The call of the wild is getting harder to hear. Peaceful natural sounds—bird songs, rushing rivers, rustling grass—are being drowned out by noise from people in many of America's protected parks and wilderness areas, a new study in the journal Science finds. Scientists measured sound levels in 492 places, from city parks to remote federal wilderness, the AP reports. They calculated that in nearly two-thirds of the Lower 48's parks, the noise can at times be twice the natural background level because of airplanes, cars, logging, mining, and oil and gas drilling. That increase can harm wildlife, making it harder for them to find food or mates, and make it more difficult for people to hear those natural sounds, the researchers say.
In about one in five public lands, there has been a tenfold increase in noise pollution, per the study. Except for city parks, though, the researchers—including a National Park Service unit—didn't find sound levels people would consider unusually loud (think changing from the quiet of a rural area to a still pretty-silent library)—but that difference masks crucial sounds, especially to birds seeking mates and animals trying to hunt. Colorado State University biologist George Wittemyer, a co-author of the research, says people hear only half the sounds that they would in natural silence. And it makes a difference for peace of mind. "Being able to hear the birds, the waterfalls ... those are really valuable ... [to] help in [humans'] rejuvenation and their self-reflection," he adds. Study lead author Rachel Buxton notes there are still places to escape to, such as Colorado's Great Sand Dunes National Park. (Read more discoveries stories.)