AUTHOR BLOG: Recognizing the Importance of Female Birdsong

Karan Odom & Lauryn Benedict

Linked paper: A call to document female bird songs: Applications for diverse fields by K.J. Odom and L. Benedict, The Auk: Ornithological Advances 135:2, April 2018.

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House Wrens are among the familiar birds in which females sing. Photo credit: J. Hudgins/USFWS

Can you name ten North American or European bird species in which females sing? Can you name twenty? Fifty? That may seem like a lot, but in fact it’s only a small percentage of temperate-zone bird species with female song. There are at least 144 North American passerine species with female song, and many more non-passerines with elaborate vocalizations that could be classified as song (defining “song” is a topic we won’t even go into here!). Across all avian species, approximately 64% have female song, but these estimates are rough. The true numbers could be much higher. Why are the estimates so rough? Because documentation and reports of female song are lacking. We highlight this problem in our paper “A call to document female bird songs: Applications for diverse fields.” We ask all of you to help us address the deficit.

We know that the data are out there; we regularly have conversations with ornithologists and citizen scientists who tell us that they have observed singing females in myriad species. Our response: Publish it! Archive it! We’ve chatted with many senior researchers who have years of data including observations and recordings of female song in their study populations, but who haven’t published these data because female song is rare or is not their main research focus. We’ve also heard from students working as field assistants whose cohorts regularly observe singing females, but those observations are seldom documented. On field projects with many technicians, word-of-mouth data can be extensive and highly informative, but staff turnover means that known population traits never get put down on paper (or audio).

Citizen scientists frequently tell us about singing females, and many of them have taken the next step to document their observations through The Female Bird Song Project. Contributors have recorded female song in species as diverse as the Mexican Sheartail (Doricha eliza), Black-goggled Tanager (Trichothraupis melanops), Saffron Finch (Sicalis flaveola), and Cerulean Warbler (Setophaga cerulea), all of which seem to be the first documentation of female song in their species!

Each of these contributions plays a role in understanding the distribution of species with female song – data that researchers can use to address a wide range of biological questions. A complete picture of when and how female birds sing will offer insights into the biological mechanisms, evolution, and applications of avian vocal signals. Neurobiologists can ask how bird brains perceive and produce these variable signals, and whether that differs by sex. Evolutionary ecologists can ask why songs differ among species with different ecology and life-history traits. Conservation biologists can use songs to census and monitor the presence of males and females across populations.

What can you do? Don’t assume that a singing bird is a male. Look, listen, and document without bias. Teach your students to do the same. In 73% of all bird species we lack enough published information to even determine whether females sing. We are confident, however, that in some of those species females do sing because we have talked to colleagues about them. Common knowledge suggests that female song is rare, but our experiences make us question that: if all ornithologists talked to each other about female song the way that they talk to us, then that assumption would change. Your random observations of a female warbler singing can probably be backed up by the observations of many others. Females of temperate-breeding species may not sing as often as males, but when we pool all our knowledge and observations it’s likely that we’ll find more parity than we expect.