2020 BSJ Blog Fall 2020

The Return of Birdsong

By Rebecca Park

When was the last time you heard birdsong over the cacophony of honking cars, screeching tires, and roaring engines? Chances are, probably not recently—and even if you did, it would be like hearing the thin cry of a lost child in the midst of a bustling crowd—nearly imperceptible.

Unlike lost children, male birds in particular compose intricate symphonies to attract mates and defend territory. However, to make themselves heard over anthropogenic clamor, city birds have no choice but to increase the frequency of their songs which causes a decrease in frequency bandwidth and, consequently, vocal quality.

This appears to be the case for the white-crowned sparrow. If they are to produce the more complicated components of their songs, such as whistles and trills, the avians must sing with excellent vocal quality in the form of fast and precise vocal tract movements. A recent study conducted this year by Dr. Elizabeth Derryberry, a behavioral ecologist specializing in ornithology at the University of Tennessee, examined the effects of San Francisco’s citywide shutdown on the quality of white-crowned sparrow calls. Her investigation sought to identify any behavioral changes linked to the sudden decline in noise levels in the area of study.

Over several months, Dr. Derryberry and her research team recorded the calls of the white-crowned sparrow in the now-quiet Bay Area streets. After comparing these recordings with previously collected data of the birds prior to the pandemic, they discovered that the species now produced higher quality songs: while the past recordings showed that the birds sang at louder volumes in an effort to be heard, because the decline in ambient noise enabled the birds’ calls to transmit across a larger area, they did not need to strain their calls as much to be heard.

The team’s findings highlight the resilience of birds: the remarkable speed at which birds have improved the quality of their songs serves as a testament to their ability to recover from the harmful effects of noise pollution. Following this discovery, future researchers could further investigate how other avian species have fared since the decrease of anthropogenic noise—and we can take on this role by listening to the birds around us.

COVID-19 has generated a multitude of changes in our daily lives that are especially noticeable in urban environments. Previously muffled by the hubbub of human civilization, prehistoric melodies can be heard once again: the melodious trills and complex warbles of birdsong.

It may not be long before automobiles crowd the acoustic stage once more. Meanwhile, with noise pollution at historically low levels, we have the opportunity to appreciate our avian neighbors and, more importantly, make space for them to continue performing their primeval repertoires of life.

 

References:

Derryberry, E. P., Phillips, J. N., Derryberry, G. E., Blum, M. J., & Luther, D. (2020). Singing in a silent spring: Birds respond to a half-century soundscape reversion during the COVID-19 shutdown. Science, 370(6516), 575–579. https://doi.org/10.1126/science.abd5777

Luther, D. A., Phillips, J., & Derryberry, E. P. (2015). Not so sexy in the city: urban birds adjust songs to noise but compromise vocal performance. Behavioral Ecology, 27(1), 332–340. https://doi.org/10.1093/beheco/arv162

Nemeth, E., Pieretti, N., Zollinger, S. A., Geberzahn, N., Partecke, J., Miranda, A. C., & Brumm, H. (2013). Bird song and anthropogenic noise: vocal constraints may explain why birds sing higher-frequency songs in cities. Proceedings of the Royal Society B: Biological Sciences, 280(1754), 20122798. https://doi.org/10.1098/rspb.2012.2798

When the pandemic quieted San Francisco, these birds could hear each other sing. (2020, September 24). National Geographic. https://www.nationalgeographic.com/animals/2020/09/pandemic-san-francisco-birds-song-improved/

File:White-crowned Sparrow 2.jpg. (2008, August 22). [Photograph]. Wikimedia Commons. https://commons.wikimedia.org/wiki/File:White-crowned_Sparrow_2.jpg