Canberra, March 5 (IANS): A team of international researchers has found that bird song is almost as common in female birds as in males, overturning theories that it was an exclusively male trait.

The findings, released by the Australian National University (ANU) Wednesday, challenge assumptions about sexual selection in birds, and pose new questions about Darwin's theory of sexual selection and the evolution of elaborate bird song, reports Xinhua.

The research conducted by the University of Maryland, the University of Melbourne, the Australian National University and Leiden University in the Netherlands has been published in the journal Nature Communications.

"Darwin focused on the evolution of song through sexual selection, and assumed bird song was a male trait to attract females," said report joint author Naomi Langmore, from the ANU's Research School of Biology.

"Our findings suggest that bird song may have evolved through a broader process, called social selection, as both sexes competed for food, nest sites, mates and territories."

Darwin had suggested the primary role of female birds was to listen to the songs of the males, and instances of female bird song were traditionally dismissed as rare or the outcome of hormonal aberrations.

But the latest study found female song was present in the ancestors of all songbirds, and today remains in 71 percent of the songbird species surveyed.

In Australia, Langmore said most present songbird species feature bird song from both males and females, including lyrebirds, fairy-wrens, honeyeaters, fantails, whistlers, and magpies.

She said the songs from male and female birds were equally melodic.