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January 27, 2022

Ecologists use sound to study landscape health

By Mali Wiederkehr | March 31, 2011

For centuries, biologists have been fascinated with studying the role of animal sounds. In many animal species, sounds play a crucial role in communication and behavior. A recently introduced field of science known as soundscape ecology calls to study not just individual animal sounds, but the collective sounds of ecosystems.

The push to study ecosystem sounds hinges on the idea that sounds can determine ecosystem health. Bryan Pijanowski, a professor in the department of forestry and natural resources at Purdue University is one of the scientists who believe that the study of soundscape ecology should be formalized.

“We’re interested in all the voices of the landscape. Not just particular individual species, but really, the orchestration of those different sounds by biological organisms,” Pijanowski told National Public Radio.

The importance of soundscape ecology is illustrated by the trumpeting of forest elephants in the middle of the night. In addition to the trumpeting, “we’re also hearing some other sounds — the crickets and occasional bird and maybe some other things in the background here,” Pijanowski said.

A recording of the various sounds shows how animals partition the soundscape: the insects comprise high frequency while the elephants dominate the lower frequency sounds. Another example is the sounds that ants make when they rub their bodies against one another as a form of communication known as stridulation. Though it is too quiet for humans to hear, stridulation is crucial to ant communication.

“One of the main points we’re trying to make here is that a soundscape can be something that we humans just don’t hear,” said Pijanowski. “It can be on a fairly small scale.”

These animal sounds are crucial because they shed light on animal interaction within a particular species as well as across different species. For instance, some newts follow frog sounds in search of the best ponds for breeding. Pijanowski believes that these sounds are equally important to the environment’s health as are trees and ponds.

A major question that this research

generates is to what extent human sounds impact the soundscape.

Jesse Barber, an assistant professor of biological sciences at Boise State University, said that the most relevant example of human noise affecting animals is the prevalence of certain bird species near oil and gas fields. He found that birds typically gave birth to fewer offspring and that species were less diversified near the noisy machinery than in a similar, yet quiet, environment.

“There is significantly reduced species richness comparing these two sites,” Barber told National Public Radio.

Similarly, research in Germany has shown that noise interferes with bats’ ability to search for insects on the ground, which they normally locate by listening to the insects move.

“Most land management agencies don’t consider noise when they’re making decisions about how to manage public resources,” Barber said. “Even biologists, on the more basic level, haven’t thought about how it’s all integrated.”

Soundscape Ecology has the potential to significantly impact the way we approach the environment’s health in regards to noise.

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