Some birds are so stressed by noise pollution it looks like they have PTSD. By Sarah Kaplan January 9


A western bluebird searches the ground from a perch. (Dave Keeling/California Polytechnic State University


The bluebird didn’t realize what she was getting herself into when she chose her new home, about 75 yards from a natural gas compressor. It was only as the days and weeks wore on that the low whine of machinery started to take a toll. It was harder to hear the sounds of approaching predators, or even the normal noises of the surrounding world, so she had to maintain constant vigilance. Her stress hormone levels became skewed; her health deteriorated. She couldn’t resettle elsewhere, because she had a nest full of hatchlings to tend. Yet her chicks suffered too, growing up small and scantily feathered — if they survived at all.

Scientists couldn’t ask the bluebird what she was feeling. But when they sampled the bird’s blood, as part of a study of 240 nesting sites surrounding natural gas treatment facilities in northern New Mexico, they found she showed the same physiological symptoms as a human suffering from post-traumatic stress disorder.

“Noise is causing birds to be in a situation where they’re chronically stressed . . . and that has really huge health consequences for birds and their offspring,” said Rob Guralnick, associate curator of biodiversity informatics at the Florida Museum of Natural History.

It would be a stretch to say noise hurts birds’ mental health — the animals have not been evaluated by an avian psychologist. But in a paper published Monday in the Proceedings of the National Academy of Sciences, Guralnick and his colleagues say there is a clear connection between noise pollution, abnormal levels of stress hormones, and lower survival rates. This is the first time that link has been established in a population of wild animals, they argue, and it should make us all think hard about what our ruckus is doing to the Earth.

“Habitat degradation is always conceived of as clear cutting, or, you know, changing the environment in a physical way. But this is an acoustic degradation of the environment,” Guralnick said. “We think it is a real conservation concern.”

The research was conducted at the Bureau of Land Management’s Rattlesnake Canyon Habitat Management Area, a sun-drenched expanse of sage-brush-covered mesas and steep canyons forested with juniper and pinyon pine. The site is uninhabited, but it’s dotted with natural gas wells and compression stations that emit a constant, low-frequency hum in roughly the same range as many birds’ songs. That makes it the perfect place to study the effects of human-produced noise, far from humans themselves.
A nesting box near a natural gas facility. Researchers found that birds nesting near sources of persistent noise show signs of chronic stress. (Nathan Kleist)
Clint Francis, an ecologist at California Polytechnic State University, has been studying this ecosystem for more than a decade. In previous studies, he has reported that noise can restructure entire communities — prompting birds to alter the pitch of their songs, shifting demographics toward more noise-tolerant species, even changing the distribution of plants based on what birds remain. He also found that some species fared better when they nested near noise sources, because the clamor drove away predators that would otherwise eat vulnerable eggs and chicks.


“But we were still concerned there might be hidden costs when you measure other aspects of reproductive success,” Francis said. “That’s why we wanted to look at stress hormones.”

Blood tests revealed that levels of corticosterone in birds closest to the gas compressors were far, far lower than normal. This initially came as a surprise to the researchers, because corticosterone is the bird equivalent of cortisol — the hormone that prompts your body to release a flood of adrenaline, bump up your blood pressure, and jolt your brain with sugar.

But then they took their results to Christopher Lowry, a stress physiologist at the University of Colorado at Boulder. To him, the results weren’t surprising at all — it’s what you would expect in a creature exposed to prolonged, persistent strain.

Humans suffering from PTSD or chronic fatigue syndrome, and lab mice that have been put through traumatic experiences, respond by muting their hypothalamic-pituitary-adrenal (HPA) axis — the cascade of chemical responses that is triggered by stress.

One response to this post.

  1. Posted by Anonymous on January 10, 2018 at 3:31 pm

    What an amazing and sad story.

    Nature and our environment are sacred and not a political volley ball.

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