Original subtitles

Over the last three years,

the Earthsounds team has captured the sounds of the natural world

across all seven continents like never before.

That's a lovely rumble.

But these recordings tell a bigger story.

As our planet faces climate change and is losing wildlife...

we're discovering that listening to nature...

Wow, this is brilliant.

...could provide vital clues to help us protect it.

In this special episode...

There it is. Yeah. Right there.

...we follow scientists who are using sound in revolutionary ways...

to help save endangered species

and our wildest places.

The pioneering idea of using sound for conservation

started 50 years ago with sound recording legend Bernie Krause.

And we're recording.

Bernie has been returning to Sugarloaf Ridge State Park in California

at the same time each spring

to capture a sonic snapshot of the entire habitat.

What we're doing is recording the dawn chorus

and the dawn chorus is the time of day

when the animals really express themselves at their most vital.

It's a magical moment.

Well, right now I'm hearing California quail.

Song sparrows.

I'm hearing a pileated woodpecker knocking in the background.

And let's see what else?

I hear my stomach rumbling.

These natural sounds are known as a biophony,

the richness of a soundscape.

This biophony is the sound of the natural world. It's its voice.

When it sounds robust,

when all the animals have a place in the choir,

it's a healthy habitat.

When they don't, it's not.

The importance of Bernie's recordings

became clear when disaster struck California's forests.

Well, in October 2017, there was a huge fire.

California's Thomas Fire already more than 270 square miles.

And 70% of this part was burned.

The destruction was extreme.

But clues that the forests were already suffering from a warming climate

can be heard in the bird song years before the fires hit.

Right now, we're looking at soundscapes from Sugarloaf Ridge State Park

and what we have on the screen is a spectrogram,

a graphic illustration of sound.

And what I'm showing is the change that's occurred over time

as a result of climate change.

When Bernie's study started, Sugarloaf Ridge was full of life.

In 1993, the density and diversity of the birds is fabulous.

There are probably 20, maybe 25, different species of birds.

But as California's climate warmed up,

the bird song started to change.

When we move to 2014, the birds have dropped off precipitously.

Now, Bernie was picking up only a quarter of what was there before.

Hardly hear anything at all.

This was an early warning

that the forests were dangerously heating up

and worse was to come.

So, when we get to 2015, things have really changed.

We have finally come to what I call a silent spring.

There are almost no birds.

It's the first time in my life I've ever heard a silent spring.

We're just losing all of this wonderful orchestra.

Eight of the ten hottest years ever recorded in California

have been in the last decade.

But Bernie's studies show if we listen to nature,

we can hear powerful clues about the health of our wild places.

After 50 years of this work, I'm just seeing and hearing less and less.

And it's not because I'm losing my hearing.

It's because these things are going really fast,

and we've got to figure out a way to protect that.

One solution could lie in taking Bernie's approach

and supersizing it in the wildest places on the planet.

Tropical forests are home to more endangered species than anywhere else.

But each year over 20 million acres of forest are cut down,

putting animals under increasing pressure.

I think we may have found our tree.

- That one? - Yeah.

To help protect them,

conservation group Rainforest Connection is taking sound recording to another level

in a new branch of acoustic science.

Bioacoustics is the study of species through sound.

Majority of the species are vocal.

Being able to listen and understand why they're vocalizing,

it's a really amazing way of ultimately conserving them.

Bourhan Yassin and Kris Harmon

want to track Puerto Rico's noisiest forest residents,

especially one of the world's rarest birds,

the Puerto Rican parrot.

The reason that we're monitoring the parrot, it's critically endangered.

There are only a handful that are left,

so it's really important to know what is going on with them.

They plan to do this by miking up 4,000 acres

in Rio Abajo State Forest,

using a network of high-tech recorders called guardians.

The guardian device is a mobile computer in the middle of the forest.

So it has a lot of capability to not just record audio

but also understand its surrounding and analyze the audio.

There's a microphone that gets plugged in in the front of the box.

To eavesdrop on the entire forest,

the best place to position the recorders...

Incoming.

...is over 100 feet up at the top of the canopy.

Kris, can you hear me okay?

- Yeah, I've got you. No problem. - I don't think I can go any higher.

I have a beautiful view of the valley in front of me.

- We'll get started on the installation. - Awesome. Good luck.

Just doing a quick mic test on the guardian mic.

Yeah, that came through crystal clear.

- You're good. - Awesome.

I think we're good to go man.

This is the first guardian installed in Rio Abajo.

How cool is that?

No, that's perfect. Honestly, couldn't ask for better.

Each device can detect sounds from up to a mile away

and uses artificial intelligence to pick out the calls of specific animals.

The AI is running, and we have it set to pick up I think 40 different species

and automatically identify those.

So instead of any of us having to go in and look for anything

and sort of manually find the species, the model is constantly running,

and so, we'll have output really 24-7.

As well as Puerto Rico,

this technology is up and running in 35 countries,

constantly listening for the calls of over 3,000 species.

But the guardians can do something even more amazing.

They can pick out the telltale sounds of illegal logging

and send an alert to rangers on the ground.

There is no other system, that I'm aware of,

where within a handful of minutes you can detect a threat,

send a message to enforcement, and have a patrol respond to that threat.

Detecting the calls of animals and illegal logging

in dense jungle is remarkable.

But off the coast of Hawaii,

cutting-edge technology is also being used

to follow the ocean's greatest singers.

Humpback whales are the Pacific's long-distance travelers.

But to protect them, we need to know where they roam.

They're known to migrate from their Hawaiian breeding grounds

thousands of miles to their northern feeding grounds.

But where else they travel is largely a mystery.

All right. You guys, are you ready?

- We're ready. - All right.

Cool. We're ready to rock and roll here.

So excited to do this.

And marine biologist Beth Goodwin and her team

are hoping to solve this...

Oh, yeah.

...by tracking the humpbacks using their remarkable song.

This is great.

These whales are going off, they're groaning and creaking and...

You know, when I listen to these songs, I am just in awe,

but I'd like to know more.

To find out where the whales travel

means searching thousands of miles of open ocean...

...and conventional technology just won't work.

We've developed tracking devices,

tags, that you can put on the humpback whale.

But those tags, they don't last four or five months.

So they've come up with an ingenious sonic solution.

Murray, I'm taking the break off.

Going down, Europa.

A self-propelled, acoustic probe called a Wave Glider

that can travel across oceans for up to a year at a time.

A Wave Glider is a two-part vehicle that has a surface component,

and it's attached to an underwater part.

We call it the sub.

The sub has six set of wings or fins.

The float's not steering, it's literally just a bobber,

and as it bobs these wings are kind of going up and down all the time.

And it just takes the tiniest bit of ripple in the water for it to move.

What's really cool is we've attached a smart hydrophone underneath the sub

so we can download and listen where the Wave Glider is and what she's hearing.

Okay. Are you ready?

This Wave Glider, nicknamed Europa,

is heading out to search 5,000 miles of ocean between Hawaii and Mexico.

What are the odds of this ten-foot-long, autonomous vehicle intersecting a whale?

I mean, really, it's like searching for a needle in a haystack.

Ready?

- Ready. - Yup.

And the time has come...

to set it off.

And there she goes.

Wow.

We did it.

- Wow. - Have a good trip, Europa!

In five months' time,

if Europa can navigate safely back to Hawaii...

it could redefine what we know about where these ocean giants roam.

On the other side of the planet...

another pioneering acoustic project is gathering vital clues...

to help save one of the world's rarest predators.

African wild dogs.

Less than 700 packs are left in the wild and their numbers are dropping.

In recent years, their home in Southern Africa

has experienced more frequent and intense heat waves because of climate change.

Scientists believe this could be contributing to their decline...

and that's where sound can help.

If you see a wild dog let me know.

Kasim Rafiq from the University of Washington

is teaming up with conservation group Wild Entrust...

Okay. Let's go see the dogs.

...to identify the most important places wild dogs hunt and raise their pups

by tapping into their highly chatty nature.

Sound is a key way in which the animals of this area communicate.

But it's also a key way for us as researchers

to understand what's happening.

But tracking fast-moving predators

that roam over 500 square miles is no easy task.

African wild dogs are very, very hard to follow

because they move very, very fast across these landscapes

that are dotted with these massive holes

from elephants and, like, aardvarks and warthogs.

And often if you try and follow them when they're hunting...

you just drive your Land Rover straight into it.

So the team has come up with a novel approach:

miking up the dogs with a lightweight, acoustic collar.

A normal wildlife tracking collar tells us where the animals are going,

but it doesn't tell us what the animals are doing in those areas.

The acoustic part... So, it's a little box that we designed

and that fits onto the side of a normal wildlife tracking collar,

and it allows us to hear exactly what the animals are getting up to.

Using these acoustic collars,

the team will be able to monitor the pack 24-7.

But first, they need to find a healthy adult to collar.

They're probably under there.

And vet Rob Jackson and Kasim know just the individual.

Let me just ID the dog first.

Where is Jessie?

One of the pack's large males, Jessie,

will give them the best chance to eavesdrop

into the heart of wild dog family life.

- Okay, well, can we dart? - Yeah.

The anesthetic dart is harmless and will sedate him for 20 minutes.

Okay, have you got that blindfold?

Okay, you can come out, Kas.

Let's get the collar on, let's get the dart out.

It's a chance to give Jessie a health check.

The teeth gives an indication of how healthy it is.

They should be very strong to bring down their preys and stuff.

Yeah, he's moving. Perfect.

He's breathing nicely. He appears healthy.

All good.

The onboard mic starts picking up the family's most intimate calls...

closer than ever before.

A few days later,

the collar captures a key sound that the team has been hoping for.

One of my favorite vocalizations

occurs when the wild dogs are getting ready to move.

They create this weird sound that sounds like birds twittering.

And I love that for two reasons.

One, you get, like, caught up in the emotion of it.

And two, it means that something really exciting is gonna happen.

This twittering call is a sign the pack...

- Let's go. - ...is preparing to hunt.

Mike, Mike, you can follow us.

The dogs can cover up to five miles of rough ground on a hunt,

and Kasim knows he can't track them for long.

It looks like they spotted something.

Yeah, impala, impala.

I think we might lose them.

Now, the acoustic collar comes into its own.

The GPS tracks exactly where the dogs go...

and the microphone reveals key information about their behavior.

This time, a successful hunt.

Over five months, the team collects 900 hours of audio.

And by listening to the dogs around the clock,

these onboard recordings will help them better understand

how the pack's ability to hunt is being affected by rising temperatures.

The acoustic collars are gonna give us this ability

to translate exactly what the animals have been doing.

And I think that's really important because it's gonna give us insights

into how climate change is impacting the ability of these animals to survive.

And that's very, very exciting.

From the African Savannah to the polar ice caps...

the impacts of climate change are being seen and heard across the planet.

Temperatures in the Arctic are rising four times faster than anywhere else.

The loss of ice is affecting wildlife and raising sea levels.

But it's also creating another problem.

Ocean noise pollution.

As the Arctic ice cap thins and shrinks,

shipping lanes are opening up in places never possible before.

For Arctic wildlife,

the dramatic increase in ships is disastrous.

It's something that Norwegian sound recordist, Jana Winderen,

is experiencing in her work to capture the sounds of the Arctic's animals...

including its most endearing heavyweights...

walrus.

The breeding season is approaching,

and Jana is hoping to record their incredible underwater calls.

There is a knocking sound.

I can hear them really well, but I can't see it just right now.

Tick, tick, tick, tick, tick, tick, tick. Like this.

That is the courtship sound of the walrus.

Wow, this is brilliant.

She's just like... They're just over there. Look.

Walrus are masters of underwater sound.

Their courtship knocks carry for miles,

helping them find mates in this icy wilderness.

That's the first time I've seen walruses so close.

You can see like the eyes looking, you know.

It's brilliant.

But the walrus calls are increasingly being drowned out.

Yeah, I can hear the boat.

And even if I don't see the boat, I can hear it.

It's really worrying, because it's...

You know, with this shipping lane, it will separate habitats from each other.

Species that are migrating

or they're going to a particular area to feed...

They might have suddenly, like, a shipping lane right through their dinner table,

and they can't hear each other, you know?

And they can't meet each other. They can't meet a mate.

So, it's like eating dinner every day in the middle of a motorway.

Recent studies show underwater noise pollution in the Arctic

has doubled in just six years...

but we still have time to tackle it.

There is regulations that can be done in terms of how much sound the ship makes,

or what time of year you're having the traffic.

This is the mating ground and, you know,

we don't need to kind of just drive straight through it all year around.

Sound pollution is one of the more straightforward

types of pollutants to deal with.

You simply turn it off or at least turn it down.

Recordings like Jana's will help scientists identify key hot spots

that marine mammals use to broadcast their courtship calls...

helping us better protect them throughout the Arctic Ocean.

Okay, you guys good?

Okay, we're ready? Okay, here we go.

Back in the Pacific,

it's been five months since Beth and her team launched the acoustic Wave Glider.

All clear.

Now it's time to retrieve it and discover if their efforts

to track humpback whales through sound have paid off.

Right now, as of about five minutes ago,

she was off of this bay right here, about ten miles offshore.

This is our time. We're gonna go get her.

Let's do this, okay?

Europa has been traveling all the way to Mexico and back

in search for humpback whale song

in unidentified areas where people aren't expecting to hear them.

If Europa has recorded humpback song,

it could shed new light on the whales' migration routes

throughout the North Pacific.

The team just needs to find it and bring it safely aboard...

but the ocean has other plans.

Not liking that weather moving in.

The swell's picking up here a little bit. Okay, watch these...

Oh, yeah.

All eyes out. We should be right on it.

There it is. Yeah. Right there. Where the birds are.

All set for a lively recovery on the high seas.

Don't fall off up there.

All right, Murray, I've got the helm!

Oh, yeah. Okay!

Yeehaw, this is rough.

Yeah.

If the team don't get this right,

all of Europa's precious data could be lost.

I'm getting you a little closer.

- Come on! - Go, go stretch.

- One more. Yeah, here we go. - We're on!

All right.

Look at her, she's looking great!

Watch... Watch...

- Okay. Break off. - We got her.

- All right. - Nice!

So, we got Europa back.

She's got quite a few gooseneck barnacles growing on her.

A little bit of algae, but basically she looks in great shape.

As the crew head for home,

Beth can't wait to check out what Europa has been recording.

Let's download an audio file from a thousand miles offshore.

If it's captured whale song,

it'll be proof of humpbacks in the mid-Pacific.

Okay. Here we go. Let me listen.

Yeah, yeah, yeah! It's a song, that's pretty clear.

Okay. Here we go. Here's another one.

Yes, those are even louder.

- Those are even clearer. - Wow.

It's the sound that Beth and the team have waited for for so long.

Oh, my God. We heard whales. All right, you guys. That's great.

That's so great. Cool.

- Good job. - Yay.

Europa ended up being out on this mission 150 days,

and she traveled 5,000 nautical miles,

and we collected 1,700 hours of audio data.

Incredibly, Europa captured thousands of humpback recordings

which show that as well as migrating north to the feeding grounds,

the whales are also traveling between Hawaii and Mexico

in numbers never recorded before.

Not only could the whales be migrating back and forth

between Mexico and Hawaii, within the same season,

but they could be actually lingering

or having a group of them out there, traveling back and forth.

Or they could even be out there breeding and calving.

This discovery of a corridor between Hawaii and Mexico

will help us better understand and protect these ocean giants

on their travels across the North Pacific.

The fact that we heard any at all is quite phenomenal

for the technology of the Wave Glider and the hydrophone,

but also for the discovery of having them out there.

So I feel pretty pleased about that.

It's pretty impressive, really.

It's just one of the remarkable ways

we're now able to track and protect animals...

simply by listening...

to the sounds of our planet.