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  • [♪ INTRO]

  • In 2001, shortly after the September 11th attacks in the United States,

  • something strange happened to a group of whales near eastern Canada:

  • They relaxed.

  • Specifically, researchers found lower levels of stress-related hormones in their poop,

  • which is apparently how you measure these things.

  • And this didn't seem to be a coincidence.

  • In fact, after more observations, there seemed to be an obvious cause:

  • Right after 9/11, the waters off the east coast of North America were quiet.

  • There were fewer ships than normal,

  • and the whales appeared to let out a collective sigh of relief.

  • At least, figuratively.

  • This study was pretty famous when it finally came out in 2012,

  • but it's not an isolated case.

  • Across the world, scientists keep realizing that the noise we make

  • is affecting even the farthest, most remote corners of the world,

  • and is impacting everything from owls to dolphins to plants.

  • But thankfully, by learning what all this sound does,

  • we can hopefully learn to keep it under control.

  • Noise pollution is noise created by human activity.

  • It's mostly associated with transportation,

  • since vehicles can create a constant hum anywhere humans are doing their thing.

  • But technically, it can be any human-made noise

  • that interferes with nature's normal activities,

  • including outdoor concerts and the hum of air conditioners.

  • Your A/C unit might not seem like a big deal to you, but in many areas,

  • the level of noise we make is becoming excessive.

  • And that comes with consequences.

  • For one, it's disrupting how animals use sound to communicate.

  • Vocal communication, like chirps, grunts, and songs,

  • is key between individuals within a species.

  • And for many, it's the primary way to find a mate.

  • Like, I don't know if you've been outside in the spring,

  • but it's kind of hard to not notice the eruption of flirty bird songs that hits

  • once warm weather rolls around.

  • Yes, we get it! You want to mate with somebody!

  • The problem is, if you want to use sound to communicate,

  • you need to actually get the message.

  • And for many animals, that's becoming harder.

  • For instance, one 2016 study on birds played a recording of traffic sounds,

  • along with the occasional lawn mower or airplane flyover noise.

  • Then, on top of that, they played a recording of a bird's alarm call.

  • Normally, birds would chime in and respond to this.

  • But in the study, the number of responses was 80 percent lower than expected.

  • And it wasn't just that the birds weren't responding:

  • They didn't adjust their foraging behavior in these areas, either.

  • That's kind of significant, because if you can't hear a warning call or don't understand it,

  • you might be the last to know about a predator, or an oncoming bus.

  • Meanwhile, another paper published that year

  • looked at how noise pollution affects hunting.

  • And it found equally concerning results.

  • This team tracked the foraging activities of 78 short-eared and long-eared owls.

  • And they found that low levels of traffic noise

  • impacted the birds' ability to detect prey more than 120 meters from roadways.

  • At first, that might not seem so bad.

  • Like, maybe owls just shouldn't look for dinner at the side of the road.

  • Except, it turns out, a lot of our land these days isat the side of the road.”

  • A 2003 study measured the proportion of land within reach of roadways,

  • looking at more than 150 ecoregions

  • and more than 2000 watersheds across the United States.

  • It found that 20 percent of the total land area surveyed

  • was within about 120 meters of a road.

  • So, suddenly, a quiet hunting ground seems a lot harder to come by,

  • especially if you figure the number of roads has only gone up since 2003.

  • And when you think of the delicate balance of predator-prey interactions,

  • it's not like this sound just impacts hungry owls.

  • It could impact their entire ecosystems.

  • Now, you might think that at least some areas are immune to noise pollution.

  • Like, it couldn't be a problem, say, way out in the open ocean, right?

  • Well, I've got some bad news for you.

  • Even though there isn't as much traffic in the open seas,

  • there's still a whole lot of noise.

  • The movement of ships creates enormous amounts of sound at low frequencies;

  • frequencies that travel efficiently through water and cover great distances.

  • And on top of that constant transportation,

  • there are more specific sources of noise pollution, too, like resource extraction.

  • Extracting oil and gas can actually be some

  • seven orders of magnitude louder than the loudest ship noises.

  • They're so loud, in fact, that one researcher reported

  • they can hear extraction happening near Brazil off the coast of Virginia.

  • So even in areas that might seem peaceful,

  • there's more than enough sound to be disruptive. And it is!

  • In 2016, researchers from the University of Maryland

  • recorded a group of dolphins near coastal shipping lanes.

  • And they discovered that, when ship activity

  • elevated the ambient noise in the waters, the dolphins used shorter calls.

  • Probably so they could actually get their message across.

  • One marine biologist on the project, Dr. Helen Bailey,

  • compared the dolphins' situation to someone trying to order in a noisy bar.

  • “I'll have fries with my burger, please.”

  • “I said I'll have mine with fries, thanks.”

  • WITH. FRIES.”

  • Although more research needs to be done to understand the impact of all this,

  • it's possible that these simplified communications could impact social bonding.

  • Kind of like a noisy bar might.

  • And since dolphins are such a social species, that could be significant.

  • So, from land to sea, noise is changing the way animals behave.

  • But sometimes, animals just don't want to deal with all this.

  • Sometimes, instead of adapting to shorter calls or different hunting spots,

  • they decide to avoid noisy areas entirely.

  • One study that got really into the weeds about this

  • was conducted by researchers at Boise State University in 2012.

  • They knew that, when studying noise pollution,

  • it can be really difficult to separate all the variables at play.

  • Like, think about traffic.

  • Unless you're careful about your study design, it can be hard to figure out

  • if it's just vehicle noise that's disrupting animal behavior.

  • It could be a number of other things, too, like street lamps, vehicle collisions, or air quality.

  • So, to try to separate things out and really figure out how noise disturbs species,

  • these researchers set up a “Phantom Road.”

  • They picked a stretch of wilderness far from actual roads,

  • and set up 15 pairs of speakers along a half-kilometer path.

  • Then, they played traffic noises.

  • But not like, sounds from a five-lane freeway.

  • They played traffic sounds recorded in Montana's Glacier National Park,

  • where only 12 cars go by every minute.

  • And! What do you know?

  • This audio-only experiment still resulted in

  • more than a 25 percent decline in migratory bird abundance in the area.

  • A couple of species even avoided the Phantom Road entirely.

  • That's not an easy situation for migratory birds to be in,

  • considering that it's already an incredibly dangerous time of year for them.

  • Adequate migration stopovers are already disappearing for other reasons, too,

  • and now, we're starting to understand how sound

  • is further limiting the areas they can rest and feed.

  • While I've been talking about these studies,

  • you might have noticed that the amount of noise pollution

  • has really varied from paper to paper.

  • Like, there's a big difference between the sound of

  • 12 cars a minute and a roaring lawn mower.

  • That's because the amount of noise that affects wildlife tends to vary from species to species.

  • The amount of sound that bothers a migratory bird might not affect a dolphin as much.

  • And that's what makes it hard to draw a line in the sand and say,

  • Well, if we can only reduce noise pollution by this amount, animals will be okay.”

  • Instead, scientists have to roll up their sleeves and look at things on a case-by-case basis.

  • Because the effects of noise pollution can really vary.

  • Like, in one study, scientists collected wood frogs

  • from ponds around one to five kilometers from the nearest major road;

  • relatively quiet areas that got only moderate amounts of traffic noise.

  • These frogs were then exposed to traffic noises in the lab

  • and showed increased levels of stress hormones.

  • Shifting from a quiet pond to noise pollution exposure affected their immune systems

  • and impacted their ability to make antimicrobial compounds for their skin;

  • compounds that are an important defense against pathogens.

  • On the other hand, wood frogs raised in noisy ponds,

  • those that were less than a kilometer from the nearest road,

  • had a suppressed stress response to traffic noise exposure in the lab.

  • And in some ways, that's great!

  • It means they can tolerate the noise pollution better.

  • But it might also mean these frogs have a generally suppressed stress response,

  • which could make them less wary about things like predators.

  • There are numerous other examples like this,

  • for both animals on land and in the ocean.

  • And it makes research on individual species really important.

  • But even while scientists are honing in on those individual effects,

  • they're also realizing there's a much bigger picture here:

  • that this type of pollution might be changing how ecosystems function as a whole, too.

  • It might even affect plants.

  • Take the results of a 2012 study, for example.

  • It took place in an area that's noisy even by human standards.

  • It had a high density of noisy natural gas wells

  • and compressors creating sounds over 95 decibels;

  • enough to cause hearing damage in humans over long periods of time.

  • This noise had driven birds called western scrub jays from their habitat.

  • And while that was good for some species,

  • like hummingbirds, whose nestlings are preyed upon by the scrub jays,

  • it was bad for the area as a whole.

  • And it was because the scrub jays were important seed dispersers.

  • Specifically, they helped spread the seedlings of the piñon pine.

  • So without them, fewer pines.

  • In fact, the change was so dramatic

  • that these trees were four times more abundant in quiet areas.

  • That meant more shade, more oxygen,

  • and more habitats for all the species that called them home.

  • All because of a little quiet.

  • So, from dolphins in the ocean to owls in the sky to entire forest ecosystems,

  • there's a lot happening here.

  • But the good news is, there's also plenty of room to end on a hopeful note.

  • Because there are a bunch of steps we can take

  • to cut down on the amount of sound we're putting into the world.

  • For example, in some protected areas,

  • shuttle services have already been implemented to cut down on traffic.

  • There's also some effort being made to align aircraft flight patterns with roads,

  • which would limit noise to more specific corridors and cut down on how far sound spreads.

  • Navies around the world have also done research on how to make ships quieter,

  • and research vessels today are much quieter than earlier ships.

  • So now, new tech is being developed to make oil and gas operations quieter, too.

  • There are even changes we can make in our daily lives

  • to cut down on the racket we're creating.

  • Our modes of transportation, the industries we support,

  • how we work and play in natural spaces,

  • all these things have an impact on the sound we put out every day.

  • Again, this won't solve everything,

  • because some species are impacted by even tiny amounts of artificial noise.

  • But as we better understand these problems and their effects,

  • we'll at least be able to make some compromises to bring back a little peace and quiet.

  • Thanks for watching this episode of SciShow!

  • If you want to learn more about noise pollution, you're in luck,

  • because we've got a whole separate video about how it affects humans.

  • Just in case you thought we were spared from the perils of noise.

  • If you watch it, let us know what you think!

  • [♪ OUTRO]

[♪ INTRO]

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