Nova (1974–…): Season 47, Episode 8 - Eagle Power - full transcript

Up-close footage provides a look at the strength, eyesight and flying skills of an eagle, and reveals the danger and drama of chicks as they struggle to survive.

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and deadly.

From mountaintops

to river valleys,

eagles rule the skies.

Strong enough to take
down enormous quarry,

they are the
ultimate bird of prey.

By following a family
of bald eagles...

This is our national symbol.

These are powerful birds.

Witnessing eagles in action...

She's doing

eight, nine, ten
miles an hour... Up!

And that's fast.

And by joining one man
and his feathered friend,

these icons of the air
will be put to the test...

What a girl!

That is actually
very, very impressive.

To reveal what it takes

and even what it feels like...


We're flying with
a golden eagle.

To be the most
powerful bird in the sky.

"Eagle Power."

Right now, on "NOVA."


It's late winter in Iowa.

Under the most recent snowfall,

this bald eagle
is trying to protect

her most precious possessions.

These two eggs must be kept
at around 99 degrees Fahrenheit

to hatch successfully.

At night, temperatures
plummet to minus 13.

By day, it's cold enough
to freeze her eyelashes.

But she'll do whatever she
can to keep her eggs safe.

This nest has been
rigged with cameras

to reveal what it
takes for these eggs

to develop into
top aerial predators.


Bald eagles are just one of
around 70 different species

in the eagle world,

every one a mesmerizing
blend of power and beauty.

They've conquered a huge
range of habitats across the planet,

from harpy eagles in the
rain forests of South America

to Steller's sea eagles
in the icy North Pacific

and fish eagles in the
great lakes of Africa.

They live at the top
of the food chain.

But to dominate their world,

they must overcome
three major challenges.

They have to cover
hundreds of miles on the wing,

spot their prey
at vast distances,

and tackle the largest quarry

of any bird species.

To reveal exactly how
eagles achieve this...

We need access
to a remarkable bird.


This is Tilly, a golden eagle

with a wingspan of
almost six-and-a-half feet.

Similar in size to a bald eagle,

golden eagles range across
much of the Northern Hemisphere,

including Asia, Europe,
and North America.

But what makes her special
is the relationship she has

with her lifelong partner,

Lloyd Buck.



Hello, my love.

You enjoying yourself, eh?

You're the best, ain't you?

You're a once-in-a-lifetime
bird, you are, eh?

I'll never have another
bird like you ever, will I?

Since he was a child,

Lloyd Buck has been
obsessed with birds.

At his home in North
Somerset, England,

he has special licenses
to keep and train

many different species.

But one particular
bird stands out... Tilly.

They have been
together for 20 years

and have forged an
exceptionally close bond.

Tilly behaves as if
Lloyd is her mate for life.

Go on, go and enjoy
yourself, my love.

I wish I was you.

I wish I was you!

Thanks to Lloyd's
dedicated work with Tilly,

she acts just like a wild
eagle, but is also comfortable

around scientific
equipment and cameras.

Their unique bond provides
a special opportunity

to learn more about these
remarkable predators.

Eagles are such
inspirational birds.

There's so much, I think,

that we don't
understand about them,

and that's what I'm
hoping to learn here,

a little window into her world,

into the world of eagles.

Together, Lloyd and Tilly

will take on a series
of tests that will unlock

the science of eagle power.

In Iowa, it's the
first week of April,

and the female seems restless.

One of the chicks
is starting to hatch.


After 37 days of incubation,

it uses a tiny egg
tooth on top of its beak

to crack the shell
in a bid for freedom.




Three days later, it's
joined by its sibling.

Even at this young
age, they need to eat

almost half their
body weight in meat

every day.


help is on hand to
bring in fresh supplies.

This is the male,

and as with all bald eagles,

he's about 20%
smaller than his mate.

It's thought she might be bigger

to help produce and
incubate the eggs.

Bald eagles
normally pair for life,

but the female's
previous partner

has disappeared,

so this male is new.

The breeding season
can last around ten months,

so rearing the chicks
will be a real test

of their new relationship.

The chicks' weight can
increase by a staggering 500%

in their first week.

So the adults spend
much of the time hunting.


Bald eagles are
masters of hunting fish.

They can make up
to 90% of their diet.

They are able to pluck their
prey from the water surface

with incredible precision.

But rabbits and squirrels
are also brought to the nest.

For now,

the partnership of the
mother and her mate

is providing all the
food the chicks need.

Eagles around the world
catch a huge variety of prey,

so they have a range
of hunting techniques.

In the mountains of
Oman, this Verreaux's eagle

is after a terrestrial target.

Rock hyrax.

These small mammals are
equipped with special vision:

a shield on their iris

that cuts out glare,

helping them spot the
predator, even in bright sunlight.

But this eagle is just a decoy.

Verreaux's eagles hunt in pairs.

One flies in plain sight,

distracting the hyrax.

While the second eagle
hugs the contours of the land,

staying hidden...

Until the last moment.

Catching quarry like this

is a dangerous task.

There is no room for error.


When eagles hunt airborne
prey, if something goes wrong,

they have more space and
time to get out of trouble.

They can even escape a glancing
blow with the water surface.

But when the prey is on hard
ground, it's a different story.

One wrong move could
result in a deadly collision.

Especially with
large, heavy prey.

There is no margin for error.

They must capture their
victim without mistake.

So exactly how do
eagles catch prey on land?

To find out, Lloyd
has come to Scotland

to put his golden
eagle, Tilly, to the test.


But first, he needs
something for her to hunt.

This is robo-bunny.

Designed and created
by tech wizard Chris Watts,

with a fake fur coat
and high-speed motors,

it can blend into
the undergrowth

or flash across the open.

It's fitted with an
onboard 360 camera

to help capture
all of the action,

and a bit of bait to
get Tilly's attention.

Okay, she's gonna rouse.

Get ready.

Okay, go, go,
go, go, fast, fast!

In a matter of seconds,
Tilly locks on to her target.


She's got him, she's done
it... Thank you very much, Tilly.

Good girl.

To challenge
Tilly's hunting ability,

they repeat the test
in different conditions.


From strong winds
and overcast skies

to bright sunlight.

But the outcome is the same.

Tilly wins.

To reveal the secret
to her success,

the team needs to
go through the footage

frame by frame.

First, Tilly keeps a constant
lock on robo-bunny's position.

Next, she uses her wings
to adjust her trajectory

as the wind changes
or the target moves.

She keeps her legs tucked
in to stay aerodynamic.

Then, just a quarter of
a second before impact,

she swings her feet forwards

so both eyes can see
robo-bunny and her talons.

And she makes perfect contact.

But there is one more element...

Okay, get ready, Chris.

To Tilly's hunting ability.


Robo-bunny weighs
about 13 pounds,

times more than Tilly.

Remarkably, not only
can she strike robo-bunny...

She can lift it into the air.

She even has the strength
to pick it up with one foot...

An amazing
achievement for a load

weighing 150% of
her own body weight.


What a girl!

Good bird, there's a good eagle.

Tilly's abilities have exceeded

all of Lloyd's expectations.

She's able to do this thanks
to the most important weapon

for any eagle...


As veterinarian
Michael Jones explains.

Eagle talons are very
well adapted for killing prey.

Not only do you have
the strength in their feet,

but you also have
this talon size, as well.

The harpy eagle has
some of the largest talons

in the world,

measuring nearly five inches.

The talons are largest
on digit one and digit two,

and those are the ones
that typically hold the prey.

Unfortunately for the prey,
because they are so powerful,

the prey is usually
going to succumb

to either extreme pressure,

multiple puncture wounds
to the body and vital organs,

or blood loss.

To do this, eagles have
to grip with enormous force.

But what is most impressive is,

they can hold this
crushing pressure

for a long time
with little effort,

and it's all thanks to some
impressive mechanics.

Their feet have an
in-built ratchet system.

The tendons in
their toes are ridged,

and so is the
tissue around them.

This creates a simple
locking mechanism,

so the surrounding
muscles can relax

without losing any grip force.

Many bird species
have this adaptation,

but in eagles,

the ridges are
particularly large

to cope with the enormous power.

Creating and maintaining
such a high force

is a critical part of
an eagle's armory.

And it helps them hunt
even the largest prey.

But these super-strong weapons

have a second,
essential, purpose:

to fight.

Winter in the Alps
is desperately bleak.

Golden eagles soar above the
snowy peaks in search of prey,

but food is so scarce here,

they frequently
turn to scavenging.

A dead fox.

It could support this
female eagle for days.

Such a prized meal is in demand,

and a devious mob of
crows will try anything

to steal a mouthful.

A flash of talons seems
enough to remind them

who's at the top
of the food chain.


But these annoying crows
are the least of her worries.

The biggest threat
comes from her own kind.



A meal like this attracts
eagles from miles around,

and, if needed, they'll
fight for the food.

In battle, talons are
their weapons of choice.

They use their long
legs to keep their head,

and, importantly, their eyes,

away from danger.


They must fight to survive.

In Iowa...

Our bald eagle youngsters are
now one-and-a-half weeks old,

and still defenseless.

Even the slightest
thing can pose a threat.


Somehow, one has become
tangled in the female's feathers,

and it's at risk of choking.

It's hard to know how
this has happened.

Even the mother seems
confused and stressed.


The more she moves around,

the more she pulls
on the chick's neck.

It's a lucky escape.

But now it's stuck on its back.

Dad's busy looking
after the other chick,

and doesn't seem
to want to help.

Less than half of
all bald eagle chicks

will survive their first year.

The odds may be against it,

but those powerful
talons come to the rescue.


Over the next few weeks,

the parents will bring
in around five fish a day

to help the chicks grow.

And by a month old,

some obvious
changes start to show.

Their fluffy thermal down,

which has kept them
warm all this time,

is slowly being covered
by juvenile flight feathers.

These will continue to grow

until they reach
their maximum length,

around the time they fledge.

But perhaps the most
important change is in their vision.

Their eyes open
within hours of hatching,

but much like a human baby,

it’s thought they're
born with poor sight.

It takes a few weeks for
their eyesight to sharpen

and become one of the
most powerful senses

in the animal world.

Eagles' vision is phenomenal.

They have different
areas in their retina

that allow them to have
increased visual acuity.

It's very important that
they have that visual acuity

to be able to capture their prey
and be successful in the hunt.

We describe anyone
with exceptional sight

as "eagle-eyed."


But just how good is it?

To find out,

Lloyd Buck has brought
his golden eagle, Tilly,

to a remote part of Scotland.


They're joined by
Professor Graham Martin,

an expert in avian vision.

I'm intrigued to learn more

about just how
good her eyesight is.

Okay, well, I think we
can set something up.

A sort of game of hide
and seek, perhaps?

Tilly must find Lloyd
somewhere in this landscape.

Her cage has been
covered, so she can't cheat.

Lloyd has found a position
one-and-a-half miles away

on the other side of the glen,

and weather
conditions are not ideal.

Even with a powerful
telephoto lens,

it's hard to pick out
Graham and Tilly.

It's a long way.

I cannot see you without
a pair of binoculars,

and even with the binoculars,

there's that much
moisture in the air, so...

Let's see what she does
now... This is the big test.

Okay, then, well, I'll, I'll
release her now, okay?

Okay, good luck...
Come on, Tilly.

Come on, Tills.

She's off.

She's looking very hard.

I'm sure she's
trying to find you.

Tilly has never faced
a challenge like this,

but she appears to spot
Lloyd almost immediately

and makes her way to
the other side of the glen.

Come on, Tilly, come on!

Tilly takes an indirect route,

riding a series of
strong air currents

to reach Lloyd more efficiently

and much faster.

She's coming in, she's
coming in fast, whoo-hoo!

She's done it, Graham.

Absolutely hammering
across the valley.

What a bird she is.


You clever bird.


What an eagle you are, eh?


Graham, she's on my arm.

That is absolutely incredible...
I'm so pleased with her.

I've never asked her
to find me like that.

That is actually
very, very impressive

because it took really
very little time at all.

Tilly spotted Lloyd in
this enormous landscape

from a mile and a half away,

a feat so impressive, it
seems almost super powered.

So how does she achieve this?

Much like a human's
eye, images are projected

onto the retina at the
back of the eagle's eye.

This area is covered with light
sensitive cells known as cones.

The more cones, the
sharper the eyesight.

A human eye may have 200,000
cones per square millimeter.

But eagles can have
over twice as many,

giving them the
sharpest eyesight

of any vertebrate animal.

The eagles'
supreme visual acuity

gives them a huge advantage.

It means they can quickly pick
out prey in a vast landscape.

But there's an
unexpected downside

to having such sharp vision.

The problem is you don't
want to get the sun in your eyes.

It would destroy all the
very high acuity it's got.

So they have these big eyebrows,

it's like wearing
a baseball cap.

Yeah. That's all designed

to keep the sun
out of their eyes

so they don't actually
ever image the sun.

This brow ridge is
what gives eagles

their fearsome stare.

But it has a serious drawback.

Of course, if you've
got... keeping the sun

out of your eyes, you can't
actually see what's up there.

What an eagle
wants to do is patrol

and look down at
the big terrain below it,

and it's bending
its head forward,

it's tipping its head
down to have a look.

And that means
that this blind area

which is designed to keep
the sun out of their eyes

is stopping them actually
looking where they're going.

This blind spot is not
normally a problem.

In their natural environment,
they soar high above the trees.

But in a modern landscape,
it can be a fatal flaw.

Across the world,

eagles are colliding with
man-made structures.

Wind turbines,
which are often built

in wild landscapes,
are a particular problem.

So, at this wind
farm in Wyoming,

scientists like Misti Sporer

are trying to
protect the eagles.

This is the eagle
observation tower.

So when they see an
eagle enter into the area

where the turbine blade
would pass through,

they will shut that turbine down

and the eagle is able to pass
through the area going unharmed.

And then once
that eagle has left,

they start the turbine back up,

so we can continue
generating electricity.

So, we do lose a little bit of
energy throughout the process

but it's worth it
to save an eagle.

But human eyesight
isn't always reliable.

When an eagle flies
against the sunlight,

it can be hard to spot.

So this wind farm is now
using artificial intelligence

to improve their odds.

Identi-Flight utilizes eight
cameras around the bottom,

so it can see in 360 degrees.

There are two cameras up top

that are capable
of tracking an object

as it flies through an area.

In just one second, the
system can figure out

if a flying object
is an eagle or not,

and only if it flies too close

will it temporarily shut
down any turbines in its path.

It's over five times
more effective

at seeing birds than humans,

meaning the eagles
here are now much safer.

But across the world,
the biggest threats

to eagles are still humans.

In areas around the tropics,

deforestation is
threatening jungle species

like the Philippine eagle...

And the harpy eagle.

There are fewer trees
for them to nest in...

And far less prey
for them to hunt.

Many eagles are also
dying from lead poisoning,

as hunting ammunition
contaminates leftover carcasses.

In total, more than a
third of all eagle species

are considered to be
endangered or vulnerable.

In the past, conservationists
have been forced

to take drastic
action to save eagles

on the brink of extinction.

During the 1940s,
DDT, a potent insecticide,

was sprayed widely
across the U.S.

to treat pest problems,
large or small.

It was even sprayed on
humans to rid them of parasites.

But DDT seeped
into the ecosystems

and passed from
prey to predator,

so those at the top,

especially eagles,
were hit hard.

It caused a thinning
in eagle eggs,

so they often cracked
during incubation,

and it almost wiped them
out from parts of the U.S.A.


In 1972, DDT was
banned in the U.S.,

and some extreme conservation
measures were launched.

Eggs were taken from the wild,

hatched safely in captivity,

and the chicks were
returned to the nest

to be reared naturally.

And it worked.


There are now thought to be
over 140,000 bald eagles in the U.S.

It's a truly
remarkable comeback.

In Iowa,

the eaglets have their
own dangers to deal with.

They're now eight weeks old,

and have undergone
some remarkable changes.

They're nearly fully grown,

and their feathers are
almost entirely black.

But something seems
to be bothering them.

A wet spring has
created ideal conditions

for an infestation of
blood-sucking black flies,

and they're
attacking the eaglets.

Black flies, which are
also called buffalo gnats,

pose a problem for young chicks,

not necessarily
because of a single bite

but because they often attack
the chicks in large swarms

and you get
multiple bite wounds.

And typically
chicks will succumb

to either blood loss or
even anaphylactic shock

related to the bite.

As weather patterns
change year after year,

the number of black
flies seems to be

getting higher in this region,

and this season
is especially bad.

It's almost certainly
making the chicks weaker,

but worse still,
the constant biting

is making them restless.

One youngster becomes
so uncomfortable,

it climbs the tree to get away.

70 feet up, this
is a risky move.

It's too young to fledge,

and too weak to deal
with the strong wind.

In desperation, it leaps...

and falls to the ground.

The team monitoring
the nest raise the alarm

and send out a search party.

But, in the meantime,
the youngest chick

is also driven from
the nest by the flies.


It still doesn't have full
control of those big talons,

and one mistake is all it takes.

It's a catastrophe.

Somehow, the search
team find it alive,

covered in black fly bites.

But, unfortunately,

the eldest chick is still
nowhere to be seen.

If the chicks were older,

they could have flown to safety.

But they didn't
have time to develop

the strength and
coordination required

for one of the eagle's
most essential skills...


If you have the opportunity,

just watch an eagle fly,
you can certainly appreciate

their majesty, their
grandeur, their ability.

Watching an eagle
soar is freeing,

it's gratifying,
it lifts you up.


Eagles dominate the sky.

They can dive at around
150 miles per hour.

And perform surprising
aerobatics when they fight

or display to a mate.

And one of their
greatest aerial abilities

is soaring.

Golden eagles can
have a home range

of over 1,000 square miles.

To cover such vast distances,

they use air currents to
push them high into the air

without flapping their wings,
saving them precious energy.


It's something Lloyd
Buck has always

wanted to know more about.

So he's come to California,
where paragliding expert

Michael Vergalla often flies
alongside wild birds of prey.

By learning what it
takes to fly a paraglider,

Lloyd hopes he will understand
more about how eagles soar.

Bring the wing up
in three, two, one.

Wing's coming up.

Okay, walk, walk, walk, walk.

Start running... run, run,
run, run, run, run, run, run, run!

All right, Lloyd.

Okay, here we go.

We're flying. We're flying Mike.



I've seen Tilly do
this so many times

and now I'm doing it.

Just like an eagle,

Mike is trying to gain altitude

by harnessing two
common air currents.

Thermals form as the
sun heats the earth,

which in turn warms
the air above it,

creating a rising column of air.

Updrafts are created
when horizontal winds

are deflected
skywards by a ridge.

Mike searches for tiny clues

to help find these air
currents and climb higher.

You're looking for
changes, you're smelling,

you're listening, you're
trying to use all of your senses

to figure out what's happening.

This is what Tilly feels,
this is what Tilly does,

this is what eagles do. Uh-huh.

One of Mike's favorite ways

to find a good thermal

is to watch and
follow the local birds.

We've got another
bird on this ridge here

that we can try to join.

Mike can tell how
strong a thermal is

by seeing how
quickly the birds climb.

And it's not long before
they spot a special species.

Look out at the
end of the ridge.

Do you see the birds?

That's a goldie.

That's a golden eagle. Yep.

Let's get it, let's go.

We're flying with
a golden eagle.



I've waited my whole
life for this, Mike.


This is the thing that I've
dreamt about since I was a boy.

And my whole life I've
experienced it through my birds.


But now I've experienced
it for myself for real with you

and this is just...

I can't put that into words,

it's really quite
moving I would say,

it's quite emotional.

It's okay, you
can cry. I've cried.

I feel quite...

I feel very emotional actually.


This is something, Mike,
I'm never going to forget

for the rest of my life.

For Lloyd, soaring on
the air currents is pure joy.

But for eagles, it's a critical
component of their daily lives.

To be a dominant
predator of the sky,

they must harness the
wind to cover their territory,

and they make it look easy.

To find out just how
good eagles are at soaring,

Lloyd wants to
put Tilly to the test.

He's fitting her with a
highly accurate GPS tracker,

to measure how fast
she can gain altitude.

And a 360-degree camera
to see how her wings

are adapted to soaring.

We'll know exactly
what you get up to, eh?

You're a good girl, yes.

Go on, off you go. Go on.

Tilly quickly finds an updraft

and soars high above the glen.

You make it look so easy, eh?

The 360 camera provides
a wonderful opportunity

to see the world from
an eagle's perspective.


Throughout the flight,

the GPS tracker
and accelerometer

on her back have been
collecting vital information.


Good girl, clever eagle!

Professor Jim Usherwood,

a locomotion specialist,
can help interpret the findings.

Well, it's really exciting,

especially to having
the video next to her,

you can really see what's
happening all the way through.

We can see her climbing,
circling seven times,

and then reaching quite a
height really very quickly.

She's doing... ooh, three,
four, five meters a second

up. BUCK: Wow.

And that's fast. Yeah.

That's sort of eight,
nine, ten miles an hour up.

Imagine running
up a ladder that fast.

So she's climbing quickly?

Really fast,

while hardly travelling
across the ground at all.

Tilly climbs at this rate

without flapping her wings,
saving huge amounts of energy.

Eagles are able to ride
the air currents effectively

thanks to their large wing area,

but the shape of their
wing is different compared

to many soaring specialists.

Albatross have narrow
wings up to 11 feet long,

which generate a lot of lift

for relatively small
amounts of drag.

This wing shape
is perfect for gliding,

but it's no good to eagles.

Long wings are very good
for gliding and soaring,

but they're
horrible for flapping

and of course this
thing, at some point,

will need to flap. Yeah.

She'll need to flap to take off,

carry the weaponry
to kill something,

and then carry that
food back home,

at which point you don't
actually want super-long wings.

Eagles have to deal with
some competing priorities.

To soar well, they
need to be lightweight,

with extremely long wings.

But to hunt large prey,

they need to be
powerful and heavy,

with shorter, broad wings

that aid maneuverability
and takeoff.


Eagles achieve both...

They manage to create lots
of lift with limited wing length.

So how do they do it?

A key secret is at
the end of their wings.

From Tilly's 360 camera,
it's possible to see

that the feathers on her
wingtips are separated.

Each one of these
primary feathers

acts like a tiny aerofoil,

helping air hug the
upper surface of the wing.

It means eagles
can tilt their wings

at very steep angles on takeoff,

generating lots of lift
to support a heavy load.

It's also thought
these slotted wingtips

can reduce elements of drag,

helping them soar
with greater efficiency.

It's a powerful
solution for a wing

that has to perform
so many tasks.

The eagles' dominance of the sky

is partly what has made
them such iconic creatures.

And why they
feature so prominently

in cultures around the
world, including many

Native American tribes.

Only the eagle

can fly high enough
and far enough

to actually see the face of God.

We are truly a
people of the eagle,

and it comes out in our dress

and everything about
our ceremonial presence.

William Voelker

is a member of the
Comanche tribe in Oklahoma

and has set up a
special eagle sanctuary

to help support
their traditions.

So to take an eagle feather

and to call on the energy
of this messenger bird,

it's our direct link
with the almighty.

So the eagle is essential
in our spiritual way of life.


Historically, eagles
and their feathers

have been taken from the
wild to supply these traditions,

often resulting in
the death of the birds.

But times are changing.

An eagle can no longer

forfeit its life to benefit
culture, anybody's culture.

Those days are gone.

In today's world we have
a cultural responsibility

to doing everything we can
to enhance eagle populations.

At his sanctuary,

William has successfully
raised and released

over 400 eagles and
hawks into the wild.

He also cares for
many more in captivity.

And as these birds
naturally molt their feathers,

William passes them on
to Native American tribes

so the wild populations
can be left unharmed.


Back in Iowa, the
nest remains empty.

But remarkably,

the eldest eaglet has
also been found alive.


It was discovered washed
up downriver with a broken leg,

five days after it
fell from the nest.

Both eaglets were taken

to a raptor rehabilitation
center for treatment.

It's a reminder that although
eagles are an apex predator,

they sometimes need our help.

Over the next several months,

the eldest eagle's
leg gradually heals.


With care and support
from the raptor center's staff,

both eagles grow stronger.

They're given space to develop
their powerful flight muscles.

Finally, the youngest eagle
is ready to be released.


At last it has its own
freedom and independence.

Almost six months later,
its sibling's leg is healed...

and it, too,
returns to the wild.


By following the journey
from egg to eaglet,

we've seen what challenges
an eagle must overcome

to survive its first year.

And a very special
eagle, called Tilly,

has helped reveal the secrets
behind their greatest abilities,

like their unrivaled vision...

And she's coming
in fast, whoo-hoo!


Their hunting techniques...

and their remarkable soaring...



and skill.

Revered around the world,
these stunning raptors can't help

but inspire with their
magnificent eagle power.