Like a jealous woman intercepting her flirtatious husband's overtures to another woman, a female bird of one species jams her male partner's love messages to keep the signals from reaching another female, a new study suggests.
Female antbirds will sing over the songs of their male partners when an unattached female is nearby. The tactic apparently drowns out the male songs, according to a new report published online in the journal Current Biology. Males respond by changing their tune.
In other bird species, males are known to cut rival males off in song. Urban birds have been shown to change their tune completely to combat city noise. But the new findings offer the first evidence that such "signal jamming" and "jamming avoidance" occur between mates, according to the researchers.
"In human terms, signal jamming is most commonly associated with attempts to scramble information in radio, radar or cell phone signals," said Joseph Tobias of the University of Oxford. "The females in our study try to do a similar thing with the songs of their partner, but the overall situation is more analogous to a wife continually interrupting her husband to stop him from flirting with a single woman."
Tobias and his colleagues found that pairs of antbirds sing coordinated duets when responding to rival pairs. But under other circumstances, cooperation breaks down, leading to more complex songs and the apparent attempts at jamming.
Tobias said the jamming is presumably intended to make the males less attractive or to make it clear that they are "taken." He added that the results in antbirds may have broad implications for understanding how communal signals have developed over evolutionary time in many animals, and perhaps even in humans.
"Most evidence points to vocalizations in early humans having a function in both mate attraction and resource defense, so it seems plausible that 'signal jamming' and especially 'jamming avoidance' played a role in our evolutionary history," he said. "If so, our results may help to explain the first steps towards complex, coordinated group signals in humans, which themselves are the likely forerunners to modern music."
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