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Human Noise Pollution Changes Bird Behavior Patterns, According to Cal Poly Study

February 16, 2015

western scrub jay
Western scrub jay © Jarek Tuszynski / Wikimedia Commons / CC-BY-SA-3.0 & GDFL


Human-made noise is more than annoying for a variety of bird species — it's changing their behavior in profound ways. A Cal Poly study published in the journal Global Change Biology reveals that the song, diet and foraging location of birds in Europe, North America and the Caribbean can be predicted based on human-made background noise.

"Ten years ago, we would have thought that animals habituate to these sounds and that was the end of the story, but other organisms live in completely different perceptual worlds from humans," said Clinton Francis, a biology professor and author of the study. "Slight changes might compromise their ability to perform essential functions, such as detecting a predator or finding food."

Compiling data from 14 studies in Europe and North America, Francis found that birds with high-pitched songs at frequencies above those of human noise fared well near busy roads, but those with lower-pitched songs left that area. Predatory birds were also less numerous near roads. Although the exact reason is unknown, Francis suspects that it is because they couldn't hear their prey.

"We're interfering with birds' ability to hear important sounds," Francis said. "Imagine walking around in a thick fog. Birds in a noisy area can only perceive the world several meters at a time."

The redistribution of bird populations can have serious and long-lasting effects on ecosystems. For example, western scrub jays in New Mexico hide 4,000 seeds in multiple locations every year to help them survive the winter. The seeds they don't find become the next generation of piñon pine trees.

In an earlier study, Francis found that scrub jays aren't caching seeds in noisy areas near oil and gas drilling operations and piñon pine seedlings are also less common in these areas. Because the life span of a piñon pine can reach over 350 years, the full effects of noise pollution won't be known for decades.

Eighty percent of the U.S. has human-made background noise, according to a study from the National Park Service. "We're making a lot of places unsuitable for bird habitation that would probably otherwise be fine," Francis said.

Francis points out that there are possible solutions to noise pollution, such as not using leaf blowers, making sure car mufflers function correctly, and using noise-dampening road surfaces. "We can change the sensory environment for the better," he said.

Read the highlight on NBC News

View coverage of Francis' research on NBC News

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