Original artwork by  Jon McCormack .

Original artwork by Jon McCormack.

This episode was written and produced by Leila Battison.

When was the last time you stopped and really listened to birdsong? Ever wonder what they’re singing about? We chat to Kenn Kaufman and Dr. Irene Pepperberg about the extraordinary complexity to the avian arias, how they’re produced, what they mean, and how vocal acrobatics can reveal a surprising hidden intelligence.


From Zero by String Theories
Better by Airplanes
Breaking Light by Dexter Britain
Flight by Max LL
0º by Erik Kinny
The Fragile Part by AJ Hochhalter
Chrome by Steven Gutheinz
Tracking Aeroplanes by The Echelon Effect
Spring (Instrumental) by Icelanders

Twenty Thousand Hertz is produced out of the studios of Defacto Sound, and hosted by Dallas Taylor.

Follow the show on Twitter & Facebook.

Become a monthly contributor at 20k.org/donate.

If you know what this week's mystery sound is, tell us at mystery.20k.org.

Consolidate your credit card debt today and get an additional interest rate discount at lightstream.com/20k.

Try ZipRecruiter for free at ziprecruiter.com/20k.

Check out The Growth Show wherever you get your podcasts.

View Transcript ▶︎

[SFX: Birdsong Ambience]

You're listening to Twenty Thousand Hertz... I'm Dallas Taylor.

[music in]

Humans love to make noise. ...and we’ve been developing our extraordinary noise-making abilities for around a million years. [SFX: loud truck and car speed by, scares birds] We’ve graduated from simple grunts, to the intricacies of speech in thousands of languages. [SFX: Mix of people speaking different languages] Now, with the help of technology, we can make pretty much make any sound we want. [SFX: Synthetic recognisable sounds] So it’s little wonder that we consider ourselves to be the ultimate masters of sound.

[music out]

But there’s an extraordinary group of animals that might just be able to do better. Those animals are birds. Nearly half of all the birds on Earth are what’s known as songbirds. And most of them are able to produce elaborate songs, like this one… from the nightingale.

[SFX: Clear nightingale song]

Songbirds can be found in pretty much every country around the world. Wherever you go, it’s pretty likely that you’ll catch a refrain or two drifting across the air. But, if you think about it, when was the last time you actually stopped and listened to these birdsongs?

[music in]

Kenn: Since I started birding at such a young age, hearing birdsong is just a ... it's a natural part of being awake

That’s Kenn Kaufmann, a lifelong naturalist and birder. Ken’s also the author of loads of iconic field guides for identifying birds across North America.

Kenn: When I was a little kid, I was in northern Indiana in the Great Lakes area, and the neighborhood really didn't have anything in the way of rare birds or anything unusual, but even things like house sparrows [SFX: House Sparrow call] and cardinals [SFX: Cardinal call], they were just so intense. That was the thing, just birds just seemed so intensely alive, that I was fascinated by them.

[music out]

Kenn: Birds, they can make an incredible variety of sounds from extremely low-pitched sounds, [SFX: low pitched bird sound] and they can make high-pitched sounds [SFX: high pitched bird sound] beyond the range of human hearing. They really have quite a range, and they can go from harsh, to sweet, to buzzy, so all different tone qualities [SFX: complex buzzy bird sound].

The key to this extraordinary range of sounds lies in the bird’s physical anatomy.

Kenn: Humans and other mammals, we've got this organ called the larynx that's at the top of the trachea, at the top of our windpipe. And the action of the muscles and the folds around that, when air goes through the larynx, we make things like the voice, like the words that I'm saying now.

You can try it yourself. Put your fingers over your Adam’s Apple. When you speak, you can feel the vibrations from your Larynx, which comes out of your mouth as sound.

Songbirds have a larynx too, but they don’t use it for making sound. For that, they have different organ called the syrinx.

Kenn: It's at the base of the windpipe where it connects to the lungs. And at that point the windpipe, divides into two. There's two branches there, and those two collectively make up the syrinx. So each half, each of these tubes going into half the lungs, has its own set of really intricate muscles and membranes, and the way that they vibrate as the air passes through creates the bird sound.

There are a lot of similarities between the human larynx and the songbird’s syrinx. But the fact that the syrinx is placed on the two branches leading to the lungs is all-important.

Kenn: The two parts of the syrinx can actually operate independently, so a bird literally can sing two notes at once. It can sing a chord. There's a bird in New Zealand called the kokako. It's this amazing bird that goes bounding around in the rainforest. It looks bizarre. But when the kokako is singing, you can really hear the two notes being sung at once, [SFX: Kokako songs] and it's beautiful. It sounds like someone's improvising on an organ back in the forest, just slowly doing these notes, these little trills, and grace notes, and chords. And then every once in a while, it'll throw in this weird, odd sort of squawk or ugly noise just so we know it's actually a bird.

With a two-part syrinx that’s more versatile than our own voice boxes, songbirds can vocalise all sorts of sounds. For instance, here’s a crow mimicking someone saying “y’alright love?”. [SFX: Crow saying ‘Y’alright love’]

Doctor Irene Pepperberg is a professor of animal cognition and interspecies communication at Harvard. She’s working with African Grey Parrots, training them to broaden their repertoire into the realms of human speech.

Irene: They can't say the words right away. It turns out in order to produce the vocalizations, they have to control their sound source which is the syrinx, and they have to learn to control the tracheal muscles, the larynx and the glottis, the opening and closing of their beak and the tongue back and forth and up and down the way we use our tongue up and down, back and forth.

[SFX: Groucho the Parrot singing “jingle bells”]

Irene: There's lots of muscles and lots of things they have to learn to control. Just like we, I mean think about going Ah versus Ee, so they have to learn all of those.

Some words are especially hard for Irene’s birds. They might not have the right anatomy to replicate the sound faithfully, but they can usually improvise.

Irene: For something like a Pa with lips, imagine saying Pa without lips. That takes much, much longer because the bird has to actually learn how to use esophageal speech to sort of burp it.

[SFX: Parrot speech inc ‘peekaboo’, bird singing “Happy Birthday’]

[music in]

Getting your ear into the components of birdsong makes it a lot simpler to hear the differences between species, groups, and even individuals. And although there’s a huge amount of variety among the 4000 or more species of songbirds, it’s pretty clear that there are different songs for different situations.

Kenn: So a black-capped chickadee will make a certain kind of scraping sound if there's some sort of undefined danger, like a predator at a– distance.

[music out]

Kenn: [SFX: Black-capped chickadee song from :42] It'll do a chickadee-dee-dee call, and the number of dee notes at the end will increase with increasing anxiety, or the approach of a predator, and so on [SFX: extended Black-capped chickadee song].

Kenn: The black-throated green warbler is one where the male has two different kinds of songs. Onesong is mainly just for defending the territory and communicating with other males. [SFX: Black-throated warbler territory song] The other type of song is more for communicating with the female, communicating with the mate. [SFX: Black-throated warbler mate song]. So they'll use these different songs in different situations.

Even the African Grey Parrots that Irene studies have a vast repertoire of songs in the wild.

Irene: My students were in Africa for several field seasons. It's extremely hard to study these birds. They live in the canopy [SFX: Forest ambience]. They take off and you're back down on the ground. So, tracking them is extremely hard, but what we were able to figure out was that they have a huge repertoire.

[SFX: African Grey natural vocalisations]

Irene: Certain vocalization seem to be aggressive, certain ones seem to be affiliative a pair-bonded bird had specific vocalizations they use with one another to identify one another.

[music in]

Birds of the same species will tend to sing the same song, but when groups of those birds live in different regions, some interesting differences start to creep in.

Irene: There seems to be for certain parrots, we don't know if this is true for Greys, but for Amazonian parrots, there are dialects. And, if a bird leaves one flock and goes to a different flock, they have to learn a slightly different dialect.

Kenn: White-crowned sparrows just west of Hudson Bay in Canada will sing something that sounds like, I-wanna-go-swee-swee-now." [SFX: White crowned sparrow calls] It's the same pattern. You can hear them in migration, or even on the wintering grounds, occasionally doing that same song. [SFX: White crowned sparrow calls] But you could go some place over farther west in Canada and it will be a completely different pattern of songs. It'll still be some whistles, and buzzes, and trills, but they'll be arranged in a different pattern.

[SFX: White crowned sparrow calls fade out]

[music out]

It’s not just the remixing of a particular bird’s song that you can hear when you travel from place to place. Environmental noise will also shape what a bird sings.

Kenn: Birds that live along rushing streams tend to have really loud songs. So like the dipper, for example, has a really loud song so you can hear it over the sound of rushing water.

[SFX: Dipper song with rushing stream sound]

Kenn: Birds that live down in dense undergrowth often have louder and lower-pitched songs than birds that live up in the treetops where things are more open.

[SFX: Thrush-like antpitta with rustling leaves ambience]

But how exactly do these birds learn these songs to begin with?

Kenn: Their call notes, are instinctive, so they're born with those, but the songs are learned. The bird apparently has sort of a mental template for what the song is supposed to be, but if it doesn't actually hear the song, it will never learn it. So the template is important because a baby bird is gonna hear all kinds of birds in the neighborhood, and it could easily pick up the wrong language.

So, just like a human baby, the instinct to cry out is hardwired, but a bird’s song, like our speech, is learned.

Kenn: Something like a young song sparrow is sitting around listening to the male song sparrows singing in the neighborhood, and hearing that, and so it picks up the sound. [SFX: Song sparrow layered songs]. And during the first summer after it hatches, it may not make much sound. In the fall, it may begin doing these weird little whisper songs that are very disorganized [SFX: song sparrow song broken up]. But then the following spring, it will go rapidly through this sequence where it does these really disorganized songs [SFX: rapid practicing song with errors]. Then it starts putting the elements together, and eventually it's doing a song very much like what it had heard the previous summer [SFX: clear accurate song sparrow song].

On the other hand, there are birds whose songs, as complicated as they might be, are completely innate. One such bird is the flycatcher.

Kenn: People have tried the experiment of raising these birds in the laboratory and not letting them hear any natural sound of their own species, but even so they grow up to sing the right song just perfectly. [SFX: flycatcher song] If you try that with something like a song sparrow, it won't develop the right song. But the flycatchers, they've got it as an instinct, and so it's the main way that they recognize their own species. It's not visual. It's entirely based on these songs.

Even in the relatively short time that towns and cities have been spreading across the countryside, birds have stayed one step ahead.

Kenn: Studies have found that birds are singing differently in urban areas. In some cases they sing more loudly, or they'll sing in a lower pitch for it to carry better through the surrounding sounds.

[SFX: Loud urban song example with urban ambience]

So with all these noises and competing songs it’s amazing that birds can learn the right melodies.

But birds are not just singing for fun - they are communicating with each other. And, sometimes they can communicate with us too. Literally, in english. We’ll meet an extraordinary bird who learned to communicate at a new level and changed animal science forever. Thats coming up after the break.


[SFX: Noisy layered birdsong ambience and natural sounds]

To human ears, birds songs are beautiful background noise. But some birds are so adept to learning new sounds, they can perform sounds from entirely different species.

Mockingbirds are known for mimicking the sounds of other birds and animals around them. Their night-time medley might include the songs of [SFX: smooth medley of birdsongs] blackbirds, cardinals, house wrens, hawks, and even the sound of frogs.

In Australia, the Lyre bird takes mimicry to the next level. Here’s an alarm, a chainsaw, and camera shutter. Again, these sounds are coming from a bird.

[SFX: Lyre bird alarm, chainsaw, camera shutter]

The Lyre Bird has one of the most complex syrinxes of all songbirds, which means it doesn’t just replicate other birdsong and animal voices, but pretty much any noise it hears.

[music in]

Irene: Birds are known as vocal learners. There aren't that many creatures in the world that are vocal learners. Mostly it's humans, dolphins, bats, sea lions...

Vocal learners are animals that are able to hear a sound, assimilate it, and figure out how to produce it themselves. It turns out it’s quite a rare skill, that could hint at an underestimated intelligence.

Certain birds like the Lyrebird and the African Grey Parrot continue to learn new sounds throughout their entire lifetime.

Irene: In humans there are seven brain areas that are responsible for the ability to learn vocalizations. We know that they are seven of these areas in the avian brain on the songbirds that learn. There are very similar areas in the parrots that learn. We know there's even an extra area in the parrot brain, a sort of a shell that allows them to not just learn vocalizations but learn vocalizations that are not specific to their species.

[music out]

At the interspecies communication lab at Harvard, the birds are taught to associate sounds with objects. Over time they can demonstrate vocabulary, and an understanding of the world around them. For thirty years, the star of Dr Pepperberg’s lab was a bird named Alex.

[music in]

Irene: Alex was very special not because he was an Einstein of a parrot, but because he was an only bird for 15 years and he had this small army of students working with him and treating him like a toddler and talking to him constantly.

Irene: He became my closest colleague. I cared for him the way you care for a colleague. I mean you ask after a colleague's health. You commiserate with them. You care about them in ways, but you have a different relationship with them than you would with a pet or with a significant other or with a child. He was my collaborator and colleague.

With the attention of a team of researchers, Alex learned hundreds of words, as well as their meanings, and was soon amazing his human colleagues with his linguistic creativity.

[music out]

[SFX: Alex-Irene interactions inc Alex: “I want banana” , “I want corn, soft corn”, “Wanna go eat dinner”]

Irene: For example we were training Alex on apple, and the “Pa” sound is quite difficult and he knew cherry and banana and he just started calling it banary, like it tastes a little bit like a banana, looks like a big cherry..

[SFX: Alex: ‘banarry’ - Irene: “go see in your bowl if you’ve got Banarry’ - Alex: ‘Do you want bannary’]

Irene: Sometimes he would spontaneously come up with labels, he came up with banacker, banana cracker. We gave him dried banana chips, he hated them, so that was the end of banacker.

[music in]

With a solid vocabulary in place, Irene could start to test Alex’s cognition with some basic tasks.

Irene: We were trying to get comprehension of numbers and we'd give him a tray with numbers of blocks, of different colors and slightly different sizes, so there would be, say, six blue, three yellow and two purple and I would say, "What color is six?" and they'd be all mixed up and he had to find the size on the tray and say, "Oh, those were that color”.

[music out]

[SFX: Irene: ‘Alex, what matter’ / Alex: “wool” / Irene: ‘That's right! How many?’ / Alex: two / Irene: ‘That's right!)]

It’s the sort of activity you’d use to test small children on their counting abilities. But, just like working with small children, things didn’t always go as planned.

Irene: When we did this study, it was very boring because he knew these objects, he knew these colors, he knew these numbers.

Irene: So I come in one day and I have three, four and six sets on the tray and I say, "What color three?" and he looks at me and he goes, "Five," and I go, "No, Alex. What color is three?" and he repeats, "Five," and I'm looking, "Okay, there is no set of five on the tray." He's not throwing things on the floor. He is not turning his back and preening. He is not saying the wrong color. I ask him again and again, "Five." So I said, "Okay, smarty. What color five?" thinking, "All right, you want to talk about five. I don't know what you're going to say." He looks at me and he goes, "None." There are obviously no five things on the tray. Basically, not only had he shown the zero-like concept, but he had manipulated me into asking the question that he wanted to answer.

[SFX: Alex-Irene interaction: “You’re a good boy” “Can I go back?” “No sweetie, you can’t go back yet.” “Want some water” “Alright, you want some water or are you just asking to interrupt? Are you asking to interrupt?”]

Whether he was cooperating or not, Alex’s work on these kinds of tests allowed researchers to begin to compare his and other parrots’ intelligence levels to those of humans.

Irene: In terms of their vocalization abilities, they never got beyond 1-1/2 or 2-year-old child. I mean we never had complex sentences, but in terms of cognitive processes, some of the task’s we did with Alex showed he was at level of a 4-year-old child.

[SFX: Alex-Irene interactions: “Hey look, can you tell me, on the tray how many green block?” “Two” “What color bigger?” “Green”]

Irene: Alex was able to infer the cardinality of a number its place on the number line the way young children could do and apes have not yet been able to do that.

[SFX: Irene: “how many corners? What shape?” Alex: “Four...Corner”]

Alex’s curiosity and his high performance in cognitive tests pointed at an incredible intelligence that was a total surprise to scientists.

Irene: They thought that birds are at best mindless mimics, that they were completely inferior to mammals and absolutely inferior to primates. Basically, “bird brain” was a pejorative term - and here I had this bird that was doing the same types of tasks as the primates. This was a huge breakthrough. I mean a brain the size of a shelled walnut literally, an animal separated evolutionarily from humans by 300 million years and doing the same types of tasks as the non-human primates. That was a shock.

[music in]

Having revolutionised the way that we look at birds - not only in terms of their vocal versatility, but also their underappreciated intelligence, Irene and Alex were looking forward to a productive future together.

Until, disaster struck.

Irene: I was doing email which I always do over breakfast and had just learned that we had gotten a lovely grant so I was very excited. I treated myself to a second cup of coffee to celebrate and I came back with that second cup of coffee and there was an email and it said, "Sad news." I initially didn't think anything of it.

Irene: Then I opened it up and it told me that there was an ex-parrot in the lab and it was Alex's cage and I just completely freaked out. According to my veterinarian, it was a heart arrhythmia which is something that just happens.

Everyone had expected Alex’s life, and his career, to go on for decades more. His death was a loss that was felt across the scientific community.

Irene: He had an obituary in The Economist, The New York Times, and Time Magazine. The emails were pouring in. My phone was ringing. My lab manager's phone was ringing. The lab phone was ringing. The emails, we couldn't even keep up with the emails.

Alex was 31 years old when he passed. He was expected to live another 15-20 years. His last words were to Irene the night before. He said, “you be good, see you tomorrow, I love you”.

[music out]

[music in]

Irene: I'm fascinated with the idea of understanding how other creatures interpret our world and how they function in our world and helping other people understand the beauty of recognizing other intelligences.

On the surface, birdsong is simple. It’s a pleasing wash of sound that happens in the background. But if you stop and listen, you might find a deeper meaning.

[SFX: Birdsong ambience building]

Kenn: I would like to encourage people to go out and listen to birds, to just go out and make the conscious effort to focus, and concentrate, and just listen to the birds. Even if you don't know what kind they are, I think you'll be amazed at the variety of sounds that you hear. And if you start to pay more attention, it really will brighten up your world.

[music out / birdsong continues]

Twenty Thousand Hertz is produced out of the studios Defacto Sound, a sound design team dedicated to making television, film and games sound incredible. Find out more at defactosound.com.

This episode was written and produced by Leila Battison, and me Dallas Taylor. With help from Sam Schneble. It was sound designed and mixed by Nick Spradlin.

Thanks to Kenn Kaufman and Dr. Irene Pepperberg. You can find out more about the work Irene is doing at Alex Foundation dot org.

And if you want to take Kenn up on his advice to go out and listen to birdsong in YOUR neighborhood - which I really, really hope you do - then you should pick up one of his beautifully illustrated field guides, you can find that at kaufmanfieldguides dot com. That’s KAUFMAN - fieldguides dot com. You can also find them on Amazon or in most places you buy books.

All of the human-made music in this episode was from our friends at musicbed. Check them out at musicbed.com.

Finally, if you have a comment, episode, or just want to tell us what your favorite bird song is… reach out on twitter, facebook, or by writing hi at 20k dot org.

Thanks for listening.

[birdsong out]

Recent Episodes