In a new study published in May 2021 in the journal Frontiers in Psychology, an interdisciplinary team of researchers made an attempt to describe the specific compositional rules behind the song of the northern mockingbird (Mimus polyglottos), focusing on the way the bird transitions from one syllable type to the next.
The mockingbird uses musical techniques like those of humans. Image credit: MPI for Empirical Aesthetics.
Among songbirds, the mockingbird has an extraordinarily variegated song that is much more complex than most species’ songs.
Mockingbirds have enormous repertoires of song elements which are arranged in a particular way: individual syllables, which can be a single sound or a small group of sounds, are repeated to form short phrases, which, in turn, are strung up into long songs that can go on for minutes.
As indicated by their name, mockingbirds are also famous for their ability to mimic.
They will mimic the sounds of birds and other environmental sounds, as long as these sounds are acoustically similar to the typical acoustic feature range of mockingbird vocalizations.
Studies of model selection show, for instance, they mimic blue jay calls but not raven calls, American robin calls but not American robin songs, tree frogs but not bullfrogs.
“When you listen for a while to a mockingbird, you can hear that the bird isn’t just randomly stringing together the melodies it imitates,” said Dr. Tina Roeske, a neuroscientist at the Max Planck Institute for Empirical Aesthetics.
“Rather, it seems to sequence similar snippets of melody according to consistent rules.”
“In order to examine this hunch scientifically, however, we had to use quantitative analyses to test whether the data actually supported our hypotheses.”
In the study, Dr. Roeske and her colleagues — Elon University field biologist Dr. Dave Gammon and New Jersey Institute of Technology music philosopher Dr. David Rothenberg — analyzed song material from five individual mockingbirds.
“We would like to think that our study shows the value of combining different forms of human knowledge in the investigation of a single problem,” they explained.
“When confronted with a complex mockingbird song, a musician will hear one thing, an ornithologist another, and a signal analyst something else.”
“The most complete human knowledge of any natural phenomenon comes from combining distinct human forms of knowing — no one perspective negates the others. They are strongest when applied together.”
The scientists were able to identify four compositional strategies that the birds use in transitioning from one sound to the next: changing timbre, changing pitch, stretching the transition (lengthening it in time), and squeezing it (shortening it in time).
“The complex melodies they create are music to the ears not only of other birds but of humans as well,” they said.
“So, it should come as no surprise that (human) composers of varied musical styles use similar techniques in their work.”
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Tina C. Roeske et al. Mockingbird Morphing Music: Structured Transitions in a Complex Bird Song. Front. Psychol, published online May 4, 2021; doi: 10.3389/fpsyg.2021.630115
