People around the world are reporting that birds are much louder these days.
But Sue Anne Zollinger, an ornithologist from Manchester Metropolitan University, cautions: Don't believe everything you hear.
With the decrease in traffic, there's less noise pollution. That means birds have less noise to compete with, she says. (Scroll down to the end of this story to listen for yourself.)
"Although our perception might be that they're singing louder, it's actually likely in places that are typically noisy that they're singing more quietly than normal," Zollinger said in an interview with Morning Edition. "But when the noise is gone, they're probably singing quieter than they do normally."
In other words, birds are like us: In a noisy bar, for example, people will raise their voices.
Zollinger says that idea gels with current research on bird noise patterns.
"We know from some earlier studies in the city of Berlin that birds sing quieter on the weekend mornings during the time that's normally rush hour than they do during rush hour during the week because the noise levels are lower," she said. "And that's probably what's happening now."
She tested people's observations that birds are louder during a time of city lockdowns and self-isolation. Zollinger, who lives near an airport in Manchester, England, recorded the call of a songbird known as a chiffchaff.
She found that the chiffchaff's song almost doubled in its decibel level when there was the sound of aircraft in the background of the audio, compared to the absence of aircraft noise.
Listen to the audio clips below to see if you can hear the difference.
DAVID GREENE, HOST:
With life at a standstill, have you noticed birds singing more? Seems to be happening all over the world. So we called Sue Anne Zollinger. She's an ornithologist at Manchester Metropolitan University in the U.K. And I asked her what's going on.
SUE ANNE ZOLLINGER: Actually, although our perception might be that they're singing louder, it's actually likely, in noisy - places that are typically noisy that they're singing more quietly than normal, because this increased level of background noise, like it does for us if we're standing on a noisy street corner or in a noisy bar, they would normally elevate how loud they're communicating or their song levels. And when the noise is gone, they're probably singing quieter than they do normally.
GREENE: Oh, that's crazy. So you're saying that we might think that they're singing more loudly because we're noticing it more. But in this climate, it might actually be the opposite. They have less noise to compete with.
ZOLLINGER: That's right. We know from some earlier studies in the city of Berlin that birds sing quieter on the weekend mornings during the time that's normally rush hour than they do during rush hour during the week because the noise levels are lower. And that's probably what's happening now.
GREENE: So I was told by my colleagues that you brought us some sound that you wanted to play for us. Can you start off by telling me exactly what it is and where you gathered this audio?
ZOLLINGER: So I live fairly close to the airport. And so when I'm out walking my dog on my one walk a day (laugher), I recorded birds there. It's usually really noisy there. And now there's very few airline traffic. So the bird in the recording is a chiffchaff. And in the first recording, he's singing without any background noise. And in the second recording, he's singing while a airplane goes overhead.
(SOUNDBITE OF CHIFFCHAFF CHIRPING)
GREENE: OK. And then we're going to hear with the sound of airplane noise that's more common in this area.
(SOUNDBITE OF PLANE FLYING, CHIFFCHAFF CHIRPING)
GREENE: Wow. I totally see what you mean. Without the extra noise, it sounds like they're singing more loudly because I'm noticing it more. But you're saying we're hearing something that's in the opposite direction.
ZOLLINGER: Yeah, exactly. So in the recording when there's no background noise, the bird's singing about 60 decibel, measured at where I was standing, which was about six meters or six yards away from the bird. And when the plane goes over, he kind of almost doubles how loud he's singing.
GREENE: So you spend a lot of time, obviously, studying nature. Do you think we'll have a different relationship with nature or a different appreciation as we emerge from this crisis?
ZOLLINGER: I think we tend to take it for granted or undervalue it. And it's a nice time, when everything stops, to realize how it's there. And it's even there in the cities. And we often don't see it because we're there. And we're busy. And we're doing what we're doing, rushing around being humans. And that when we pause all of that stuff, we start to see this kind of activity that's kind of going on around us.
GREENE: Sue Anne Zollinger is an ornithologist at Manchester University in the U.K. Thanks so much.
ZOLLINGER: My pleasure.
(SOUNDBITE OF ANDREW BIRD'S "LIT FROM UNDERNEATH") Transcript provided by NPR, Copyright NPR.