Birdsong: There’s rhythm & news in this research project

Inca Dove. This bird species’ coos (and dozens more) have been converted into musical notation.
Copyright William F. Walker, http://www.birdwalker.com

When Nat Wheelwright listens to birdsong, he hears information—what a bird is communicating to a potential mate, rival, or eavesdropper. Robby Greenlee hears colors, rhythms, and melodies. They may not be birds of a feather, but the two Bowdoin College professors—one an ornithologist and the other a composer and music theorist—are teaming up to transcribe and analyze a variety of birdsongs. In the process they hope to uncover new evolutionary and musical insights.

To launch their project this past summer, they enlisted John Butterworth, a Bowdoin student and jazz saxophonist, to transcribe into musical notations more than 50 dove and pigeon coos from recordings contained in the vast digital collection of the Cornell University Lab of Ornithology. They eventually hope to move on to other bird species, such as Baltimore orioles and brown creepers, but they wanted to start with relatively simple vocalizations. “It’s extremely difficult to transcribe, because birds do such complex things,” Greenlee says.

An American naturalist named F. Schuyler Mathews may have been the first to attempt to put birdsongs into western notations in his 1907 guide, Field Book of Wild Birds and their Music. “He gave up when he got to the bobolink because it got way too complicated,” Wheelwright says. “His biology [in this book] is pretty bad, and he didn’t get the ecology,” Wheelwright says. “I think because it was a failed experiment in terms of being useful scientifically, it gave transcription to western symbols a bad name. I’m not aware of anyone who’s done it since.”

But Wheelwright and Greenlee saw a need for their transcription project after co-teaching a popular course called “Bird Song, Human Song,” which explored similarities in both kinds of music. Students learned everything from the mechanics and endocrinology of sound production to an appreciation for how the mourning dove’s syncopated coos match the refrain from The Beatles’ “She Loves You.”

“In that class we were asking more questions than we could answer,” Greenlee says. “We realized that nobody had explored this from a scholarly or academic perspective,” adds Wheelwright. “I’m not really aware of a collaboration like this between a musician and a biologist.”

Click here for a link to a recording of an Emerald Dove (Chalocophaps indica) from the Macaulay Library at the Cornell Lab of Ornithology.

Below is the Emerald Dove transcription by Greenlee, Wheelwright, and Butterworth:

Musical notation based on Emerald Dove. Greenlee notes: “”Meter is 4/4, and pitches are approximately G-F#-G, or later in the coo, G-G-Ab. Most notable is the use of articulation (a short note, indicated by a dot above the note) to assist in establishing a meter.”
The top figure is an oscillogram and shows amplitude (loudness) of different notes. The one below, aligned in time, is a sound spectrogram or sonogram, showing frequency (pitch), including harmonics and other overtones (which give a sound its distinctive timbre).

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Their initial work on dove vocalizations shows that birds within the same evolutionary branch, or clade, seem to share musical characteristics. For example, says Wheelwright, “the mourning dove [found in the United States] seems to sing in simple time, where the beat is divided into a multiple of two, whereas some of the Old World doves [which belong to a different clade] sing more in compound time, where the beat is divided into three.

“Birds that are closely related tend to sing the same way, which is different from other characteristics like color, which tends to be something very much related to your environment,” Wheelwright says.

Greenlee is more interested in the music itself—“the kinds of rhythms, colors, and melodies” the birds use. “I was just amazed that every dove we encountered created a rhythmic world that is similar to the rhythmic world most humans use when they make music,” he says. “It’s metrical. There is a regularly occurring period of time that we call a beat, and in addition to that, some beats are more important than others. Some have a strong assertive accent and some are weak.”

Working with Wheelwright has challenged Greenlee to scientifically quantify the musical patterns he hears in bird music. “I realized there is so much I have to take into account when figuring out how long each of these pulses should be, figuring out which was strong and which was weak, and how a pattern occurs [so that] this is something that somebody else could replicate and get the same results.” That close attention to detail, for example, helped Greenlee to see that the Mourning Collared Dove is more precise in creating meter (only 2/100 of a second off) than humans are.

That sense of discovery is mutual. “I had to smile at the syncopation” of some doves, Wheelwright says. “It just sounds like rock music. They create an expectation of a beat and leave you hanging … or they accelerate it. My intuition tells me the reason they do it is precisely the same as in human music,” he says. “It’s the little surprise it carries to the intended audience.” For birds, it might be just the right technique to catch a mate’s attention.

“I’m always listening for the information content of a song,” Wheelwright says. Among other things, he wonders if “floater males” use it to gather information about the age, motivation, and genetic characteristics of other males: “Are they the product of inbreeding, and are they not as genetically diverse as some individuals and might that make them a weaker competitor? I think all of that is potentially reflected in the sounds birds make,” he says. “There is information in birdsong.”

And beautiful music, too. Once they finish analyzing the dove coos, Greenlee hopes to turn their attention to the thrush family. He says, “The Hermit Thrush will sing harmonies as complex as jazz chords.”

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