

The Incredible Journey
of the Butterflies.

Captioning sponsored
by EXXONMOBIL, DAVID H. KOCH,

the HOWARD HUGHES MEDICAL INSTITUTE,

the CORPORATION
FOR PUBLIC BROADCASTING

and VIEWERS LIKE YOU.

Major funding for NOVA
is provided by the following:

ExxonMobil... taking on

the world's toughest energy challenges.

And by:

And...

And by the Corporation
for Public Broadcasting,

and by contributions
to your PBS station from:

NARRATOR:
On a late August morning

just north
of Lake Huron in Canada,

a miracle of nature is about
to unfoldo.

This tiny caterpillar
is destined

to become a monarch butterlly.

In one of the most
amazing transformations

in the animal world,

the caterpillar will outgrow
and shed its skin four times.

The fifth time,

the caterpillar disappears.

It's transformed into a chrysalis,

a delicate case within which

a completely
new being takes form.

After about ten days
in the chrysalis,

the new creature is complete.

All traces
of the caterpillar are gone.

And in its place is a butterfly

with four delicate wings.

But the newly developed
monarch butterfly

must wait a few hours for
its wings to harden.

And then, finally, it can fly.

This particular generation of
monarch butterflies is special.

Every year,

about 100 million of them begin
an astonishing migration.

Coming from Southern Canada

and the Northeastern
United States,

each butterfly,

starting on its own,

flies about 2,000 miles,

arriving two months later
in Mexico.

Their trip is part
of a carefully-timed cycle

that began
three generations back

when a group of monarchs

left Mexico
at the end of the winter.

They flew as far north
as the Gulf states,

mated and died.

The second generation flew to
the Northern United States.

[There, they, too] mated and died, I

living only about a month.

Their offspring-the third generation...

Icompleted the last leg
of the journey to Canada

also surviving only
abouta month. .

But the fourth generation
will live almost nine months.

And they'll fly
all the way back to Mexico

in one epic trip.

It's an amazing natural cycle that,

so far, eludes explanation.

IThe mystery starts at the very beginnin

of the trip,
because no one knows

exactly what triggers

the exodus from Canada.

LINCOLN BROWER: Well, when
the monarchs leave Canada,

they have a 2,000-mile trek
ahead of them, at least.

They're freshly hatched
butterflies,

they've never taken a long
flight in their lives,

and they're on their way
to an area

that they've never seen before.

Somehow, they're
recognizing landmarks,

or following streams,

or following the sun,

or following something.

We just don't know exactly how they do I.

It's really
an incredible journey.

NARRATOR: A monarch's wingspan
is just under four inches.

And they weigh less than
one-fifth of an ounce. .

So how they survive
their marathon migration

is another mystery.

They only fly
when conditions are perfect.

lf it's too cold, they get sluggisjj

and can't flap their wings.

If it's too hot,

they stop flying
so they don't get overheated.

They must also stop often
for nectar and water.

But every time they land,

there can be enemies lurking.

Bad weather is
also the monarch's enemy.

A rainstorm can be deadly.

If it survives enemy attacks
and bad weather,

a monarch that started in Canada

has to fly at least jlesajpy j

to get to Mexico.

The physical effort this
requires is remarkable

for a creature so smalli
with such fragile wings.

DAVID GIBO: Butterflies
are the worst possible

body form for trying to makel
a long-distance migration.I.

They're simply a bad design.

Every time they flap
their wings, they're using

energy at least 20 times the rate

than when they're not
flapping it.

So they're just burning
their fuel up at a great rate,

much like, say, a helicopter might.

And so, they have to compensate

for their inadequacies
by soaring.

Soaring is gliding

in rising air, much like
I'm doing right now. I.

The sun heats the ground,

the ground
heats the air above it.

As the air heats,

it expands and becomes lighter,

and begins to rise.

And pretty soon,
you have a column of rising air.

That's a thermal.

Under good conditions,
you can maintain

the altitudeyou'reat,
or even can gain altitude.

A more helpful maneuver
is to circle in it.

And you see hawks doing this

and vultures doing this
all the time.

Circling the thermal, ying within it... I

and this seems like a wonderlul
free ride, and it is.

Soaring's the key to them
getting to Mexico.

NARRATOR On the shores
of the Great Lakes,

just days into their journey,

the monarchs face
their first geographic hurdle.

Miles of open water

and constantly shifting winds.

As the monarchs
are migrating out of Canada,

they hit the Great Lakes,
which are a barrier.

They can't see across them.

NARRATOR:
With no land in sight,

monarchs use their finely tuned

sense of the direction
of the wind to carry the

across the water.

If wind from the south,
a headwind,

threatens to blow them
off course

they stop and wait.

When they sense that the wind
has shifted in their favor,

they fly on.

The ultimate destination of
their incredible journey

is a tiny area
about 60 square miles,

and 10,000 feet high
in the mountains of Mexico.

IThe local people, I called the Mazahua,

have lived here
for hundreds of years.

They believe monarchs
epresent the spirits I

of their ancestors.

And the arrival I of the butterflies

each year, begins a celebration

called the Day of the Dead.

ALICIA GARCIA:
It's a very beautiful time

when the butterflies arrive.

The butterflies
would come down, surround us.

Coming down
to give the final touch

to the tradition
of the Day of the Dead.

For those who live here,
it's our belief,

from when I was a child,
I we would say they

“the souls
of our departed loved ones.”

Every year I make an altar.

We put these things here

because when our ancestors
were alive,

this is what they liked.

That's why one waits
for their arrival:

To give them this offering.

HOMERO ARIDJIS:
The legends of the people

that live near the ocean
and the mountains,

are important to them.

For us,
there is a sense of the space.

The freedom to fly,

to fly with imagination,

to fly just like a butterfly.

NARRATOR Homero Aridjis is one
of Mexico's best-loved writers.

He grew up in these hills

and has fought
to preserve them for monarchs.

Every year,
Lincoln Brower comes here

to continue his study
of the monarch migration.

When you were a young boy, Homero

you used to go up to
see the butterflies? I.

Yes. Every year, we came

with the schoolchildren.

And for us,

it was one of the most fantastic
spectacles of the year.

To go to the plain of the Mule

to see the butterflies.

Butterflies also came to town.

They were across the street.

They flew through the town?

Exactly.

They were looking for water.

Sometimes they was
in your house.

But there were millions
of butterflies.

And for us,

it was a spontaneous miracle

to see butterflies here,
in the Cerro del Campanario.

But we didn't know that
they were coming from Canada,

across the United States.

And the Canadians
and Americans didn't know

that they were coming
to these places.

NARRATOR: It was not until 1975

that scientists discovered
the full extent

of the North American migration,

when butterflies
that had been tagged in Canada

were found spending
the winter here.

These monarchs return each year

to 12 specific sitesi in these mountains.

This is their only destination
in the world.

It's a perfect environment
for the butterflies

because of the unique climate.

BROWER:
We're talking constantly

about this micro-climactic
envelope.

About 3,100 meters,

usually on southwest-facing
slopes.

If you imagine the forest
as a blanket

that protects the butterflies
by keeping the heat in,

and also think of it

as an umbrella
that keeps the rain out,

and the tree is like a hot water bottle.

It's radiating heat out through
the bodies of the butterflies.

So, when the temperature drops
down really low,

you'll see millions of monarchs

just festooning
these beautiful trunk clusters.

If you think about it,

the bigger the tree,
the more heat it holds.

So this is an argument

for maintaining the forest
in its native state.

To let the trees get as big as they can,

and the butterflies will be protectedi

during those cold periods.

NARRATOR: Monarchs live in other parts
of the world, in warm climates.

But only Canadian
and North American monarchs

migrate such
an incredible distance

to avoid the certain death
of a cold winter.

And exactly how they navigate

from Canada to Mexico
is another unsolved mystery.

Scientists only have
a few clues.

One theory is that
the butterilies navigate

by following a specific angle
of the sun

in relation to the earth.

Another theory proposes

that the earth's magnetic field

may provide a subtle 9fljji9j gir.

And recently, biologists
discovered specific cells

in the butterfly's brain

that regulate
their internal clock

and help keep them on course.

At the University of Kansas,

Chip Taylor studies the forces
at work

in the monarch migration.

TAYLOR: You've got a butterfly
that's originating in Toronto,

or it's originating
in Point Pelee, j

or it's originating I
in Detroit, Michigan,

it's coming down

it's maybe even Winnipeg,
and its moving south,

and somehow it finds its way
to Mexico.

Could you do that?

And so now you need to tell

whether or not
it's a male or a female,

and so, this picture...

NARRATOR: In 1992, Taylor started
a project called Monarch Watch.

Are there any over here? No.

So you know that one's a girl.

So let's check out iyour butterfly. I.

NARRATOR: School children and
teachers tag butterflies

from all over
the Northeastern United States.

The tags don't hurt
the butterflies,

and don't affect their ability to fly.

Oh, there he goes.

NARRATOR: But when tagged
butterflies are recovered

at various stops
along the way to Mexico,

tracing back the information
on the tags

helps reveal their flight path,

and their traveling speed.

Let her go.

NARRATOR:
And one of Taylor's tagging experiments

had a surprising outcome.

TAYLOR: We ran some
experiments a few years ago.

So we took butterflies,

and we transferred themi Jngton, D.C.,

and initially,
when we released them

in Washington, D.C., they behaved as if

they were still in Kansas.

NARRATOR: The butterflies who'd been
moved to Washington started out flying

in the same direction
they would have taken to Mexico

from their original home
in Kansas,

almost directly south.

But starting from Washington,

that flight path would never
get them to Mexico.

Amazingly, after a few days,

the displaced monarchs
somehow reoriented themselves

and changed course
to a strong southwest heading.

That meant that even starting
from an unfamiliar location, j

they still ended up
in the right place in Mexico.

TAYLOR:
Now this is really exciting stuff,

because what this says is
that somehow

this butterfly is acquiring
celestial information,

perhaps magnetic information,

and it's integrating those

and remodeling the physiology
of the system

to have a different vector,

to have a different direction
from where it came from. I.

Now that's pretty cool.

NARRATOR: By late September,

aboutamonth I into the migration

the monarchs are gathering
into huge flocks.

By this time,

they've traveled more
than halfway across America...

over the industrial belt...

through small
Midwestern towns...

across the Great Plains...

and finally,
approaching the Southwest.

No one knows how many monarchs
die along the way.

But if they make it to Mexico,
there's another threat.

Their destination in the
Mexican mountains...

the forests that will keep
them alive over the winter...

is in danger.

It's, like, you see alli
these trees, Lincoln?

Yeah.

Before, there were
hundreds of thousands,

land now, you can count them.

And then, they're all...

You see very tall and very wide.

NARRATOR: In 1986, the Mexican
government protected some sections

of these mountains as official sanctuaries

for the butterflies
for the winter months.

But that meant some parts

of the forest local people
had depended on for income...

through legal
logging operations...

were suddenly off-limits.

The result was an unexpected
new threat to the monarchs...

illegal logging.

BALTAZAR GUTIERREZ:
We all have needs,

but those
that cannot meet their needs...

they are the ones
doing the clandestine logging.

WOMAN: They come
at 2:00 or 3:00 in the morning.

They go down in the night

to sell the wood.

NARRATOR: Mexican police
patrol the forest,

but have not been able
to stop illegal logging.

The World Wildlife Fund
pays villagers

to try to stop the destruction,

but they are no match for
the dangerous forces at work.

EDUARDO SALINAS: Logging is
clandestine and involves dangerous people.

So you cannot go around telling
the world about it.

Sometimes you find
yourself alone,

and even with the police,
you can be left alone.

They will follow you
to kill you.

It's not that easy.

MAN: Who would allow
their children to die of hunger?

We know that it's important
to preserve the forest

for the butterflies.

But because of our need,
we have not been able to do it.

BROWER: We're talking about
hundreds of hectares of forest

being leveled and then burned.

I have been told that
the reason they burn them

after they log them is, I
“to destroy the evidence

that they cut them,”

which sort of eludes
my thinking, completely.

Even this small-scale logging
operation is destroying

the capacity of the monarchs
to use those sites.

There are so few trees left,

and even if they did sit on
the ones that were left, j

they'd freeze to death.

NARRATOR:
With the sanctuaries shrinking,

an unusually cold winter in
Mexico can be a disaster

for the butterflies.

During one storm,
80 percent of them died

in a single sanctuary.

If a harsh winter is followed
by more bad weather

in the spring, then no one knows

how many butterflies will be
able to breed new generations

for future migrations.

BROWER:
If the numbers are reduced

to the point where the migration
starts to unravel,

we don't know what the critical
low number is,

but I'm worried that we might
just get close to it.

NARRATOR:
It's the middle of October.

The butterflies are
almost to the Mexican border.

They started the migration
scattered across

thousands of miles of the
Northeastern U.S. and Canada.

But at this point, they're
flying together in a huge flock,

only 50 miles wide, I
for the final leg south.

I just saw the shadow of it.

NARRATOR: For over 30 years,

Texas zoologist Bill Calvert
has conducted

extensive field studies
of the migration.

But this year, he's worried...

the butterflies are late.

Well, this is perlect...

except for one thing:

No butterflies here.

An endangered phenomena
would not be the same

as an endangered species.

In the case of an endangered
species, of course,

we're worried about
all the members disappearing.

In the case of an endangered
phenomena, we're worried I

that the migration would be
reduced to such a state

that it would be unnoticeable,

or maybe even the migration
itself would disappear.

I mean, the predictions are
that this is going to be

the lowest population ever.

NARRATOR:
So far, he's only seen a single monarch.

Well, it's in pretty good shape.

It's got a couple pieces missing
out of a wing over here,

but otherwise,
it's in pretty good shape.

There he goes, off to Mexico.

NARRATOR: At the end of
the day, Calvert decides

to take one more look in a
secluded corner of the woods.

CALVERT: Let's see what
we've got in there.

Oh, wow.

Look at them up there.

My God!

It's just fantastic!

Whoa, there are hundreds
of thousands

passing us right now.

Butterflies have dazzled humans
for millennia.

It's a beautiful little creature,

and on top of that,
it migrates 2,000 miles,

and this just staggers the mind.

NARRATOR: The butterflies
have been traveling

for six weeks from Canada.

But they still face the most
treacherous part of the journey.

They must fly over hundreds
of miles of scorching desert

and navigate the towering
Sierra Madre Mountains.

CALVE RT:
Something has to focus them.

I think the Sierra Madre
mountains serve that purpose.

The mountains stick up'
pretty high.

The butterflies encounter them,

and they turn
and they follow the mountains,

and they can follow
the mountains for 900 miles.

NARRATOR:
Late October, in Mexico.

The butterflies are expected soon...

and the Mazahua people prepare
to welcome them.

MAN: It's a privilege
that God has sent us this insect.

We take advantage of the months
that the butterflies are here

to earn our living.

Because the truth is

that we have a community
that is quite poor.

In this season, we earn enough
to make a living.

It's not a lot of money,
but you can rely on it.

NARRATOR: As they wait
for the butterflies,

the Mazahua pray for their safe arrival, I

along with the spirits
of their loved ones. I.

It's now the first week
in November.

NARRATOR: After two months and
thousands of miles of flight,

the butterflies have finally
reached safety.

Millions of them arrive
over the next few days,

and the people rejoice.

Now, with their long journey
finally behind them,

the monarchs rest.

They huddle together
in huge clusters,

and cling to the trees
for warmth.

They'll leave the trees
occasionally

to feed on nectar and water.

But they return I to these clusters

and stay here
for almost five months.

When spring arrives,

the butterflies bloom again.

They open their wings
to the sun,

warming up for flight.

Most of these monarchs will
travel back to Texas.

There they will stop to mate.

Each female will lay 3OO

to 400 fertilized eggs.

After the eggs are laid,

the parents will die.

When the new generation hatches,

it will keep flying north,
mating along the wayj.

A third generation will do the same. I.

And almost a full year
since the migration began,

that special fourth generation
of monarchs

will be born in Canada.

And the miraculous migration
will begin again.

BROWER: I'm frequently asked, well,
“What difference would it make

if we lost
the monarch migration?”.

And I say, “What difference
would it make

“if we lost the Mona Lisa,

“or if we lost Mozart's music?

It's part of our culture.”

I think the monarch butterfly is

one of the most magnificent
animals in the world.

It will absolutely floor anybody
the first time they see it,

as it did me the first time
I saw it.

It's one of the wonderful
planetary cycles on this earth.

And it's unique in terms
of the entire animal kingdom.

There's nothing like it.

It's really
an incredible journey.

On NOVA'S “The Incredible Journey
of the Butterflies” Web site,

watch any part of this program
go behind the scenes and more.

Find it on pbs.org.

Major funding for NOVA is
provided by the following:

ExxonMobil... taking on

the world's toughest energy challenges.

And by:

And...

And by the Corporation
for Public Broadcasting

and by contributions
to your PBS station from:

Captioned by Media Access
Group at WGBH access.wgbh.org