Birds Cut Rivals Off in Mating Songs

For male nightingales, the key to scoring with the ladies is to cut their opponents off.

Male songbirds often compete for mates through singing contests.  The dominant ones usually start singing before an opponent finishes his song, signaling aggression that female birds sometimes find attractive.

[AUDIO: Hear the Birds Overlapping]

In a study of nightingales, scientists were interested to learn why 49 percent of the males didn't have a mate during breeding season.

"One possibility is that they select their future mate on the basis of the performance during a vocal interaction, because nightingales interact for hours during the night," said Hansjoerg Kunc, a researcher with University of Zurich, Switzerland.

A cappella test

Kunc and his colleagues played recordings of nightingale songs near the territories of males that were successful in finding a mate. And did the same thing with males that had no partners.

They then counted the number of songs that each group interrupted or overlapped.

"Females pair with males that overlap more songs during a vocal interaction with a rival," Kunc told LiveScience in an email interview.

Female nightingales see song overlapping in a potential mate as a sign of aggression, an indication of other beneficial qualities. These males might be in better health and thus able to defend a territory better than males in poor condition, Kunc explained. And because aggressive males are more likely to have a mate, they also have a higher rate of reproductive success.

Other species

The nightingale is one species where song overlapping might play an important role, but black-capped chickadees, great tits, little blue penguins, and domestic canaries might also use this mechanism, Kunc said. "Furthermore, this phenomenon does not only occur in birds," but also in crickets, frogs and toads.

There is no clear evidence that this type of dominance rules when it comes to finding a mate in other species such as primates, the scientists say.

This study was detailed in a recent issue of the journal Animal Behavior.