Scientific studies have shown that many people said at the time that the song of the birds sounded different during the lockdown.
By analyzing the birds ’calls recorded over decades, scientists confirmed the change in the bird’s vocal store after the city calmed down.
The birds uttered the quality of their songs, as they called for the protection of their territory and the temptation of a mate.
Although it may seem to the human ear that the song of the birds grew louder, the sparrows sang more quietly.
These sweet, soft songs carry more because of the lack of background sound.
Dr. Elizabeth Deriberi of the Department of Environmental Sciences and Evolutionary Biology at the University of Tennessee in Knoxville, USA, has studied for many years how noise pollution affects the song of birds.
He told BBC News: “People were right that the birds made different noises during the shutdown and they basically filled in the soundscape we left behind.”
“When we move away from the soundscape, the birds move away and I think it says something about how big an impact this has had on us birds and communication, especially in cities.”
What does the study show?
Thanks to a long-term study of white-crowned sparrows living in and around the San Francisco Bay area, scientists were able to compare the effects before and during the lockdown.
They were amazed at what they got. Most of the time, it sings male sparrows and during silence the birds improve their vocal performance and sing low-amplitude “sexier” songs to protect their territory and drown a female.
“While noise levels have dropped during the shutdown, their songs are sounding sexier to other birds in the population,” said Dr. Deriberi. Deriberi says.
He showed how quickly nature could recover from the effects of human noise pollution, he added.
“This study shows that wildlife behavior has an almost immediate effect when you reduce noise pollution and it’s really exciting because we try to do a lot to help us take longer to improve the environment.”
A ‘silent spring’?
The lockdown was effectively a natural test of how wildlife responds to man-made sounds.
Traffic levels on the other side of the Golden Gate Bridge dropped to the level of the 1950s, and there were reports on social media that Coyotes had been spotted wandering around.
Much has been written about the connection people felt with nature during the lockdown. And this study provides some evidence that both wildlife and humans benefited from the “silent spring”.
“It has improved your condition and mental health to be able to hear more birds and I think the shutdown highlighted this and this study provided some information to support it,” says Dr. Deriberi.
What do we know about sparrow songs?
The white-crowned sparrow, with its tasteful white and black head stripes, is found in most parts of the United States and Canada, where its songs have been widely studied.
Different sub-species across the country sing slightly different songs, known for their sweetness, whistle identity, legacy of molten whistle, and a trail near the end.
Sparrows in the San Francisco Bay Area have been recorded since the 1970s, creating a rare historical record of song behavior.
It is well known that the birds that live in the city have had to adjust their songs in recent decades, speaking loudly at crowd parties like many people. This is scientifically known as Lombard, or Cocktail Party Effect.
The study was published in collaboration with experts from Texas A&M University-San Antonio and George Mason University Fairfax.
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