Noise Pollution

Bats have had a bad reputation within the human community for a long time. Deemed as “disease-carrying vermins” and “flying rats,” these animals have been subjected to disgust and given the death sentence by many who lack genuine understanding of them. Bats have been dying by the millions in recent years due to factors such as White-nose Syndrome (WNS), wind turbines, and oncoming traffic. However, one crucial catalyst is often overlooked: noise pollution. 


​​Imagine stepping into a bustling city at night, with faint club music pumping in the background, mingling with the loud honks of passerby cars and the thunderous conversations of pedestrians exploding everywhere. With the advent of electricity and rapid industrialization, nights have gotten longer and cities louder. Noise pollution, defined as any sounds clocking in above 60 decibels, has significantly increased. That includes noises from air or land transportation, construction sites, nightlife, and many other human attributed factors. High noise levels can affect human health, causing respiratory, sleep, behavioral, and memory issues. In bats, the effects are equally devastating. 

Bats utilize a method called echolocation to hunt for prey. They produce “calls” known as ultrasounds—soundwaves that are undetectable to humans—that bounce off of nearby objects and reflect back to them. They then determine where and what the object is and decide whether they should strike. 

A 2013 experiment conducted by Jessie P. Bunkley and others concluded that increased noise level reduces bat activity such as hunting. The experiment implemented compressor machines, which produced “high-intensity compressor noise” or broadband noises, for 24 hours a day, 365 days a year around the testing grounds and monitored bat activities. 

Bunkley and her colleagues observed that bats emitting a soundwave with a frequency of less than 35 kHz became less active and were less present in the area because of the compressor machines placed there. While bat species with soundwave frequencies of over 35 kHz underwent no such change, they did alter their calls to adapt to the compressors. The altered calls, said the researchers, “might affect prey detection,” meaning that increased noise levels and altered ultrasounds may render the bats less efficient in hunting for food and, as a result, decrease their food intake. 

 

Fewer bats now roam in the wild, and the sharp decline in bat population by the millions may be harmful to humans as well. Similar to birds and bees, bats act as a natural pollinator and help crop reproduction. Additionally, they are great contributors to pest control as they eat the insects that feast on crops. Studies have shown that bats alone prevent more than $1 billion per year in crop damage. Evidently, bats are an essential contributor to human society both ecologically and economically.  

Luckily, we can reduce noise pollution fairly easily. By putting up soundproof insulation, working during the day, and reducing nightlife activities, we can aid in the survival of bat species and save these important members of the ecosystem. 
 

Sources
Brookshire, Bethany. “5 Reasons You Might Be Seeing More Wildlife during the COVID-19 Pandemic.” Science News, 5 June 2020. 
Bunkley, Jessie P., et al. “Anthropogenic Noise Alters Bat Activity Levels and Echolocation Calls.” Global Ecology and Conservation, Elsevier, 8 Nov. 2014. 
“Echolocation.” National Parks Service, U.S. Department of the Interior.