The Messenger

Once we believed that birds were messengers...

between humans and the supernatural world.

We would interpret the flight and songs of birds to foretell the future.

We came to understand that bird behavior heralds the change of season...

and warns us of the coming of storms.

Miners once brought tiny songbirds— canaries— down into coal mines.

When the canary stopped singing and fell from its perch,

this was a signal to the miners that their own life was in danger.

Today, once again, birds have something to tell us.

Little jumpy.

It's an old female. Oh, a repeat bird. Yay.

She's been tracked before.

She feels underweight to me. We have to make sure we weigh her.

I think birds have always inspired people.

They're beautiful to look at, they're beautiful to hear,

and because there's a mystery surrounding their disappearance.

When you consider the life of an individual migratory bird,

you can appreciate what the challenges are.

For the first time ever, we can track an individual bird...

over its entire migration journey.

This bird's about to fly down to Brazil and back.

About 15,000 kilometers.

These birds travel amazingly fast.

They'll fly from here, the Canada-US border,

down to Mexico in five days.

It's incredible.

A lot of songbirds give these little flight calls...

which we think are for air traffic control to prevent collisions.

The first step was to figure out a way to record these calls coming down.

I experimented with shotgun microphones...

and then eventually to the microphone that I built myself.

And that was one of the ways I pieced together this jigsaw puzzle...

of the identities of a lot of these calls.

This is a hearing aid microphone element.

And they're quite small.

Uh, they're very sensitive, and they have good, uh—

very good quality sound pickup.

I mount the microphone inside a two-gallon paint bucket.

I found out that this was one of the cheapest, most efficient ways...

to actually record flight calls.

A lot of the songbirds migrate at night.

The departure seems to happen about a half an hour after sunset.

And the reason we think they migrate at night,

these are small songbirds and there's larger birds that will eat them.

We now have some evidence that there's at least birds up there...

because we're hearing these call notes.

There's a few little chips happening.

And we have the radar image.

This is the last hour. That's amazing. Yeah, yeah.

The question of how long these migrations exist,

I would just say probably as long as birds existed.

Tens of thousands, maybe hundreds of thousands of years, definitely.

Aristotle thought, and it's a famous quote, obviously,

that, uh, the swallows go down in the mud in winter.

I think that's actually quite amazing that somebody stood there and said,

"Hey, these birds are moving. Where are they going?"

And really just realizing there's some major phenomenon that we don't understand.

The question of how many migratory songbirds die is an interesting one.

We can only estimate it, obviously,

because we don't know how many songbirds are out there.

Probably the best estimate is that 20 billion migrate,

so half of them don't make it back,

and that's a huge number.

On the order of 10 billion die every year,

and we find a few here and there.

We know that a few are eaten by predators, by other birds,

but where the majority goes, we have no clue.

Just a fantastic night.

Uh, lots of thrushes. Rose-breasted grosbeaks, warblers, some sparrows.

There has got to be millions of birds moving tonight.

And just this steady flow.

Just zip, zip, zip.

And it just goes on, back and forth, twice a year.

You know, these birds are tied to habitat.

They breed in certain habitats. They go to certain regions.

So if you're monitoring the population of a species,

you have this way of tuning in to the condition of the planet.

The sky is filled. The sky is filled.

But I know it's going to change.

Tonight is a special night because of this memorial to September 11.

We're in the peak of bird migration in New York City,

and that light is so powerful that it confuses birds.

And under certain conditions that can be deadly.

Couple of birds up very high in the beams.

If large numbers of birds are attracted,

starting to descend closer and closer to the light,

we are able to shut the lights off.

The thing that we worry about is that birds may collide with one another...

or with some of the structures that are around here.

The last thing that anybody wants to see at this site...

is a bunch of dead birds littering the streets.

So starting to see a little bit of a different pattern on radar.

This is the reflectivity image telling us how much is up in the atmosphere.

Definitely larger migration, more intense migration than we were thinking.

This is the Bill Evans special.

It's a pretty cool tool of the trade.

Hopefully we'll get a little more information to identify what the species are.

Birds face an increasing number of threats.

There are some major changes as the world has industrialized.

Over the past century, the level of artificial light pollution has skyrocketed.

Birds evolved in a world where they're primarily migrating at night,

orienting with the magnetic field, celestial bodies,

various other cues that they can use.

Light trumps that.

A bird— Whoa!

A very low bird there.

They are sticking around the beam quite a lot.

There are certainly enough birds up there to warrant being worried.

Hey, Susan. There's a bird on the deck.

It was flying around right at ground level.

- Around here in this area? - Yeah. It was just in this sort of zone right here.

Yeah, I think it's time to pull the plug.

Birds are down pretty low here.

We're gonna leave 'em on for five more minutes.

We have to do it now.

We're already hearing the calls drop off tremendously.

And we'll see what the next period of light holds.

It's a warbler.

They're small, so they don't get major trauma, but he's hit the window.

A friend of mine told me,

"Did you hear about birds flying into Toronto's buildings at night?"

And I was so captivated by this...

that I had to go and see if it was happening for myself,

and I've just never looked back since.

By far the most common cause of death to these birds is severe head trauma,

where the brain hemorrhaging is so significant that they will die from that impact.

There's broken bones, there's cracked beaks.

Sometimes the beaks totally fall off.

Um, there's feather damage.

All right. How many have you got?

Too many.

Now one thing that, uh, we're noticing...

is we're picking up a ton of Canada warblers, which is—

- A ton of Canada warblers? - Well, a ton for us.

I think there's well over 20 so far.

Oh, great. A species of concern. Yes.

There's little things we can do by just changing our work habits...

that can reduce this problem significantly.

How often can you say you flick a switch and a problem disappears?

You turn off lights, you're going to be saving birds lives.

Birds do not perceive glass.

What they're seeing is the reflection of the environment that they're in...

or they're seeing, uh,

what would be a clear passage to something on the other side of that transparent glass.

The more natural the environment, the greater the threat.

One of our records for daytime is over 500 birds...

over a six-hour period at just two structures.

And you can stand at the base of these structures...

and you just catch the birds as they're falling.

You can bend down and pick up a bird, and two have fallen on your back.

Oh, here's a second little guy.

They're so close to each other.

Maybe they were even flying together.

It is now illegal...

that if you knowingly are killing birds in significant numbers,

knowingly killing birds as a result of light reflecting off of your building,

you are breaking the law.

What you have to do is demonstrate due diligence.

You have to demonstrate that you are doing all you can...

to prevent this problem from occurring.

The key is treat that glass with markers,

and you will be dealing with a great deal of the problem right there.

The good days? You can stack them up really bad.

You can have 10 or 20 dead birds, one after the other,

and you find one live and that one live you get to release.

And that just completely makes the day for you. It truly does.

Songbirds are perhaps most vulnerable during migration itself.

They have no choice but to come down and land in peoples' backyards and in our parks...

where often they face a real threat of mortality...

while they're just trying to refuel and continue on their journey.

For the longest time,

we really didn't have a good estimate of the total number of birds...

that were dying due to cat predation.

When you talk to cat people, they say, "My cat doesn't kill any birds."

Well, you know, that's actually possible.

But some cats actually kill a lot of birds.

You know, one, two, three, five a week— one every day.

So we actually undertook this study that examined all of the research to date...

within the US, Canada, Europe.

We pulled together as many studies as we possibly could.

And we were quite surprised by the numbers.

We came up with a conservative estimate of 1.4 billion birds...

killed by cats per year.

Cats have been around and part of human civilization for a long time.

That said, it doesn't mean that they have been moved to places...

where they are natural components to these fragile ecosystems.

They're just not.

They are as invasive as West Nile Virus.

They're as invasive as kudzu vines or zebra mussels.

They are not natural components of the environment anywhere.

There are at least 32 species of birds...

that are known to have been caused to go extinct at the paws of cats.

Humans are ultimately the issue here.

And so, we've got to come up with some solutions.

We've got a conundrum that we've got to deal with.

We can't continue to allow cats to change the population size of wildlife.

I was just cutting birdsongs into a groove.

I took the chiffchaffs.

And, of course, a good track needs vocals,

and there's a bird who sings very good vocals.