A new study released this week revealed fascinating changes in bird song as a result of reduced urban car traffic from the COVID-19 pandemic. Traffic slowed to 1954 levels, giving biologists an opportunity to see how birds would respond to a 50+ year step back in time.
To put this in perspective, bird song in urban zones has to carry over background noise that is three times as loud as rural areas.
In the San Francisco Bay Area, scientists compared bird songs from the white-crowned sparrow between 2015 and the start of the shelter-in-place order in March and April 2020. They returned to the same sites and covered four different bird song populations, or dialects.
How did white-crowned sparrows change their behavior? Check out these four discoveries below:
1) Birds doubled their distance of communication. If you think bird songs sound louder now during the pandemic, it might not be your imagination!
2) Bird song stands out more, or is more salient, than it was before, when birds had to adapt to the traffic soundscapes.
3) Traffic noise is lower frequency, so birds had been singing at higher frequency to stand out from the background noise. Without the low frequency background noise, bird songs became lower in pitch.
4) Even after half a century of increased noise, birds are able to rapidly respond to changes in the environment.
There have been a few silver linings to the COVID-19 pandemic, including the rapid return of less urbanized birdsong. California Governor Gavin Newsom’s recent executive order bans the sale of non-zero emission vehicles by 2035. Perhaps in another 50+ years, the roadways will return to a quieter state and birds will be able to sing like they did during this pandemic again.