More and more scientists are turning their attention to female birds, uncovering new behaviors and changing the way we think about evolution (see the recent Living Bird article).
Karan Odom, a Cornell Lab of Ornithology postdoctoral researcher, and her team used assets in the Macaulay Library and discovered that female bird song is present in 64% of songbird species that exist in the world today. Prior to this discovery, most people especially in the Northern Hemisphere, tended to think of bird song as a behavior exclusive to males, because in the Northern Hemisphere many male birds are conspicuous and vociferous. But around the world, in more than 600 songbird species, female birds are known to sing.
Recently researchers in Indiana added a new species to the list of species with female song, the Cerulean Warbler. Garrett MacDonald and colleagues from Ball State University, documented female song in two Cerulean Warblers.
One female sang longer and more complex variations of the typical “zeet” call from her nest during the incubation period often after the male sang. This female only sang when she had eggs in the nest and stopped singing once the eggs hatched.
The other female sang a series of “zeets” only during the nestling stage while foraging near the nest. To hear this song, turn the volume up and look for a series of paired lines in the spectrogram.
MacDonald and colleagues suggest that the female song they documented likely helps females maintain the bond with their mate. But females may sing for other reasons too and MacDonald and Odom urge birders and ornithologists to listen up and try to document female song.
To help researchers learn more about female song, check out the Female Bird Song Project and add your field recordings to your eBird checklist.
MacDonald, G. J., C. D. Delancey, K. Islam. (2019) Novel vocalizations, including song, from 2 female Cerulean Warblers (Setophaga cerulea). The Wilson Journal of Ornithology 131:366-373.
Odom, K. J., M. L. Hall, K. Riebel, K. E. Omland, and N. E. Langmore. (2014). Female song is widespread and ancestral in songbirds. Nature Communications 5:3379.