Blog #202--Noise Pollution Harms Many Species

I lived in an apartment building directly below a major flight path for jet airplanes taking off and landing at a large international airport for a year after veterinary school. I didn’t experience any planes the day I signed the rental agreement, so I was in a big shock once I moved in. People in the area were accustomed to stopping their conversations for 30 seconds or more each time a plane would come overhead because the noise from the jet engines was so loud.

To test how low the planes were flying, I took a small 4” football and threw it into the air. From my vantage point, it appeared the ball came within 10-15 yards of the plane. There may have been more distance between them than that, but not much. The airport didn’t use the same flight patterns all the time, but there was no predictable schedule that I could decipher. Sometimes they arrived in the middle of the night, preventing sleep. I could look out the window and see a large number of planes lining up, one after the other, waiting to land.

To say this arrangement was unnerving is an understatement. But it may have been even harder on my two cats. My dominant male tomcat would have roamed all over a neighborhood if given a chance. But once I moved him into the apartment, he was scared to go to the door and never once asked to go outside. Since cats and many other species hear far better than humans, I can only imagine how painful those airplanes must have been for him. He and I survived, but we were grateful to move once the rental year ended.

People who lived near that airport fought to reduce noise pollution, with some success. The airport became more aware of citizen needs and modified some of its procedures. But putting mufflers on jets is out of the question. Noise pollution continues to persist there many years later.

In recent years, scientists have begun to research the effects of noise on various species. They have concluded that human noise production, not only from planes but also automobiles, oil and gas extraction, mining, military activity and other culprits, has a harmful effect on wildlife behavior, their ability to communicate, and ultimately their survival. Noise avoidance sometimes forces wildlife to change behavior and/or their territories, which initiates a chain reaction creating more competition, fewer food sources and less ability to reproduce.

The sense of hearing, which includes feeling sound vibrations, has been important for species far longer than the sense of sight. Not only does a loud noise scare or otherwise disrupt species, it makes it harder for them to communicate with each other and other species. In other words, they say less and hear less, just like humans experience when living under jet airplane flight paths.

One research experiment in particular was an eye-opener for scientists. Boise State University researchers placed loud speakers on trees in an Idaho forest and broadcast sounds of traffic to test the reaction of migrating birds. Scientists had assumed that sound was just one of several obstacles for other species that live near heavily traveled roads, including road kill, visual observation, habitat destruction and chemical pollution. But bird populations in this experiment were reduced by 1/4 along the pretend road, and some were absent entirely due to sound alone.

Reproduction is essential for all species, and loud noises can disrupt mating calls and availability of potential mates. Male birds may have to sing louder, increasing the pitch or frequency of their sounds in ways that might be less appealing to females. They must also wait until quieter moments to sing their love songs, but females might not be nearby to hear them at those times.

In many species such as frogs and other vertebrates, the pitch of their sound helps broadcast their size; the lower the pitch, the larger the body. But if they are forced to sing louder to be heard, their sound will come out at a higher pitch, which may turn off females. Some birds that live close to busy roads often have fewer eggs, and their offspring may have health issues.

Many species are walking a survival tightrope. They must obtain enough energy through hunting and foraging to survive and reproduce while also protecting themselves from being eaten by other predators. If they must expend more energy to avoid human noises or find sufficient foodstuffs, they might not have enough energy to overcome all the obstacles facing their existence. Even small changes in their habits can adversely affect their balance and thus survivability.

All species are part of an interconnected system of life. If something like noise pollution changes the habits of one species, it has a chain reaction effect on all others that interact with it. Even plants can be harmed by these changes. Plants and trees rely on other species to disperse their seeds so they can grow into replacements for the parent. If noises reduce the number of animals or birds that eat and eventually defecate their seeds in new areas, their survival as a species may suffer.

Whales are capable of hearing and transmitting sounds over vast distances. They rely on this communication, but humans have disrupted their hearing by creating abundant noises in the oceans. Passenger liners, large motorized yachts and speed boats are louder for whales than for people, even if those whales are long distances away. The Scripps Whale Acoustic Lab says that background ocean noise has doubled every decade for the last 60 years.

It is reported that the United States Navy is or has been doing secretive research on sonar and other underwater sound systems that might have military uses. Given the increase in whale beaching in recent years, it is possible these intentional noises are one of the causes. At last report, efforts to stop this experimentation have gone unheeded.

Besides that obvious example, there are things we can do to reduce noise pollution for all species, including humans. Some of these are inexpensive, like changing maritime laws to reduce boat speeds. And there are technologies being studied that can reduce or even cloak external noises. Unfortunately, whenever cost is a factor, those with the most to gain by keeping things the way they are may continue to prevent these modifications.

Maybe they should all live under a landing strip at a major airport. They might be more willing to empathize with the suffering of all species that are impacted by noise pollution.

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