Listen to the mockingbird. This bird makes a lot of noise. He copies all sorts of other bird songs, repeating, repeating, over and over, sometimes for hours. People must have thought this behavior was vaguely insulting to other birds, else we wouldn’t have named this one the mockingbird.
But now, listen more closely. You’ll hear that this virtuoso bird isn’t just copying other species’ tunes. He’s sampling them like a DJ and transposing, bending, tweaking them into his own quite deliberate form. We can always tell it’s a mockingbird, not because of his copying, but because of his unique and specific way of composing music out of the material he hears in the world around him.
It turned out that no humans had specifically articulated what these birds were doing, so my colleagues and I decided to delve deep into the mockingbird’s process, using the analytical tools of three different disciplines at once: biology, music and neuroscience. Our paper, published in early May in Frontiers in Psychology, argues that the mockingbird, one of the American birds with the most complex of songs, uses musical techniques familiar to composers from many kinds of human music.
Our thesis is that mockingbirds use four compositional strategies to create their melodious song: timbre change, pitch change, stretch and squeeze. This allows the birds to transition from one sound to the next in ways that tickle the ears of both songbirds and people. We called this overall activity morphing, a phrase more familiar in imagery but that works for audio just the same.
I’m a philosopher and musician, a person who does not usually work on scientific papers. But I have written about scientific method many times, in popular books like Why Birds Sing, Bug Music and Survival of the Beautiful. All of these works put science in the context of culture, and most deal with the music of the animal world in one way or another.
Long fascinated with the compositional methods of the mockingbird, I finally decided to dig deep into his sense of form and structure. For that I needed the help of the greatest expert on listening to these birds, Dave Gammon, professor of biology at Elon University, who has studied the large population of mockers on his campus for many years now. He knows about 20 individual singing males by name, and can identify by ear most of the species each one imitates and which sounds are not imitations at all. …“When you listen to a mockingbird,” he says, “they repeat an individual phrase three or four times, and then they're doing something new, and then doing something new again.”
“And after you've listened to them for just a minute,” Dave adds, “you've heard 20 to 25 different song phrases and they're still pulling out new ones. If you listened to them for 10 minutes, you might be hard pressed to recognize anything that was repeated. The diversity is huge, and it's so loud, so conspicuous. I always felt they were composing with these diverse sounds, and that the organization of their song phrases might be perceived by humans.”
Dave also insisted that we compare these songs to human music. As someone who’s studied a lot of ethnomusicology, I was a bit afraid to do that. Immediately opens a can of worms! Which human music? But I was impressed by his examples: Beethoven’s Fifth symphony for pitch change; the Tuvan throat-singing ensemble Huun-Huur-Tu for timbre change; and Idina Menzel from Disney's Frozen II for stretch. All we needed is an example for squeeze, so I immediately thought we needed something from hip-hop, and I was sure Kendrick Lamar’s album Damn would have something. It really had everything, and the last piece on the album, “Duckworth,” sounded more mockingbirdesque than anything we found. It didn’t win the Pulitzer Prize in composition for nothing.
Okay, we had all these cool examples; look, mockingbirds play with sounds just like humans do. We call what humans do music, so why can’t the birds be making music?
“It’s all fine to propose the bird is doing something,” says lead author Tina Roeske of the Max Planck Institute for Empirical Aesthetics in Frankfurt. “But for science, we must analyze the data to show that our assertions fit the data.” She designed the algorithms that tested the paper’s hypotheses. The statistics support our hypotheses, and that is what it takes for something to become science." She explains her methods: “I'm the kind of scientist who just loves the really not so sexy stuff. I really just sit in front of the computer and listen to stuff and try to recognize structure.”
She continues: “I mean, I love when I can show that a pattern that I perceive and perhaps find beautiful is truly there; it's like finding a proof that this is real. It's not a random thing. It's really there; start thinking about why is it that we also have this strong, subjective response to the mockingbird’s song. And that's really interesting. And I don't think the analysis takes away from the beauty of the song itself.”
In my books, I have long argued that for humans to best understand any phenomenon, we have to combine all the different forms of knowledge at our disposal. Poetry says one thing about mockingbirds, as in Walt Whitman’s “Out of the Cradle Endlessly Rocking.” Music says another: “Listen to the Mockingbird.” Ornithology says: here are all the species the mockingbird copies. Neuroscience says: look at these numbers that prove our intuitions about pitch, timbre, stretch and squeeze are correct.
Each form of human knowledge has different criteria for truth. None reduces to the others or cancels each other out. But all can be impressed by beauty in a bird’s song, albeit in different ways. Charles Darwin knew this full well, observing in The Descent of Man that birds have a natural aesthetic sense. “That’s why they evolved such beautiful songs,” I told a reporter at Elon University. “It takes the full range of human forms of knowledge to figure out what they are up to. Not one of us could have done this research alone."
The paper, and all its data, are free to view in the open-access journal Frontiers in Psychology. And this video version demonstrates how this bird makes such special music out of the songs of so many other birds in his habitat. If we take its music more seriously, our own sense of music expands to care just a little more about the world of nature that surrounds us and made us possible in the first place.