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When the world shut down because of the Covid-19 pandemic, the world suddenly became quieter. Birds were singing more quietly, too. Scientists found that birdsongs, particularly those of the white-crowned sparrows in San Francisco, California, became softer and more complex during the shutdown.
How has noise pollution affected the birds?
Before the pandemic, scientists had been studying the sparrows in the city for years. In a study done in 2016, they found that noise from traffic and machines like air conditioners caused the birds to sing more loudly and shrilly. Because the birds had to scream to be heard above all the noise of the city, it affected their lives in negative ways, such as:
• Birdsongs got louder and had less pitch variation, which meant that they were less effective in attracting mates and competing with rivals.
• Birds got stressed singing in noisy environments. They aged faster and their metabolisms were disrupted because of this.
• In a noisy environment, birds also found it hard to listen to their babies and other birds who might be communicating with them, such as those warning of a predator nearby.
• Bird diversity also declined because other birds who could not adapt to the noisy environment moved out of the city.
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Why did birdsongs become softer and more complex?
With the pandemic shutdown, noise pollution in the city decreased. There were fewer cars on the streets, so traffic noise was reduced. People were in their homes and not on the streets chattering, and loud and noisy human activities like construction, concerts, and parties stopped. In fact, scientists found that the noise level was like what it was in the city in the 1950s. It was like the shutdown erased 50 years of noise from the city!
Without having to compete with all the noise of the city, the scientists found that birdsongs became 30% softer and had a wider range of pitch variation compared to the songs before the pandemic shutdown. The songs also carried more information and traveled farther compared to those before the shutdown.
What does this mean for the birds?
The scientists think that the results of their study are good news for the birds. The greater pitch range is good for the birds’ mating potential, since female birds find this more attractive. The change in their songs also proves that the birds can quickly adapt to their changing environment. After their study, the scientists realized that making cities less noisy could have a great impact on the birds. Aside from improving their songs, it could also help other birds return and increase the population diversity in urban areas.
After reading the passage, answer the following questions:
- What happened to birdsongs because of the Covid-19 shutdown?
- They became softer and more attractive.
- They became longer.
- They became louder.
- They stopped altogether.
- How has noise pollution affected the birds?
- Birdsongs got louder and had less pitch variation.
- Birds got stressed singing in noisy environments, they aged faster, and their metabolisms were disrupted.
- Birds found it hard to hear their babies and other birds communicating with them.
- All of the above
- Why was there reduced noise pollution during the shutdown?
- There were fewer cars on the streets, so traffic noise was reduced.
- People were in their homes and not on the streets chattering.
- Loud and noisy human activities stopped.
- All of the above
- According to the scientists, what is another benefit of reduced noise pollution to the birds?
- The birds can find food more easily.
- Other birds can return to the cities and increase the population diversity there.
- The birds can fly higher.
- The birds can hear people more clearly.