Science Literature

The songs of female birds have attracted very little research interest, with males made the focus of attention because of their plumage and their songs. "Males do the singing and females do the listening" is the preconception of most academic studies. The new research tested the hypothesis that female singing is ancestral and that absence (rather than presence) is the derived trait. The authors write: "To summarize (. . .), we demonstrated that song in females could be an ancestral condition, from which sexual selection may drive females of some species to give up singing." This appears to be an interesting example of evolutionary thinking inhibiting thought processes. "Garamszegi blames Charles Darwin for the oversight. 'He emphasised the importance of male sexual display, and this is what everyone has been looking at.'" Female bird song appears to be yet another case of the ancestral condition being anything but simple.

The evolution of song in female birds in Europe
Laszlo Zsolt Garamszegi, Denitza Zaprianova Pavlova, Marcel Eens, and Anders Pape Moller
Behavioral Ecology, 2007, 18: 86-96; doi:10.1093/beheco/arl047

Abstract: Bird song is usually regarded as an attribute of males. However, in some species, females may also produce songs even with comparable complexity to that of males. It has been suggested that female song may evolve due to similar selection pressures acting on males, but no study has yet investigated the evolution of female vocalization in a phylogenetic context, a gap that we intended to fill with this study. Based on standard descriptions in The Birds of Western Palearctic, we classified 233 European passerine species with respect to whether females are known to produce songs or not. We were more likely to find information on female song for species whose song is more studied than for less intensively studied species. When we traced information on female song on a phylogeny, we found that at least in 2 avian families, female song appeared to be the ancestral state, but such an ancestral state may be expected to be even deeper in the phylogenetic tree with increasing information on female song. In fact, we cannot exclude the possibility that the ancestor of European passerines had females capable of singing. In a preliminary comparative study based on the available data, we found some evidence that female song may have evolved under the influence of sexual selection as carotenoid-based dichromatism was positively related to female song among species. Our findings imply that due to publication bias, the evolutionary importance of female song is generally underestimated.

See also:
Are female songbirds evolution's unsung heroines?
New Scientist, 3 February 2007, page 17.

MALES do the singing and females do the listening. This has been the established, even cherished view of courtship in birds, but now some ornithologists are changing tune.
[snip]Females that sing have been overlooked, the team say, because either their songs are quiet, they are mistaken for males from their similar plumage or they live in less well-studied areas such as the tropics (. . .). Garamszegi blames Charles Darwin for the oversight. "He emphasised the importance of male sexual display, and this is what everyone has been looking at."
[snip]