Dave Keeling

Is Constant Human Noise Stressing Out Wildlife?

By Jason Daley

A major study earlier this year showed something incredible. Looking at 492 protected areas in the U.S., researchers found that 62 percent of the parks, wilderness areas and green spaces were twice as loud as they should be. About 21 percent were 10 times as loud. Noise isn't just annoying—chronic exposure to traffic, generators and airplanes can lead to negative consequences for wildlife. Researchers like Nathan Kliest are just getting a handle on exactly how all that noise impacts animals. Kliest, formerly of the University of Colorado Boulder and now at SUNY Brockport, recently investigated the impact of chronic noise on birds in the Southwest.

Kleist and his colleagues found that a perfect experiment was already underway in the San Juan Basin of northern New Mexico. While much of the area is owned by the Bureau of Land Management and is uninhabited, the piñon and juniper flats are dotted with gas-extraction wells. While some of the wells run more or less silently, others have very loud compressors that emit a nonstop hum in a range that overlaps with the frequency of many bird vocalizations.

In a previous study, researchers had already looked at how the noise from these compressors affects birds, finding that the constant hum altered which birds nested in the nearby area. Noise-tolerant species moved closer to the sites while more sensitive species fled the area. But Kleist wanted to examine the physiological effects of noise pollution on the birds.

He built 240 nest boxes by hand and placed them at 12 pairs of gas wells in the Rattlesnake Canyon Habitat Management Area. One site in each pair had a droning compressor while the other was more silent. Then, over the course of three years, he monitored three cavity-nesting species that used the boxes: the western bluebird, the mountain bluebird and the ash-throated flycatcher. Kleist collected blood samples from adult female birds and chicks and assessed the body size and feather length of nestlings each breeding season.

The results, reported in The Proceedings of the National Academy of Sciences, showed that mountain bluebirds avoided the noisy areas, and flycatchers also kept their distance, though they were a little more tolerant. Western bluebirds, however, seemed fine with increased noise levels and nested everywhere on the sites. But that doesn't mean they were unaffected. Nestlings in high-noise areas had smaller body sizes and reduced feather growth.

So why would a bird choose to nest in a noisy area? Researchers aren't certain, but it's possible some birds are attracted to noise because it keeps away predators and other species competing for resources, creating an exploitable niche. While this might be an evolutionary advantage under normal circumstances, it could be an "ecological trap" when it comes to human-generated noise, leading the birds to make harmful choices.

Kleist said it's possible that the drone of the compressor drowns out the calls of other birds, which mother bluebirds rely on to tell them whether predators like scrub jays and bobcats are present. "It's possible birds in loud habitats have less perception and knowledge of their environment and have to spend more time and energy figuring out what is going on," he said. "A mother bird in a loud box might be leaving the nest box more often and might not be brooding as much so the temperature wavers."

The team also found something unexpected: All the birds nesting in noisy areas had lower baseline levels of corticosterone, a key stress hormone. "I was really surprised," said Kleist, who thought the birds' stress hormones would be through the roof. "I saw these decreasing baseline stress hormones while seeing decreasing reproductive and hatching success in western bluebirds. It was a juxtaposition of results I didn't expect."

But the result made sense to Christopher Lowry, a stress physiologist at CU Boulder and coauthor of the paper. "You might assume this means they are not stressed. But what we are learning from both human and rodent research is that, with inescapable stressors, including post-traumatic stress disorder in humans, stress hormones are often chronically low," he said in a statement. Stress leads to hypervigilence or the "fight or flight response." However, most organisms cannot sustain that heightened state for very long. So the body down-regulates stress hormones to conserve resources, leading to hypocorticism, which causes increased inflammation and reduced weight gain, at least in tests on rats.

"That's an insight into conservation physiology that his study tightens," said Kleist. "These results are maddeningly all over place. But any disregulation suggests chronic stress."

There is still a lot to work out about how exactly noise impacts wildlife and human health, but Kleist said there's mounting evidence that it's an element policymakers and land managers need to begin thinking about. "Noise might not be good for wildlife or humans. It reduces the value of habitats like parks," he said. "To make them as valuable and useful as possible to wildlife, we need to consider the impact of noise."

Reposted with permission from our media associate SIERRA Magazine.

Show Comments ()

Those Little Produce Stickers? They’re a Big Waste Problem

By Dan Nosowitz

Those little produce stickers are ubiquitous fruits and vegetables everywhere. But, as CBC notes, they're actually a significant problem despite their small size.

Keep reading... Show less

Despite Trump’s Bluster, U.S. Officials and Scientists Maintain Climate Work with International Partners

Trump has loudly declared his intention to withdraw the U.S. from the Paris agreement, but, behind the tweets and the headlines, U.S. officials and scientists have carried on working with international partners to fight climate change, Reuters reported Wednesday.

Keep reading... Show less
Gina Loudon and administrator of the U.S. Environmental Protection Agency Scott Pruitt speaking at the 2017 Conservative Political Action Conference (CPAC) in National Harbor, Maryland. Gage Skidmore

EPA Sued Over Failure to Release Correspondence With Heartland Institute

The U.S. Environmental Protection Agency (EPA) is being sued for its "unlawful and unreasonable delay" in responding to requests for information about the agency's communications with the Heartland Institute, according to a complaint by the Southern Environmental Law Center (SELC) and the Environmental Defense Fund (EDF).

The Heartland Institute is an Illinois-based think tank that rejects the science of man-made climate change and has received funding from the Koch brothers and the fossil fuel industry.

Keep reading... Show less
Trump Watch
Aerial photo of Duke Energy Coal Ash Spill. Wake Forest University Center for Energy, Environment & Sustainability

Trump Administration Seeks to Gut Water Pollution Safeguards, Putting Communities at Risk

By Mary Anne Hitt

A Hollywood scriptwriter couldn't make this up. One day after new data revealed widespread toxic water contamination near coal ash disposal sites, U.S. Environmental Protection Agency (EPA) head Scott Pruitt announced a proposal to repeal the very 2015 EPA safeguards that had required this data to be tracked and released in the first place. Clean water is a basic human right that should never be treated as collateral damage on a corporate balance sheet, but that is exactly what is happening.

Keep reading... Show less
Impossible Foods

Impossible Burger Executive Grilled at Sustainable Foods Summit

An executive from a company selling a genetically engineered meat alternative faced tough questions at the Sustainable Foods Summit held in San Francisco at the end of January.

Keep reading... Show less
Elephant family in Kenya. Nzomo Victor / Flickr

Why Trump’s New Trophy Hunting Council Is a Disaster

By Elly Pepper

In early November—the same week the Trump administration announced its disastrous decision to allow elephant and lion trophy imports from Zimbabwe and Zambia—the administration decided to create an advisory committee, the International Wildlife Conservation Council (IWCC), to advise Trump on how to enhance trophy hunters' ability to hunt internationally.

Yup, that means the administration now has a council dedicated exclusively to promoting the killing of more imperiled species, like elephants and lions, for sport. The council's mandate includes counseling Trump on the economic, conservation, and anti-poaching benefits of trophy hunting, of which there are very few. Sadly, Trump doesn't want advice on the many drawbacks of trophy hunting.

Keep reading... Show less
A robot bee from a season three episode of Black Mirror on Netflix

Walmart Files Patent for Robot Bees

With the mass die-off of bees spelling trouble for agriculture, the world's largest retailer has filed patents for the use of "unmanned vehicles," or drones, to aid with pollination and crop production.

In U.S. Patent Office documents made public last week, Walmart has applied for six patents on drones designed to identify pest damage, spray pesticides and pollinate plants.

Keep reading... Show less
The iconic moai of Easter Island are threatened by erosion caused by rising seas. Aupaelfary / CC-BY-SA 3.0

Climate Change Threatens Easter Island

Easter Island has long served as a reminder of what happens to a civilization when the environment it depends upon collapses. Now, the iconic remains of that civilization are under threat from a new environmental challenge: global climate change.

Easter Island, Rapa Nui in Polynesian, is surrounded by statues called moai situated on top of ahu, or platforms. But according to an in-depth report for The New York Times published Thursday, the moai are now at risk from erosion caused by sea level rise.

Keep reading... Show less


The best of EcoWatch, right in your inbox. Sign up for our email newsletter!