Female birds sing songs as sweetly

Long-held theories that bird song is an exclusively male trait are being challenged with the finding that bird song is almost as common in female birds as in males.

The research, conducted by an international team including researchers from the University of Melbourne and the Australian National University, found that female song was present in the ancestors of all songbirds and today remains in 71% of the songbird species surveyed.

The findings challenge and raise new questions about Darwin’s theory of sexual selection and the evolution of elaborate bird song.

“Darwin focused on the evolution of song through sexual selection and assumed birdsong was a male trait to attract females,” said Dr Naomi Langmore, from the Australian National University’s Research School of Biology, one of the researchers involved in the study.

“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.

In Australia, Dr Langmore said most extant songbird species feature bird song from both males and females, including lyrebirds, fairy-wrens, honeyeaters, fantails, whistlers and magpies - and the songs from male and female birds were equally melodic.

Female bird song was less common in a recently evolved group of songbirds that is more prevalent in Europe and North America, which may explain why the old assumptions lasted for so long.

The work has been published in the journal Nature Communications.