As many said at the time, the Bird Song would have sounded different during lockdown, according to a scientific study.
By analyzing bird calls recorded over decades, scientists confirmed a change in the birds’ acoustic repertoire as the city calmed down.
The birds raised the quality of their songs, as they chanted to defend their territory and entice their companion.
And while it might sound to human ears that the bird song was louder, in reality the birds were singing more quietly.
These gentler, more gentle songs were carried over due to no background noise.
Dr. Elizabeth DeBerry of the Department of Ecology and Evolutionary Biology at the University of Tennessee in Knoxville, USA for years has studied how noise pollution affects bird song.
She told BBC News: “People were right that the birds’ sounds were different during the lockdown and filled the sound scene that we had basically abandoned.”
“As we walk out of the sound scene, the birds have moved on and I think this tells us something about how much we have been affecting bird noise and communication, especially in cities.”
What did the study show?
Thanks to a long-term study of white-crowned bird songs living in and around the San Francisco Bay Area, scientists were able to compare the effects before and during the lockdown.
What they found was a bit surprising. Most of the time, male sparrows sing, and during silence the birds improved their vocal performance and sang songs of less capacity to defend their territory and attract a female.
“When the noise levels decreased during the lockdown, their songs sounded sexier for the other birds in the population,” said Dr Derby.
She added that it shows how quickly nature can recover from the effects of human noise pollution.
“This study shows that when noise pollution is reduced, there is an almost instantaneous effect on wildlife behavior and this is really exciting because many of the things we do to try to help the environment take a long time to improve.
The shutdown was actually a natural experiment in how wildlife responds to human-induced noise.
Traffic levels across the Golden Gate Bridge fell to similar levels in the 1950s, and it was reported on social media that coyotes were seen wandering around.
Much has been written about the relationship people felt with nature during lockdown. This study provides some evidence that both wildlife and humans have benefited from the “Silent Spring”.
“It improves your personal condition and mental health to be able to hear more birds and I think the lockdown highlighted that, and this study provided some data to support that,” said Dr. DeBerry.
What do we know about sparrow songs?
The white-crowned sparrow, with distinct black and white stripes, is found throughout most of the United States and Canada, where its songs have been studied extensively.
Different subgenres across the country sing slightly different songs, known for the introduction of sweet whistles, a series of mixed whistles, and a trail near the end.
Sparrows have been recorded in the San Francisco Bay Area since the 1970s, creating a rare historical record of song behavior.
It is well known that city-dwelling birds have had to modify their songs in recent decades, just like people who have to speak louder at a crowded party. Scientifically known as the Lombard effect, or the cocktail party effect.
The study, published in the journal Science, was conducted in collaboration with experts at Texas A&M University-San Antonio and George Mason University, Fairfax.
Follow Helen Twitter.