Singing songs could be a better (and non-violent) way of ensuring the fidelity your female partner — than aggressively bashing up potential competitors — at least where the notoriously promiscuous Australian red-backed fairy wrens (Malurus melanocephalus) are concerned.
The red-backed fairy wrens are not known for their fidelity, and the male wrens have to figure out how they can ensure — to the extent they can — that they are not raising another wren’s chicks.
Scientists from Cornell University’s Lab of Ornithology thought that aggressive posturing by male fairy wrens would probably help ward off other males effectively. But it turns out that singing duets with the female wrens was more effective.
The scientists tested whether male paternity was linked to aggression or duetting in the fairy-wrens, by simulated territorial intrusions. “Males with quicker and stronger duet responses were cuckolded less often than males with slower and weaker responses. In contrast, physical aggression was not correlated with male paternity,” the scientists report.
Fake fairy wrens and song recordings elicited various levels of aggression, though.
Here’s a link to the research abstract in Biology Letters : and