Rainforest birds 'jam' partner's song to prevent cheating

by Rich Bowden - Mar 15 2009, 20:26

Female rainforest birds use their ability to "jam" the songs of their mates in situations where an unattached bird threatens, according to a new study.

Researchers at Oxford University found the female Peruvian warbling-antbird, when threatened by competition from an unpaired rival, will attempt to block out the song, which then sees the rival respond by singing a more complex tune.

"Single females are a threat to paired females because they increase the likelihood that males will cheat on their existing partner, or abandon them in favour of a new one," said Dr. Joseph Tobias of Oxford’s Department of Zoology, who led the work.

"We know that divorce, in particular, is common in antbirds. The presence of single females therefore leads to a kind of acoustic battle in which males and females have rather different priorities," he said in a university news release.

The research, which is reported in the journal Current Biology, followed 17 pairs of antbirds in the Peruvian rainforest and tricked the birds into believing a rival pair had entered their territory in the first experiment and that an unattached female rival was close at hand in the second test.

"Resident pairs faced with a rival pair responded in concert with a simple, precisely coordinated duet," said Dr. Tobias. "However, when they heard a single female, the coordinated duet broke down as paired females attempted to jam – effectively to ‘block out’ – the notes being sung by their own partners. Males then countered this strategy by changing their songs in an attempt to avoid interference, resulting in a more complex acoustic display."

The birds attempt to avoid being "jammed" by changing their tune "[which] helps to explain the recurrent evolution of complex communal signals in many lineages of birds and social primates, and may provide a useful clue to the origins of human music," said the statement.

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