SCIENCE

These Sparrows Sing to the Beat of Their Own Drum

Java sparrows amp up their tunes with acoustic beak taps synchronized with chirps

May 20, 2015

When Java sparrows make love, they do it to the beat of their own in-house avian techno. As at a rave, the birds’ melodies begin slowly with the tap of a few drums—in this case, click-like sounds created when the sparrows grind their beaks. Gradually the music builds until the song culminates in a frenzied mix of treble—the male’s high-pitched chirps—interspersed with rhythmic clicks. In this way, amorous sparrows perform as both vocalists and percussionists.

While plenty of birds are musically inclined, their tunes are usually limited to songs produced vocally—not with the additional aid of drumbeats. Java sparrows stand out as the exception. Males are known to make bill-click sounds when they woo females as well as when they sing by themselves. Females also click during courtship, seemingly backing up their partner’s sexy song. Neither males nor females have ever been observed making bill-clicks in the absence of vocal singing, leading ornithologists to suspect that—rather than a physiological anomaly—the clicks actively contribute to the music.

Here, you can see the mating rave:

To confirm whether this is the case, two researchers from Hokkaido University in Japan investigated whether the clicks are synchronized with the overall song, and also whether clicking is a learned or innate behavior. They studied 30 domesticated male Java sparrows, some of which were father-son pairs that had been kept together. Seven of the birds had never spent any time with other Java sparrows before, however, and one was raised in the company of Bengalese finches, a species that does not make clicking sounds. The researchers recorded the various songs each bird produced, averaging about 24 songs per individual, and then used song analysis software to identify acoustic structures and individual song notes from bill clicks.

Listen to a few of the research subjects clicking and chirping away here:

As the researchers report in the journal PLOS One, 18 of the sparrows clicked in more than 60 percent of their songs. The clicks, they found, tended to occur more frequently at the beginning of a song—like a drummer kicking off a song with a stream of percussion—and also around certain notes in the melodies. The father-son pairs tended to use similarly patterned clicks in their songs, but the loner birds and the one reared by foster finch parents also produced clicks of their own. This implies that, while the musical structure of the clicks can be passed on to other birds, the clicking behavior itself is not a purely learned behavior, Java sparrows seem to include clicks as a natural part of their music repertoire.

While past studies have shown that some birds dance—bowing or opening their wings to the rhythm of their songs—this is the first study to show that some song birds may also incorporate coordinated, deliberate percussion with their tunes.

Why Java sparrows have evolved to be percussionists as well as vocalists remains unknown. But the researchers wonder if it might have something to do with facilitating a courtship duet between males and females. Further studies will help answer that question, as well as reveal whether other species are also bill-click ravers.