Did COVID-19 Lockdowns Improve Birdsong?

Have you ever been in a crowded restaurant and find yourself speaking loudly in a higher pitch to your friend next to you? That is called the Lombard effect. It occurs when background noise from the environment drowns out noises used to communicate between people. Although, this doesn’t just occur with people. Scientists find this phenomenon with birds as well.

According to researchers, noise pollution from automobile traffic in urban areas emits an increase in low-frequency noise. This causes male birds to sing with higher amplitude and frequency, which in turn decreases their singing performance. When their performance is compromised, this makes birds less noticeable when competing with other male birds for breeding territory and mates. This is different for birds in rural areas, which aren’t as affected by car traffic. 

When COVID-19 caused lockdowns across much of the globe, the regular movement of traffic stopped. It also gave scientists an opportunity to explore the effects of reduced noise on local wild animals. In this study, researchers in San Francisco measured the amplitude and frequency of white-crowned sparrows’ birdsongs in April-May 2020 compared to the same sites in May-June 2015.

When the soundscape wasn’t constantly buzzing from cars, the background noise in urban areas of San Francisco dropped to levels that hadn’t been seen since 1954. There was also a decrease in “ambient noise” in both urban and rural areas, meaning loud, periodic sounds such as planes flying overhead or dogs barking. For the first time in years, urban and rural background noises were similar. 

In response, sparrows in urban areas sang more softly with lower amplitudes. This increased their performance — the authors note that it was possible for humans to hear four times more birds than usual during the lockdowns. This may have helped male birds with territory disputes and mating. In a nutshell, the birds were able to “up their game” after being relieved from the typical urban soundscape of San Francisco — in one site, researchers heard bird songs that hadn’t been recorded since the 1970s! 

Overall, the effects were stronger in urban areas than in rural ones. One of the things researchers were surprised by was the resilience found in urban birds. They found it promising to see how quickly the birds snapped back to earlier behaviors when relieved from the typical urban soundscape. This rapid recovery is important to think about as the world continues to struggle with other environmental stressors such as greenhouse gasses, drought, and other extreme weather patterns. 

The researchers recommend further exploring the effects of COVID-19 on birds and other animals. For example, because juvenile sparrows learn birdsong by mimicking their elders, it would be interesting to see how the 2020 lockdowns impact their culture down the line. Likewise, it’s important to understand how other changes during the lockdown (e.g., reduced emissions) have impacted birds and other wild animals. While the pandemic has had a devastating impact in many ways, it’s nice to know that some other species were able to seize the moment and break out into song.