There’s a new paper in Science, brought to my attention by Ritchie S. King in the New York Times, that describes an amazing behavior in plain-tailed wrens (Pheugopedius euophrys). The species is neotropical: found in tropical forests in the mountains of Peru, Ecuador, and Colombia. Here’s a photo from Wikipedia:
What’s amazing about this species is that the duet sounds like a single song, but actually consists of males and females alternating “syllables” at a rate of up to six per second. When the female’s song has a tiny gap, the male fills in. You can hear all this in the video below, and I’ll embed some songs from the paper. The function of these songs is unknown, but they are probably involved in joint defense of territories.
The researchers, Eric Fortune et al., spent several months in the bamboo forests of Ecuador, recording wild and captive birds. They also did playback experiments using “artificial song”. The main results are described very well in this three-minute Science video below, presented by Fortune. You’ll hear the duets as well as the single songs of one sex, showing the gaps that are filled in by the partner.
The authors found that the partners don’t just sing a stereotyped song, but adjust their songs to fill in whatever gaps are provided by the partner. In other words, they’re sensitive to audio feedback from their mate, and, as the authors note, “are not relying on fixed-action patterns in the brain to generate duet song.” As Fortune notes above, the female seems to play the “lead” in these songs, much like a partner who leads during a waltz.
Now I’m not sure if you can see this for free, but I’ll put the links to two movies of caged, duetting wrens. Below each movie is a sonogram that shows which partner is contributing which syllable.
Movie 1. “Top bird is the male wren, bottom the female. At the bottom is an oscillogram with the male and female parts marked in blue and magenta, respectively. The female initiated the duet, and the male moves its beak in its first interval but did not produce a syllable (1.11 to 1.36 seconds in the movie).”
Movie 2. “This movie shows duetting in a captive pair of plain-tailed wrens. The bird visible at the start of the movie is the male, and the female becomes visible in the upper right hand corner. At the bottom is an oscillogram with the male and female parts marked in blue and magenta, respectively. Singing-related movements can be seen in both birds, but is particularly evident in the tail of the female at the end of the duet.”
And some audio recordings from the paper, showing both duets and single-sex songs:
- Audio S1 Audio recording of the plain-tailed wren duet song shown in Figure 1A.
- Audio S2 Audio recording of the solitary female plain-tailed wren song shown in Figure 1A.
- Audio S3 Audio recording of the plain-tailed wren duet song shown in Figure 1B.
- Audio S4 Audio recording of a solitary male plain-tailed wren song shown in Figure 1B.
- Audio S5 Audio recording of a plain-tailed wren duet song in which the male skips a motif, as shown in Figure 1C.
Fortune, E. S., C. Rodríguez, D. Li, G. F. Ball, and M. J. Coleman. 2011. Neural mechanisms for the coordination of duet singing in wrens. Science 334:666-670.