ARI SHAPIRO, HOST:
Life on lockdown inside our homes might be noisy. Outside, the streets and skies are noticeably quieter, and because there's less human sound out there, many people are hearing more wildlife. As Invisibilia's Abby Wendle reports, the relationship between human noise and the rest of nature is often discordant. So is our quiet in this moment having any impact?
ABBY WENDLE, BYLINE: The Internet is humming with rumors of animals reclaiming cities and towns. Dolphins are allegedly swimming in Venetian canals, black bears are supposedly raiding trash cans in LA, and mountain goats have been seen descending the Welsh hills to stroll through town. Some of these quarantine silver lining stories have been debunked, though for now, at least, the goats seem legit. But other anecdotes about nature being more present in the absence of humans come from reliable sources. NPR's own Eleanor Beardsley observed, for the first time in years, birds singing throughout Paris.
ELEANOR BEARDSLEY, BYLINE: But what really blew my mind is I'm sitting by the Seine River right now on a sunny evening, and I just heard a river bird - like, egrets on poles and stuff.
(SOUNDBITE OF BIRD CALLING)
BEARDSLEY: Is that not wild? I have never heard that before.
BERNIE KRAUSE: Yeah. We can hear subtlety of life around us that we haven't heard in a long, long time.
WENDLE: This is Bernie Krause, one of the founders of a field called soundscape ecology that studies how all the sounds in an ecosystem interact with each other and with us. Krause has been recording the natural world for more than 50 years, and in that time he's observed lots of ways our noise is disruptive to wildlife.
KRAUSE: Let's see if I have the frogs and jet flyover.
WENDLE: He tells this one story of how, back in the 1990s, he was recording thousands of frogs that gather in the spring at Mono Lake in California and croak in unison.
(SOUNDBITE OF FROGS CROAKING)
KRAUSE: Notice how they sound really big.
WENDLE: Almost like all the little frogs have joined together to become one giant frog. It's actually a defense mechanism - helps keep predators from locating and attacking individual frogs. But Krause says the military started doing test flights over Mono Basin, and the roar of the jets would cause the frogs to fall out of sync.
(SOUNDBITE OF FROGS CROAKING)
KRAUSE: They would take, like, 45 minutes before they could get in sync again. And during that period of time, we watched as a couple of great horned owls and a coyote came in and picked off a couple of frogs.
WENDLE: Eventually, this led to significant population decline all because of a jet. But Krause says it's not just jets. It's helicopters and chainsaws and tractors and traffic.
KRAUSE: I mean, just endless amounts of noise.
WENDLE: Until now. With billions of people stuck inside, our noise print is dramatically quieter. In Paris, for instance, a group that monitors noise pollution saw as much as a 90% drop in human sounds since the city went on lockdown. So how is this relative quiet impacting wildlife?
MEGAN GALL: There was a question trending on Google. Are birds singing louder?
WENDLE: This is Megan Gall, a sensory ecologist and professor at Vassar College.
GALL: If anything, I would actually guess that the birds are not singing as loud.
WENDLE: That's because, Gall says, they aren't having to compete against human sound, which could be a good thing for the birds.
(SOUNDBITE OF BIRD CALLING)
WENDLE: For one thing, Gall explains, noise has been shown to increase stress hormone responses in birds, which affects immune function. So less noise right now might equal less illness. Plus, birds living in bustling cities or even busy suburban neighborhoods have to expend a lot of energy singing louder. So now that things are quieter, she says the birds might have extra energy to use on different things.
GALL: Like spending time foraging, saving energy to feed your kids, et cetera. So possibly, we'll see animals that have larger broods or healthier offspring. You might also get changes in how females are selecting mates. Now, a lot of that's speculation, of course, but I think there's a lot of really interesting things that could be happening.
WENDLE: While how this all plays out for wildlife is, for the time being, left to informed speculation, one impact of our stillness is ringing clear as a bell.
So the Earth is, like, literally humming underneath of our feet.
ANDY FRASSETTO: That's right. Yep.
WENDLE: Andy Frassetto a seismologist who recently observed, along with colleagues in Brussels and California, a huge drop in human-caused vibrations on the Earth's crust.
FRASSETTO: It was impressive. It was just a reminder that we as a civilization have a noticeable imprint on the world in ways that, sometimes, we don't appreciate.
WENDLE: I, for one, did not appreciate that humans rattle the earth like a tiny earthquake, but we do, mostly from transportation. Automobiles, planes, trains, even our walking registers on seismographs as a kind of constant static. And now that static is way less noisy, giving seismologists a unique opportunity to perhaps detect more subtle vibrations that usually get drowned out, like the ones coming from inside volcanoes close to cities.
FRASSETTO: I think it's an open question how strong this change is, but it's something that I know people in the seismology community are really interested in exploring.
WENDLE: And some scientists are attempting to measure this strange and profound sonic experiment above ground. The Silent Cities project is a call for scientists, journalists, artists, really anyone with good enough audio equipment to record what they're hearing while stuck at home.
AMANDINE GASC: To me, it's very peaceful to walk and, like, able to, like, hear the teeny tiny sounds.
WENDLE: Amandine Gasc is a soundscape ecologist in southern France who helped create the project.
GASC: Like insects moving in leaves, for example, buzzing in the flowers - also, it's spring right now, so it increase also the noise, the wildlife sounds you can hear.
WENDLE: So far, participants are recording at 161 locations all over the world, and the data - an expected 35,000 hours or more of audio - will be available for any researcher who wants to analyze it in the future. Listening to our new sound environment is not just for researchers, though. Ecologist Megan Gall says it can be for everyone.
GALL: One of the potentially positive things that could come out of this is that people are having a chance to interact with the world around them in a way that they maybe haven't interacted with it before.
WENDLE: And those interactions could lead people like Eleanor Beardsley to not only consider the wildlife around them now - the birds singing on the Seine - but help them keep it in mind as things get back to being noisier.
BEARDSLEY: It makes me feel like they're here, and we don't pay attention to them. And we need to because they deserve to have the city as well. It's their land, too.
(SOUNDBITE OF BIRD CALLING)
BEARDSLEY: There he goes. Isn't he cute?
WENDLE: Yes, he is. In this incredibly scary and overwhelming time, he's a refuge.
(SOUNDBITE OF BIRD CALLING)
SHAPIRO: That's Abby Wendle. The new season of NPR's Invisibilia is out now. You can hear it wherever you listen to podcasts.
[POST-BROADCAST CORRECTION: This report incorrectly refers to Great Basin spadefoot toads at Mono Lake as frogs.]
(SOUNDBITE OF THE BOOKS SONG, "CELLO SONG") Transcript provided by NPR, Copyright NPR.
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