Bird Sounds Decoded

[Slide text: Nathan Pieplow, Bird Sounds Decoded, Earbirding.com; Photo: Male common yellowthroat singing]

[Matt] Hello everyone, thanks. I’d like to thank everybody for coming tonight. I get the great chance to introduce tonight’s speaker. I’m Matt Young, I work in Macaulay Library, for some of you that don’t, a lot of you know me, but not everybody.

But anyway Nathan grew up in Sioux Falls, South Dakota. I always like to tell all the, you know it’s always interesting to me the journey people take to come up with and accomplish the goal or a task of writing a Peterson Field Guide. It’s pretty ambitious, I’d say.

So he grew up Sioux Falls, South Dakota, his grandmother was the spark behind his birding interest. In 1998 he actually moved to the east, to Massachusetts, and worked on his undergraduate degree in Russian literature and language at Williams College, and actually spent a year in Russia, you know studying the language and the literature there. And shortly thereafter he finished the degree, you know moved on, got his degree in education, a master’s degree in education at Oregon University.

But then he, in 2001, he moved to Colorado, and that’s where things really started, the the bird interest seemed to really grab hold, and he developed this really pivotal, I’d say, relationship with a colleague that unfortunately couldn’t be here tonight, Andrew Spencer. And the two of them started, you know, traveling the country and traveling the world, and Nathan then dove into bird sounds. And started to study the differences at the very, you know, minute level, differences in bird sounds.

Now, about 2008 is when I first met Nathan via email, and it was an exchange as some of you know or don’t know, not surprisingly about crossbills, I’m a bit of a fanatic about crossbills. And they’re very interesting, you know, vocally cuz there’s a lot of different call types. And what’s amazing to me about accomplishing a book like this, in a, you know, putting together a Peterson Field Guide to Bird Sounds, is that I only dove, I only dove into really at that minor level, crossbills.

He’s done that for all the species across North America, including a lot of different complexes. Even across the world, so so I don’t go on anymore, I’d like to introduce Nathan Pieplow.

[Applause]

[Nathan] Thank you, can everybody hear me fine? I’m gonna just walk down the middle of the room a lot, and kind of be in the middle here, cuz I’d rather be out here than up there. I’m a teacher so I like to treat this like a classroom, if that’s all right with you.

[Bob] If you’ve got a microphone there, I don’t think it’s on.

[Nathan] No see, so I’ve got a microphone, and I didn’t think it was on either, but it’s for the web actually, and not for you guys, so. They told me I could get a second microphone if I wanted to be amplified in this room, I said I think it’ll be all right. This is Bob McGuire, for those of you who don’t know. How many of you, how many of you went to Bob’s talk on his trip to Russia a little while ago, yes?

[Cheering]

So I was on that trip with Bob and that was where I got to use my Russian language for the first time in 20 years, [laughter] going back to Russia for the first time. So, great to see Bob again, great to see all of you, a lot of familiar faces here, and yeah, and that, and thank you, Matt, by the way, for the best introduction I’ve ever had. I almost, almost started stealing my thunder there a little bit at the end.

So yeah, so I’m here to talk about bird sounds tonight, and I like to talk about the book that I wrote, we’ll talk a little bit about that, and we’ll also talk a little bit about individual birds and what they’re actually saying. Because that’s really what we’re ultimately interested in.

[Slide text: The birds are always telling us Who they are and what they’re doing]

I like to say that the birds are always, all around us, all the time, telling us who they are and what they’re doing, but the problem is we don’t all speak bird.

[Photo: Red-winged blackbird male; Audio: Red-winged blackbird male singing]

So that red-winged blackbird right there just told you that he’s a red-winged blackbird. He also told you that he’s a male red-winged blackbird.

[Photo: Red-winged blackbird female; Audio: Red-winged blackbird female vocalizing]

And that red-winged blackbird just told you that she’s a female, and she also told you a few other things, which we’ll get into later tonight. We’ll get into the language of red-winged blackbirds a little bit.

[Slide text: We can learn their language]

Sometimes birds have particular words that they say that mean particular things, and we can actually learn what they’re saying.

[Slide text: “Danger!” Photo: Cliff swallow in flight; Audio: Cliff swallow alarm call]

My goal is to try and translate whenever possible, so if you, this is a cliff swallow. Those of you who know this species, if you get too close to their nests, this is the sound you’re gonna hear. That’s the cliff swallow saying “danger,” that’s the cliff swallow alarm call that they give when somebody gets too close to their nest.

[Slide text: “I’ve found food!” Photo: A second cliff swallow in flight; Audio: Cliff swallow calling]

But cliff swallows have a number of different sounds. They actually have a particularly cool sound that has a particularly cool meaning, that means “I’ve found food.” This sound they only give on cool, cloudy days, when it’s about 50 degrees, and it’s overcast or drizzling. Because on cool, cloudy days it is hard for cliff swallows to find food. Because the flying insects that they eat aren’t as active when it’s cold, aren’t as active when it’s wet, so it becomes a tough day to be a cliff swallow.

And what we’ve, researchers discovered is that on those days if one of the cliff swallows in the colony finds a swarm of flying insects, on a cool, cloudy day, they will give this call, and it will recruit the rest of the flock to come as quickly as possible and forage on the, that flock before it disappears. On that, on that, it’s not a flock right, of insects, a swarm of insects before it disappears. As far as we know, cliff swallows are the only species that does this. We don’t know of any other species of swallow or any other bird that has a food finding call quite like this.

It’s likely I would say that some related swallows probably have calls like this, but you’ll be surprised when you start studying bird sounds how little we actually know about the language of the birds. It takes a lot of field research to try to understand exactly what the birds are saying, and we’ve only done that for a few species, which is one of the reasons why I’m only going to be talking about a few species tonight [laughter] because we only know a little bit, and I’ll be sharing with you a few things that we do know.

[Slide text: A dictionary for the language of the birds; Photo: Cover of the Peterson Field Guide to Bird Sounds of Eastern North America with a bird in silhouette against the sunset singing]

So my goal was to write a dictionary for the language of the birds, at least those words that we already know, things that we already can do. This is the book that I published last spring, with the help of the Macaulay Library. I, they were a partner on this. And you’ll see a lot of the work here that was done by good people at Cornell.

The book allows you to do a bunch of cool things. Obviously the first thing that it allows you to do is find out what a particular bird sounds like. If you’ve got a bird in mind and you want to know what sounds that bird makes you can turn to that page in the book, just like any field guide.

[Image: Page of the book on the northern mockingbird, showing small drawings of mockingbirds, a range map, spectrograms of various calls, and information about them]

And you’ll see there’s a northern mockingbird, there’s all the sounds that a northern mockingbird makes. We’re drawing the sounds as spectrograms, so it’s a little bit like reading music. Same basic principle, it reads from left to right, the high notes are the top, the low notes are at the bottom. Takes a little bit to learn what those shapes mean, but you can quickly see that the northern mockingbird makes basically six different kinds of sounds.

[Image: Zoomed in view of northern mockingbird typical song spectrogram and information, with “50-200 song phrases” highlighted]

And then if you zoom in the book tells you a little bit more about the cool things that we know from the research about northern mockingbirds and their sounds. For example, each individual northern mockingbird knows between 50 and 200 different phrases with which he makes up his long and complicated song.

Interestingly, each individual northern mockingbirds might not know the same 50 to 200 phrases as the next northern mockingbird. They don’t necessarily share a vocabulary from one bird to the next, which raises a fine question. How do they talk to each other if they don’t have any sounds in common? If they don’t, if they if they don’t have any words in common in their language? In the case of northern mockingbird they famously are also imitating other species, and they’re imitating environmental sounds, they’ll imitate cell phones and car alarms, and other things that they hear.

And they’re one of the few birds that we know that can learn new sounds throughout their life. So they’re constantly probably learning new sounds, they’re constantly innovating, but interestingly we call it, some people call it mimicry when a mockingbird imitates another bird, but biologists would prefer that we not use that term for mockingbirds. Because in biology mimicry has a particular function, a particular definition. It’s when one species is trying to be mistaken for another species. For example, when a non-venomous butterfly is trying to be mistaken for a poisonous butterfly so that the birds don’t eat it, that’s mimicry.

When a mockingbird is imitating the sound of the Carolina wren we don’t a hundred percent for sure know exactly why they are imitating the sound of a Carolina wren, but we know that it’s not because they want to be mistaken for a Carolina wren. They do not want to get attacked by all the angry Carolina wrens in the neighborhood, and they do not want to be ignored by all the mockingbirds in the neighborhood.

So every time they open their mouths one of the things that they are saying is “I am a mockingbird” even though they’re doing it with words from other species’ languages and other sounds, they are saying to the world “I am a mockingbird” and they’re doing it by the pattern of the sounds that they’re delivering.

So if you’ve ever listened to a mockingbird you’ve noticed that they do one thing for a while and then they switch to something else so it’s like AAA BBB BBB BBBB CCC CCC CCC DDD DDD, that’s their pattern. And that’s how we recognize them. And that’s how they recognize each other. And that’s how the Carolina wrens realize that it’s not a, it’s not a Carolina wren, it’s a mockingbird imitating them, that’s how we realize it.

We’ll talk more a little bit about this because we have to get out of the idea sometimes when we’re listening to bird sounds, that the individual words have the meaning. Sometimes it’s the grammar that actually carries the meaning, and I’ll give you a better example later on.

[Slide text: Bird Academy, Peterson Field Guide to Bird Sounds: Explore the Companion Sound Library- Listen to all the sounds in the book—plus thousands more bonus recordings, petersonbirdsounds.com]

In addition to my book, there is a, there’s a website where we have put up all of the sounds that accompany the book. It is hosted right here at Cornell by the Bird Academy. It runs on the same hardware as All About Birds and eBird. And if you go to petersonbirdsounds.com you can enter a species name, type in northern mockingbird,

[Image: Search of northern mockingbird on petersonbirdsounds.com showing a variety of mockingbird sounds]

click on it and you can see all of the different sounds of northern mockingbird. I tried to get three examples of every sound for every species. I didn’t quite make it, but I got close. So right now for the eastern volume of the field guide there are about 5,400 bird sounds up here in this collection, and if I do say so myself it’s the most complete and best curated collection of bird sounds for North America.

[Image: Spectrogram of northern mockingbird song from petersonbirdsounds.com]

And if you click on one of those sounds you can, it’ll pull up just like it does on eBird, and you can watch the spectrogram scroll as you listen to the sound. Really really nice thing.

[Slide text: Compare similar-sounding species; Image: Cover of the Peterson Field Guide to Bird Sounds of Eastern North America]

Another thing that my book allows you to do is to compare similar-sounding species.

[Image: Carolina wren page of Peterson Field Guide to Bird Sounds of Eastern North America, showing a drawing, range map, information, and spectrograms of songs]

So for example, a Carolina wren, there’s a bunch of other things that can sound like a Carolina wren. If you go to the Carolina wren sound you see the, down there there’s a thing that says page 557, page 556. That’s the index numbers for all the similar species.

[Image: Index from book highlighting Carolina wren sounds]

If you go back to the back of the book, there’s a visual index. And it shows all the different types of sounds. Carolina wrens give two different kinds of sounds primarily. They’ll do a two syllable word repeated. Like purdee purdee purdee purdee or they’ll do a three syllable word, repeated like teakettle teakettle teakettle teakettle.

So if you hear one of those two patterns you can go to the back of the book, and you can look up, down on the lower left, all the things that sound like a yellowthroat that have a three, three syllable sound repeated. Or all the things that do a two syllable sound repeated.

You can see all the birds in the guide, in the region, that sing with a similar pattern. So that if you hear something that sounds like a Carolina wren, you’re not sure if it is, you can go and see what else might sound like that. And that that will be your guide to the 5500 sound files online. So you don’t have to listen to them all, you can just listen to the ones that might have a chance of being the one you’re listening to.

[Image: Whistled Couplet Series page of index]

[Slide text: Learn a standard vocabulary for sounds; Image: Cover of the Peterson Field Guide to Bird Sounds of Eastern North America]

Another thing I tried very hard to do in my book was to work on a standard vocabulary for sounds. We have a standard vocabulary for birds’ appearance. We all agree on the names of the colors. We all agree on the names of patterns. We know the difference between a spot and a stripe. We all agree on the names of the parts of the bird. And there’s a diagram at the beginning of every field guide that labels all the parts of the bird for beginners.

We don’t necessarily have agreement on the names for the different kinds of sounds. So what I wanted to do was start to establish some agreement. A systematic way of describing bird sounds, so that we could actually index them, so we could actually all have the same words for the same things.

Up until now, memorization was the only way to get good at identifying bird sounds. Everybody I’ve ever met who is really really good at identifying birds by ear, they’ve done it by memorizing an awful lot of sounds. It’s great, if it works for you. I personally have a really terrible memory. A really terrible auditory memory in particular.

[Slide text: Memorization was the only way, Description was subjective- Up Until Now…]

I’ve told a lot of people, a lot of people assume I’ve written a field guide to bird sounds, so I must be really good at identifying bird sounds. The truth is I’m not that great at identifying bird sounds, and that’s why I wrote a field guide. Because I need it. Because I wanted to put in that book all the information that I couldn’t keep in my head. That’s what books are for, they’re for holding information that we can’t fit in our heads.

Up until now memorization was the only way to get good at bird sounds, and all descriptions were subjective. Everybody had their own words for different kinds of sounds, how they made us feel, what they reminded us of. But now we can do things better.

[Slide text: We can visualize the sound Now…; Image: Bird song spectrogram; Audio: Bird song]

And the key is to visualize the sound, using that thing I talked about earlier called the spectrogram. A spectrogram is a graph of the sound, computer generated, and it shows the frequency against time. It takes a little bit of practice to learn how to read them. It’s a little bit like reading music. But the spectrogram is the sound.

[Image: Page from the Introduction of the Peterson Field Guide to Bird Sounds of Eastern North America, titled Visualizing Sound]

The beginning of my book explains how to read spectrograms, there’s a whole, like 20 page chapter on how to read spectrograms.

[Image: Additional pages from the Introduction of the Peterson Field Guide to Bird Sounds of Eastern North America, titled The four basic patterns of repetition and speed]

Leads you through a series of lessons, which you can learn what you’re doing. And once you have an idea of how to visualize sounds, it changes everything.

[Slide text: The spectrogram is the sound, what looks similar sounds similar, what sounds similar looks similar]

First thing to remember is that the spectrogram is the sound. All the details that your ear can hear are up there in that picture. And everything that’s up there in that picture, what’s up there in that picture is stuff that your ear can hear. That means that what looks similar sounds similar, two similar spectrograms are gonna have a similar sound, and what sounds similar looks similar, so two things that sound alike, they’re gonna have similar looking spectrograms.

And that’s key because that means we could learn the shape of a sound.

[Slide text: We could learn the shape of a sound: read the sound of a spectrogram, picture the spectrogram of a sound]

Every sound has its own shape. If we can get good at learning the shapes of sounds, that means we can read a spectrogram. We can look at that picture, and we can get an idea of what it’s gonna sound like. And conversely, it means we could picture the spectrogram of a sound, we can hear sound and figure out what it’s going to look like. If we can do that, then for the first time we could look up sounds we don’t know.

[Slide text: Look up a sound you don’t know; Image: Cover of the Peterson Field Guide to Bird Sounds of Eastern North America]

The same way that we would look up a word we don’t know in the dictionary. In order to be able to look up a word you don’t know in the dictionary you have to be able to spell it, you have to be able to sound it out. And if you can learn how to sound out, spell out a bird sound in pictures, then you can use the back of my book to look up a sound that you’re hearing that you’ve never heard before in the United States.

[Slide text: What did you hear? A single note by itself, or repeated after a pause; The same note repeated without a significant pause; A phrase of 2-3 syllables by itself, or repeated after a pause; The same phrase repeated without a significant pause; Different short notes, series, or phrases separated by pauses; A complex song of more than 3 syllables, less than 4 seconds; A long complex song at least 4 seconds without a significant pause; Audio: Examples of each song type]

At the very back of the book inside two front, inside back cover pages, there’s a quick index that breaks all the sounds into seven simple groups, and we’ll, I’ll ask you to listen to a few of these patterns so that you can figure out how we would break sounds down into these seven simple groups.

So the first group is a single note, that’s an easy one, right. Are you hearing just a single note by itself or repeat it after a pause? Because that’s one category of sound, it’s just the single note.

Or are you hearing the same note repeated? We would call that a trill, or you can call that a series, but that was the same note repeated a whole bunch of times in a row.

Right there, so you have to get start, asking yourself am I hearing the same thing over and over again or on my hearing different different notes?

Are you hearing a phrase of two or three syllables by itself or repeated after a pause? So that’s like this one, two syllables. Raise your hand if you recognize that bird. A lot of you know, a lot of you recognized that, that’s which one? Bobwhite saying his name, right there.

Some birds have the same phrase repeated over and over again. There’s your Carolina wren, right, with that three syllable word being repeated over and over again.

Some birds sing different short notes, series, or phrases separated by pauses. So they’ll say something, and then they’ll say something else, and then they’ll say something else, and then they’ll say something else.

So when they keep changing the word that they’re saying, that’s actually a field mark, that’s actually an important thing to listen to. And vireos are in that category, where they’re frequently doing that. A lot of flycatchers do things like that.

Some birds sing complicated songs with a whole bunch of things going on at once. So that’s its own category, right, the complicated song. And some birds, that’s a complicated song of less than four seconds. Some birds just never stop singing. And that was not the whole song, I just stopped the recording so we could get on with life.

How many of you recognized that bird? Anybody know which bird that was? That was a barn swallow singing, for those of you who didn’t catch it. And you can always catch the barn swallow singing because they got that nice little musical warble, and then they throw in that weird ticking trill, like this staticky sound in the middle. What did you say?

Yeah, yeah a lot of, actually all the swallows, or many of them will do that as well. The cliff swallows are even clickier than the barn swallows, more clicks than music in the in the cliff swallow song. Interestingly the researchers wanted to know a few years ago how the birds could sing, some birds could sing so long, without ever seeming to take a break, or take a breath.

And they were particularly interested in Eurasian skylarks which sing on the wing for 20, 30, 40 minutes at a time without ever seeming to ever stop. And they wondered how are the birds getting enough oxygen to keep their muscles going, and also keep this song going?

And there were a couple of hypotheses, one is that there, one one idea was that that they might actually have a circular airway type thing going, like in through the nose, out through the mouth continually. Another one was that they thought that maybe the birds were taking mini breaths in between each note, so not filling their lungs but just getting enough to essentially, to get the next note out, right.

And it, they tested this hypothesis by inventing these pressure sensors that are so small that they can be inserted into the throat of a singing bird in the laboratory. And it has to be so small that the bird’s not bothered because then it has to sing, but then they can actually measure whether the air is coming in or going out at any given second of the song.

And what they found is that it’s actually the the mini breaths, that’s actually the correct hypothesis. So they, in between each note they’re they’re taking a little quick breath in, but they don’t have enough time to take a full breath. So they just get enough to get the next note out, and just get enough to take the next flap, and just get enough to get the next note out, continually, over and over again for like 20 minutes.

[Image: Inside back cover of the Peterson Field Guide to Bird Sounds of Eastern North America, titled What Did You Hear?]

Alright, so there’s the inside back cover the book with that patterning.

[Slide text: Visualize with a spectrogram app, iPhone: Spectrumview (freemium), Android: Spectralpro Analyzer $4.49; Images: Spectrogram, Carolina wren and Kentucky warbler pages from the book showing spectrograms of their songs]

And here’s one of the really cool things that we can do now, is that we have apps that we can put on our phones, and they will make spectrograms for us. Of everything that the phone hears, everything that comes into the the phone’s microphone. And so if you get one of these two apps, these are the two best ones I’ve found.

For iPhone it’s called Spectrumview, and that’s a freemium type version, which means that you can download the free version, you can pay to upgrade to the premium version if you want. But in the case of the iPhone this Spectrumview app, the free version actually does everything that you need for to do this for birds, and the premium does, adds other features that are not particularly helpful for birds.

On Android it’s this Spectralpro Analyzer, and there you do need the pro version. You can also buy a, get a, get a free version of this, but you really need the pro version, which is $4.49 last time I checked, and, to get the features that you want for for birds.

If you download one of these apps, and you you have to kind of tweak the settings so that they get useful for bird sounds, but if you tweak the settings properly, then it’ll show you this real time scrolling spectrogram of everything that the phone hears. So if you start speaking you’ll see the spectrogram of your own voice. If a bird starts singing you’ll see the spectrogram of the bird sound. If a car drives by you’ll see this big smear of noise you know, so.

Because you’re working with your phone, and your phone doesn’t have a particularly good microphone in it, you really need birds to be loud and close for this to really to them, for them to really show up clearly on here. But if you get a nice loud, close bird it’ll generate a picture just like that one of the bird sound, and then you can stop it, freeze it, and you have taken a picture of the sound. And then you can look it up in the book.

And in in both cases you can save the pictures for later. And in, the iPhone app is really nice because it records the sound at the same time that it records the picture of the sound. So you can record the sound for later and also the the spectrogram for later. Unfortunately the Android app does not record the sounds at the same time, it just does the pictures. So you need an another phone or something to get that.

But that’s really nice because then you don’t have, it’s a nice shortcut. You don’t have to spend all the time to learn how to visualize sounds. You’ve got a phone that’ll do it for you, and you can take that shape. And because we’re all more visual than we are auditory, then we can actually start to compare, well is it more like this or is it more like that?

[Slide text: Learn what birds are saying; Image: Cover of the Peterson Field Guide to Bird Sounds of Eastern North America]

But I think the the piece that I enjoy the most, and the piece that most people enjoy the most, is using the book to try to figure out the language of the birds. What are they actually saying? What are they actually doing? What are they actually thinking?

So I promised you a little bit more information about some of these birds, so let’s talk about red-winged blackbirds.

[Slide text: What birds are saying; Images: Red-winged blackbird male and female saying, “I love you!”; Audio: Red-winged blackbird male and female duet]

When they sing together like that, the male and the female, when they duet, they are saying to each other “I love you,” they are strengthening the pair bond. So you can tell that this is a mated pair by the way the male sings first, and then halfway through his song the female starts singing, and then she finishes, but, after he finishes, right. So so he starts, and then just about a second later she starts, and they overlap in the middle and it’s a synchronized performance.

They’re not always together like this when they’re singing. The female might be down in the reeds, down near the nest, she might be out of sight. They might be you know 20 yards apart, or 30 yards apart, but they’ll do this as a pair bonding mechanism. They don’t always do it. Sometimes the male sings, sometimes the female sings, they’ll sing separately, but when they sing together, this is particularly useful for those of you who do atlas work, and bird breeding, bird atlas work, when they sing together, that’s a mated pair. And you can tell even if they’re apart in the marsh, even if both of them are not necessarily visible, you can tell that that’s a pair.

And interestingly, you’ve probably heard that a million times, and never quite realized what was going on. Because if you’re if you’re near a marsh with red-winged blackbirds you hear this constantly. And it just sounds like two birds kind of singing in the marsh, but they’re actually communicating with each other. They’re not just communicating with each other, they’re also communicating with all the other blackbirds in the marsh.

[Slide text: What birds are saying; Images: Red-winged blackbird male and female saying, “I’m taken!”; Audio: Red-winged blackbird male and female duet]

And they’re saying we are a pair, and this territory is occupied by a mated pair. So if you’re a female, the females are territorial against other females, the males are territorial against other males. Neither of them wants another bird coming in to steal their mate. And so this is this is not just an “I love you” thing, it’s also an advertisement to the rest of the marsh saying “we’re together, don’t come and try to take away my partner.”

The exact same thing, where the male starts singing and then the female does this rattle, starting halfway through, happens in several members of this family. Meadowlarks, eastern and western meadowlarks, both do this, brown-headed cowbirds do this all the time. Where the male gives that liquid kind of whistle, and then the female has that rattle. And she’ll start, even though that male song only lasts about one second, she’ll start about half second in, and then she’ll finish it out. Same exact thing. Also Carolina wrens will do something similar, the female has a rattle call she’ll sometimes do during the male’s song. A bunch of bunch of birds do something similar to this.

[Slide text: What birds are saying; Image: Red-winged blackbird male in flight saying, “Honey, I’m heading out for a bit!”; Audio: Red-winged blackbird male flight song]

That was a very long-winded way of saying “honey I’m headed out for a bit.” That, what you heard earlier was the typical song of the male red-winged blackbird, the one we’re mostly familiar with conk-a-reeee, but male red-winged blackbirds have this other song which is called the flight song, because it’s usually performed in flight. And it’s this long, weird series of call notes strung together in series. And each individual male has his own version that’s slightly different from all the other males.

Typically they give it when they are in flight, and typically they give it when they are leaving the nest site, I’m heading out of the marsh. Sometimes they’ll give it when they’re coming back, but not always. They won’t give it every time they leave, and they won’t, they’ll give it even fewer times when they come back.

As far as we know, this is a guess on the part of the researchers, but as far as we know that the best reason to for him to do that is that he’s signaling to his mate that he’s leaving the territory, and that it’s her responsibility to hold down the fort while he’s gone. That’s the, that’s our best guess on why they do that. We don’t know why they don’t do it every time, we don’t know, do it, we don’t know why they do it sometimes when they come back but more often when they leave.

But that’s a very interesting, complex sound that we’ll call a song from the male red-winged blackbird. Now the female red-winged blackbird also has more than one kind of song.

[Slide text: What birds are saying; Image: Red-winged blackbird female saying, “I love you!” and “I’m taken!”; Audio: Red-winged blackbird female courtship song]

We heard this one earlier this is the “I’m taken” slash “I love you” song, the courtship song, right there. But she also has a burier version of her song, a harsher version of her song, that she uses against other female red-winged blackbirds when they start to get into her territory.

[Slide text: What birds are saying; Image: Red-winged blackbird female saying, “Get out of my territory!”; Audio: Red-winged blackbird female territorial song]

And there’s a whole bunch of intermediate songs. A lot of times they’ll start like the courtship song, and then end like the the territorial song. So there’s kind of a full-range in between, so she can kind of express this range of emotions from the one to the other. But you can hear how much harsher this one is than the other one. That’s the much more aggressive song of the female red-winged blackbird.

Now it’s really interesting that male and female red-winged blackbirds have different songs, and that they each have two different kinds of songs, but that’s not even the coolest thing about red-winged blackbirds. The coolest thing about red-winged blackbirds is the other sounds that they give, which we’re going to call the alert calls. Which they give when, they’re mostly by males, when they’re sitting up in the marsh looking around. And they call almost constantly all day.

[Images: Red-winged blackbird male and spectrograms of alert calls; Audio: Red-winged blackbird male alert calls]

Now as you can see these alert calls can take a lot of different forms, right, there’s a lot of different kinds of alert calls that red-winged blackbirds can give. Any individual male at any given time is only going to do one thing over and over again for a while, right. But individual males know between 12 and 20 different alert calls. And most of them are going to have something like every one of the ones pictured up there.

So this starts to look, if we have a large vocabulary of different sounds, and all of those sounds. I forgot to mention this piece, are shared by all the other blackbirds in a given marsh. Alright so if let’s say those ten sounds are the ten sounds of this marsh, every male red-winged blackbird in this marsh is going to know those same ten sounds. Now if you go fifty miles away there might be a slightly different collection of sounds in that marsh. But in any given marsh the males tend to agree on on the language.

So the researchers were very interested in this, because this starts to look like a language, right. Or at least the potential for a language. Because we have different kinds of sounds. Why does, why do red-winged blackbirds need different kinds of sounds? When they’re giving the alarm, when they’re on the lookout for predators. Is it that every different one of those calls is a different level of alarm? Is it that every different one of those calls is a different kind of predator? Or a predator from a different direction? Or something like that.

So they wanted to find out what was going on with this.

[Images: Several red-winged blackbird males and spectrograms of alert calls]

And so, there’s all the other male red-winged blackbirds. They all know the same sounds. They decided to go into the marsh, and they brought with them a stuffed Cooper’s hawk, and they put him under a bed sheet. And they put him on a stick. So they could go out in the marsh and they could stick that stuffed Cooper’s hawk in front of a male red-winged blackbird, but have the bed sheet over the hawk, tied to a string, and then they could retreat, and wait for the male to calm down. Start giving his alert calls again.

And then they would pull the string, and whip that bed sheet off. And from the perspective of the male red-winged blackbird it would be like a Cooper’s hawk suddenly appeared right in front of him. And normally the males are sitting up there in the marsh and they’re all giving the same call, they’re, they pick one of those, like say the chuck call. And male A would be giving chuck chuck chuck, and all the other males in the marsh were saying chuck chuck and they’re all chucking at each other.

[Images: Several red-winged blackbird males, spectrograms of alert calls, and a Cooper’s hawk in flight]

And then they whipped that, that sound off, sorry whipped the bed sheet off the Cooper’s hawk. Let’s see, I don’t think we’re getting the right sounds here. Hmm okay. Let’s try this.

[Images: Several red-winged blackbird males; Audio: Male red-winged blackbird alert call]

If this is the sound they’re all giving, and then suddenly they whip the bed sheet off, the Cooper’s hawk appears, and the call type changes.

[Images: Several red-winged blackbird males and a Cooper’s hawk in flight; Audio: A different male red-winged blackbird alert call]

The male right in front of the hawk changes to this sear call, and as soon as he changes all the other males hear him change, and they switch, too. Starts to sound like maybe that means Cooper’s hawk, or something, or maybe hawk, or or some kind of danger, right.

[Images: Several red-winged blackbird males; Audio: Male red-winged blackbird alert call]

So they did it again. Before the hawk shows up males giving this call, all the males in the marsh are giving this call.

[Images: Several red-winged blackbird males and a Cooper’s hawk in flight; Audio: A different male red-winged blackbird alert call]

And then the hawk appears, and they switch to that one. They try it again, all the males are giving this call before the hawk shows up, and then the hawk shows up and they switch it to that one. And what they started to figure out after they did this a whole bunch is that it doesn’t matter which call they switch to, what matters is that they switch calls. It is the switch in the call that carries the message.

[Slide text: The switch in calls carries the message; Images: Several red-winged blackbird males and spectrograms of alert calls]

All of the actual individual sounds in the system are meaningless. It doesn’t matter which one is the chuck and which one is the seer and which one is the tink. All that matters is that they all give the same call when they’re calm, they match each other’s calls habitually. And they can give the same call when they’re calm. And then when one of them sees danger, anywhere in the marsh, they will send out that danger signal by switching to a different call, and the other males will register that they have received that signal and propagate that signal farther by switching calls with it.

If you’ve ever been really close to a red-winged blackbird nest and gotten a male really upset, you might have noticed that he’s constantly switching calls, no two ever the same in a row, because he’s very agitated, so he’s constantly giving off this danger signal. So how often they switch calls actually is their level of agitation. And this system works because they nest in such close proximity that they’re all in danger together, right. If a hawk is threatening one he’s probably threatening all of them because they’re all right close.

So they need communal vigilance, and because they learn calls from each other they end up with a local dialect. So they all agree on which calls they’re gonna use. It doesn’t really matter which ones they are, as long as they all have the same ones.

When I found out about this it blew my mind because it, it’s indicative of an entirely different relationship between sound and meaning than we are used to as humans. We are used to language in which one sound carries a particular meaning. And yes we have grammar, you know the arrangement of sounds in time, that also carries some meaning. But here we have a system where the individual sounds have no meaning, and the grammar carries all the meaning. The pattern of those sounds in time is is the only message.

This is one of the things that I learned that I tried to encapsulate in my book for everybody else. It’s not everything, but as I said earlier one of the reasons we can talk about this with red-winged blackbirds is because red-winged blackbirds have been extremely well studied in terms of their sounds. And most birds have not been.

That’s actually one of the really cool things about bird sounds, one of the reasons I got into bird sounds, is because with bird sounds we are so much closer to the frontier of bird knowledge than we are with when we just look at them. It is so much easier to go out in your backyard and record a sound that’s never been recorded before than it is to go out in your backyard and take a photograph that’s never been photographed before, of a bird, right.

And when you take sounds and and do recordings you can actually learn new things, that nobody has ever known before, about bird sounds. And you can do this in your backyard. We know a lot about red-winged blackbirds, we still don’t know everything. We still don’t know exactly what that flight song of the male means. We have a guess, but we don’t know for sure.

And there are some really common birds that we do not understand. American robin comes to mind. They have these caroling phrases, and then they have these high-pitched hisselly phrases. We have no idea why they have two different kinds of phrases. We have no idea what that means. Sometimes they’ll do just one, sometimes they’ll do just the other. The other one, the hisselly phrases seem to be used in courtship, but they’re also used by males when there’s no females around. Why? We don’t know. But we could find out if enough people got interested and got out and started recording their robins, and recording their behavior, and uploading their their sounds, and uploading their observations.

So there’s a lot to be learned, and we could, we could learn it right here in this room. That’s what I really love about bird sounds more than anything else.

[Slide text: petersonbirdsounds.com; Images: Cover of the Peterson Field Guide to Bird Sounds of Eastern North America, and male common yellowthroat singing]

So this is the book, that’s the website.

[Slide text: Thank you!

Petersonbirdsounds.com; earbirding.com; audio recordings: Nathan Pieplow, Andrew Spencer, Macaulay Library; photographs: Andrea Westmoreland, Steve Jurvetson, Manjith Kainickara, tsaiproject, USFWS, Matt Tillett, Cephus; Photo: Male common yellowthroat singing]

We can talk more about bird sounds, I’m happy to answer questions, all the questions that you might have. If you’ve got the book, I guess the book is for sale here in the in the shop, but not right now, I don’t think. Or I don’t know, are they’re selling it, are they selling it right after? So I’ll be happy to sign books or whatever, I’m not sure exactly what the schedule is but we can figure something out.

But for now I’d like to open it up for questions, in case anybody has anything. I’d be happy to.

[Applause]

Yeah. Question. This one? Like this sound and that’s sound? Ah, oh that up there? Ah, good question. Okay so the question is on this, we have a spectrogram of a bird sound here, and he’s noticed that here we have a kind of a copy of the original sound above it. There’s actually a second copy, so there’s actually three versions there. And here there’s a sound, and then there’s a copy of the original sound above it. And it, his question is what’s going on with that?

So that’s called a harmonic, and we’re looking at the fundamental frequency down below, and we’re looking at the first harmonic up above. If you have studied acoustics or if you have studied music in any kind of depth, or the acoustics of musical instruments, you understand that a lot of times we have a sound which is a vibration at a particular frequency, and we can also have simultaneously produced by the same vibrating body that made that one sound, will often have other sounds at frequencies that are integer multiples of the first one.

And this is just a consequence of the way that things vibrate in the real world. Certain certain types of vibrations, certain types of things, you get them vibrating and making sound, and they will produce not just one frequency but multiples frequencies of integer multiples of the original one.

And when that happens, what you get is you get copies of the sound on the spectrogram stacked on top of one another. Typically progressively fainter as they go upward, because they’re progressively softer, right, they have less amplitude. Now that’s a simplified answer and it gets more complicated, there’s a lot of things that can happen when we stack whistles on top of each other and they start to sound different.

I get into that in the introduction to my book in terms of how to read different sound qualities, and how to understand those, what we call partials, which are those stacked sounds on top of one another. But for the most part here we don’t have to worry about them too much, they’re just interesting peppy phenomena here in the red winged blackbird. Good question. Other questions?

Yeah. So how does, in in a mated pair of red-winged blackbirds how does the female recognize the male as her mate as opposed to some other mate? So the the the answer most likely is that she recognizes his voice, the same way that we recognize each other’s voice. And so they, there there are certain differences, minute differences in every individual’s songs, that there’s been a lot of evidence in a lot of species that individual birds can recognize each other by voice. In most species, most of the time. Even though they may sound identical to the human ear, even though they may look almost identical in a spectrogram, there are little things that they’re cueing in on that say that one is mine.

And we’ve all heard that you know for example the the penguins in Antarctica, they’re in a big huge colony of a hundred thousand birds, and they can you know find their own chick by ear just by recognizing its call, even if the chick is separated you know and wandering around. Same thing happens in tern colonies, it happens in a lot of birds. Now in addition, individual male red-winged blackbirds actually have different song types, and so there’s there’s actually some larger differences that we could hear even with our own ears that that the females are also cueing in on. But that’s probably the best answer to your question. Good question.

Yeah? Has anyone dissected the spectrograms to show the individual differences that the birds are cueing in on? In some species, yes. As I as I said before this is something that takes a lot of work to to work out, and so it has not been done with all species. In fact it has not been done with the majority of bird species, but in a lot of bird species there is evidence that individuals can be recognized by their sounds.

And we have both behavioral evidence, where we see the individuals responding to their own mates in ways that they’re not responding to others, or responding to tapes of their own mate in ways that they’re not responding the tapes of other birds, and we also have the spectrographic evidence. And that’s usually done, because the differences are so small, that, it’s usually done with statistical analysis.

But yeah there’s been a bunch of studies with statistical analysis that show that statistically speaking you know the the the artificial intelligence can tell this, the the individuals apart too, and so can the individual birds. So but it’s hard for the human ear.

Yes? Do the birds communicate differently with with their fledglings then with then with each other? Like the, yes, yes. So again it depends on the species, but frequently birds will have calls that they give only to the fledglings, and fledglings will have calls that they give only at that age to the adults.

We were in, when we were in Russia last summer, we learned that the great gray owls there. We found a family group of great gray owls, and we learned the warning call of the adults. The adults had this, they would bark at the juveniles, and then the juveniles would bark back to beg for food. But when we started getting too active, and we started getting too close, the adults would switch over to this brrr brrr brrr brrr sound, this kind of low series of growls, and the chicks would shut up at that point.

Because that’s the warning call saying there’s danger here don’t be begging for food right now because we need you not to reveal your location. And then they would bark to the chicks when it was okay to start revealing their location and begging for food again. So that’s a great example from real life that we were just able to observe. But there’s a lot of similar examples from other bird species as well. Good.

Question?

[Man] In microwave electronics when the harmonics are generated, it’s the device that is causing it, but it doesn’t vary. Now maybe there individuals can be differentiated from one another in the bird situation because that’s not a fixed, hard thing, they can shift frequencies a little bit, and that might give them away as to who they are.

[Nathan] Yeah, so the the in microwave frequencies the harmonics above the fundamental frequency are precise, given the given the device right that’s producing them. And in birds the device that’s producing the sounds is a soft tissue, and so it changes shape and it changes tension based on the position of the muscles. And then as that sound comes up through the throat some of those frequencies are filtered out by the throat and the bird can control that to a certain extent. And so that’s how we end up with different sounds. The birds make different sounds on purpose, they also make different sounds by accident.

And that we can tell the difference between them, or statistical analysis can sometimes tell the difference between them. Yeah, exactly. Yes? Do birds make sounds that humans can’t hear? Well, they certainly make sounds that I can’t hear, but then again I have lost a lot of my high-pitched hearing, so there’s a lot of things that that birds say that I can’t hear and that other people can hear.

In general, the conventional wisdom is that the hearing range of birds and the hearing range of humans is pretty similar. We both go up to maybe about 20 kilohertz and in fact in the book I don’t need to actually have hardly any spectrograms that go above 10 kilohertz because almost all bird sounds are below 10 kilohertz, maybe 15, 16, but very rarely do they go above that. So typically birds are creating sounds that we can hear, or that those of us with good ears can hear.

Now there are higher harmonics and there’s been a little bit of work done on is there anything going on up there that’s actually, the birds are paying attention to? So far the evidence seems to be no, that’s not happening.

Cassowaries in New Guinea and Australia, these really big ostrich-like birds, they have a sub-subsonic communication system, where they make really low frequency sounds that are almost too low for people to hear. But you can, if you’re near one so they tell me, I’ve never been there, but if you’re near one you can apparently feel it in your chest when they make these these low sounds. And then low pitch sounds like that are really really good for carrying long distances through dense forests. So that’s how they are able to communicate. That’s a sound that humans might have trouble hearing but we can kind of sense it. Exactly like what elephants do, yeah.

You can. Can you, the question was can you hear the echolocating clicks of oilbirds, and the answer is absolutely yes. And in my one of my other talks that I give I actually start off with a recording that I made in Venezuela when I was inside the mouth of the cave and all the oilbirds were coming back in at 4:30 in the morning for the night. And it sounds like a flock of typewriters because all of them are making these loud clicks, right, and it ends up being this cacophony of sound.

Because the oilbird echolocation clicks are so low-pitched that we can hear them no problem, that means that they’re not as good for echolocation purposes. That means that their picture of the cave is much less well-defined, much lower resolution than what bats can do. But then again oilbirds don’t need quite as much detail because they’re not catching insects on the wing, they’re they’re going after hanging fruit on the wing. And so they they don’t need nearly the resolution that a bat needs for that.

It’s the other way around. So the question is, uh when you hear great horned owls hooting, and one is higher pitch than the other in a pair, is that a sex difference? The answer is yes, and the answer is that the males are lower pitched, but the females are larger physically. So you would expect that the female would have the lower pitched voice because larger birds typically have lower pitched voices, larger musical instruments have lower pitched sounds. But for some reason even though the female is physically larger in all owls it’s consistent, female’s always the larger bird, male always has the lower pitched voice in owls. Which is weird, but yes, you you definitely can sex them by pitch if you’re, if you if you’re listening carefully.

Question back there. Am I aware of studies about how birds hear? Yes, there have been audiology studies on birds, and they’ve taken various forms. Some of them are behavioral, where we play different sounds to birds and see what they react to. And some of them are actually neurological, where they’re getting in there and seeing kind of what fires the auditory nerve, and that’s how we know pretty well that at least in the species that have been studied, their range of hearing pitches is pretty much the same as ours. Good question.

Yeah? Yeah, the question is how, have there been studies on red-winged blackbirds that are banded so that we know kind of whether they’re whether they’re choosing their marsh, I guess, according to their dialect. There have definitely been a lot of studies on banded red-winged blackbirds, so we know a lot about individual interactions, and pair choice, and interactions between pairs and things like this.

There have been a lot of interesting studies done where they take, they capture one of the males for example, and then replace him with a speaker of his own song. And he, that speaker will hold the territory for the male because all the other males will hear that one, and they recognize him, they know like, that’s Joe. Oh Joe’s over there again this morning, so we’re not gonna take over his territory, because we already have established things with Joe, you know. So as long as they, but but if they, but if a stranger moves in, right. If they put different things, then then they’ll come and try to approach and check the bird out and try to see if they can get a little bit more territory off that new newcomer.

In terms of whether they choose marshes according to the sounds, I don’t know the answer to that. I don’t know if that’s been studied as much, because mostly it’s studying the birds that are already on territory in one particular marsh. It’s harder to do things like dispersal and learning of sounds.

But the best guess would be that the birds learn these sounds when they land on their first spring territory in the marsh, and then they use them for the rest of their lives. That’s the way it works with most birds as far as we know. Now red-winged blackbirds are not always nesting in the same exact spot every year. And some of the males will go off and nest in a weird little ditch where there’s two rows of cattails, and no other red-winged blackbirds around, so I don’t know. I don’t think there’s a been any work done on those kind of more marginal birds. Most of the work’s been done in large colonies.

So lots to answer still, lots of questions out there that we still don’t have answers to. I’ve been standing in there looking that way so I want to make sure I’m not missing any questions from the front rows.

Songs and calls, what is the difference? So that’s a that’s a devilish question. The classic definition of song and call is one that was generated by, was the guy’s name Thorpe, I think it was, back in the ‘60s.

And he said that basically songs are, and he generated a list of criteria. Songs are generally complex, they’re typically learned, they’re typically given by males repeatedly in the breeding season to attract a mate and/or to defend a territory. And calls are, tend to, tend to be simpler, they tend to be innate, they tend to form, to serve a range of other functions besides mating functions. So begging for food, warning of danger, contact between flock members. They tend to be given by birds of all sexes and all ages.

Those were her written, his original criteria to distinguish a song from a call. Now when you start actually studying bird sounds you pretty quickly realize that there are very few sounds that actually fulfill every criterion for being a song, and they’re very few that fulfill every criterion for being a call. There are an awful lot that are mixed up, you know. They might be complex and repeated, but they might be innate, right. Like the songs of flycatchers, or they might be, you know, given by birds in contact, but they might be learned, like the flight calls of crossbills.

So we use song and call because they’re kind of convenient shorthand, but they’re questionable in terms of science.

Yeah? Yeah, okay so two-part question. First question is was about postures, the relationship between the posture of the bird and the sound, right? So there’s actually a huge correlation between posture and sound, and this is a great example here. The male red-winged blackbird gets up, he sings, and you’ve seen what they do when they sing most of the time. They’ve got what, they’ve got this display posture that they do when they sing. So they fluff out their feathers, they become bigger, they slightly spread their wings. And those red feathers on the shoulders come out, and they and they flare those. So they’re, they’re making themselves maximally kind of visually interesting, visually conspicuous, right at the moment when they sing.

You see the same thing in grackles. When a grackle sings, if you watch it it just suddenly inflates, and then it and then it kind of goes back to to being slender again. Lots of birds do this. Gulls, right. When they’re giving their long calls, they have these bowing that they do, and they throw their head back, and then they throw their their head up, and do these different postures. And every different kind of gull sound has a different posture that goes with it, so that the visual displays and the auditory displays are closely linked. Part of the same message, absolutely.

Now you can vary the intensity of the message by varying the intensity of the posture, and so a lot of times if red-winged blackbirds are not particularly aroused, and not particularly excited, they’ll just sing and they won’t really do the whole wing spreading thing, or they’ll do it kind of half-heartedly. You’ll probably see that from them sometimes. But if they’re really in kind of a territorial spat they’ll really do the whole thing.

One of the best things I know about bird sounds, and this is again something I put into my other talk, but I’ll share it with you is to since I’m here. There is a bird that always turns its head to the left when it sings, and never to the right. I saw this in the literature I was like are you kidding me? And I had seen this bird and heard this bird sing a million times, and so I started to going out in the field and trying to capture this on video, and actually watching. And sure enough, it’s another one of these things like the red-winged blackbird where if they’re not if they’re not particularly excited, then they might not turn the heads much at all, but every time they turn their heads it’s to the left during the song and never to the right.

Anybody know which bird this is? It’s actually a relative of the red-winged blackbird. It’s the yellow-headed blackbird. Yellow-headed blackbirds turn their heads to the left, and never to the right ,when they’re singing. Now they have two different kinds of songs, yellow-headed blackbirds do. If you if you’re familiar with yellow-headed blackbirds they have a wonderfully horrible sound that they make, like a cat being strangled. And that’s the one that they they turn their head to the left. It’s like they’re being you know forced to sing this song. And they lift, if they lift a wing they only lift the left wing.

And then they have a slightly more musical song that they give, and when they give that song they don’t turn their head to left, they stay straight ahead and they do both wings. So there’s two different kinds of songs, and there’s two different kinds of displays, one for each song.

What about the beats? This was the second half of your question. Do birds have beats? Do we, do we hear these rhythmic songs with repeated elements, and then we see repeated elements of the of the bird sound. So it’s difficult to say exactly the extent to which birds have rhythm, but yes there are, there are rhythmic types of display, displays, like flapping. Some of them are mechanical, so for example if you actually watch a song sparrow sing, and he gets to the trill at the end of his song, or in the middle of a song, you’ll actually see his tail often kind of flapping with each note of his song. But as far as we know that’s probably mechanical, that’s from the effort required to get each sound out and not, it’s not really a display per se. It’s just an incidental movement.

But there are lots of birds, I can’t think of a good example right off the top of my head, of a bird that does a repeated motion, with a repeated sound.

Yeah manakins, I’m trying to think what manakins do. Manakins can do all sorts of dancing, and swing, flapping and snapping. They do they do a lot of crazy dancing and moonwalking, and all sort of, check out, check out videos of dancing manakins, and see see if maybe some of them have rhythm like you’re like you’re hoping they do.

I was going to say gull calls is kind of, there’s there’s kind of some rhythm there, too.

But, so some of the some of the gulls, like ring-billed gull, right. Well when they’re when they’re doing, again it’s like red-winged blackbirds, they don’t always do the full display postures when they’re giving the long call, but if you watch a ring-billed gull giving its long call, it’ll do the bow at the start, it’ll bring its head back, and then with each of the last hoarse notes that it does, it’ll pump its head up. And so that’s, and that’s that’s definitely more than is required to make the sound, right.

So it’s something about the display that. So there there are some birds that do, and there’s probably better examples, too. I can’t think of anything off the top of my head. But I hope that that helps answer you a question.

[Matt] All right on that note, let’s get Nathan a round of applause.

[Applause]

And as Nathan said, he’ll have, there’s some more books out here, we’ll be out here and he could sign some books for people. We’ll be hanging out for a while, but thanks everyone.

[Nathan] Thank you.

[Matt] Thank you.

[Nathan] You’re welcome. Thanks for the introduction and the opportunity to come here.

End of transcript