Kurt Fristrup and Karen Trevino. Photo by Damon Joyce.
It is getting louder all the time. It used to be easier to escape the din, and national parks and our other public lands were among the spots you could find peace and quiet. Most of these places remain the best prospects for basking in natural sounds, but the decibel level is on the rise.
In 1975, as concern grew about the proliferation of low-altitude air tours over the Grand Canyon, Congress passed the Grand Canyon National Park Enlargement Act of 1975, which directed the Secretary of Interior to take action to prevent any aircraft or helicopter activity “likely to cause a significant adverse effect on the natural quiet and experience of the park.” Subsequent laws and regulations led to enhanced efforts by federal agencies to protect natural sound.
Karen Trevino manages the Park Service’s natural sounds and night skies programs and also sits on the National Wilderness Leadership Council for NPS. Based in Fort Collins, Colo., she works with Park Service acoustics experts like Kurt Fristrup. Wilderness magazine spoke with Trevino and Fristrup to learn more about what wildlife and visitors are hearing these days in the national parks.
Q: What are some of the natural sounds that you can hear at our parks?
A: The call of the coyote, the howling of a wolf, people laughing, bird songs, wind, people snoring, waterfalls, and rustling leaves are just a few of those sounds. The list is long and varied.
Q: And what are the sounds that are making it harder to hear natural sounds?
A: Transportation sources like planes, buses, cars, motorized recreation vehicles such as ATVs OHV's and Jet Skis, park operations, and activities on adjacent lands such as construction, energy development and mineral extraction account for most of the noise.
Q: Although the impact on humans is important, all this noise probably has a more serious effect on wildlife. True?
A: Quite possibly. Wildlife biologists who initially thought that noise was not a cause for much concern are finding in their research that this is a serious threat. Most animals use sound to chart activities in their vicinity. You can break these sounds into two categories: 1) sudden noise that startles wildlife and forces movement to an area that probably does not meet their needs as well, and 2) noise that has a masking effect so that they have trouble hearing sounds that are vital to them.
Q: Can you give us an example?
A: Yes. Great grey owls are capable of hearing mice under a foot of snow and then diving down to catch them. When the sounds of those mice are masked, the owls’ ability to find enough food is compromised. When animals flee sounds that frighten them, they waste energy and are distracted from activities that are central to their survival such as eating and procreating. There can be serious reductions in reproduction. Research is also showing that some birds are changing their mating songs because of noise.
Q: What are you hearing from visitors?
A: A lot. For example, we’re receiving more and more complaints about motorcycle noise from “after-market” exhaust systems. There are a number of them, and they feature names like “Screaming Eagle.” As such names imply, these devices are installed with the express purpose of making the vehicle louder. One irony is that most government regulation of noise focuses on urban areas, in part because of a sense that there’s less of a problem in rural settings. The result is that one back-country vehicle is permitted to be as loud as 60 or 70 passenger vehicles.
Q: And how do things look up in the sky, with aircraft?
A: The Park Service has less control there. The Federal Aviation Administration, which has most of the jurisdiction, has forecast that over the next ten years the number of national park air tours will grow from 180,000 to nearly two million. That’s a ten-fold increase. A large percentage of the current flights are at the Grand Canyon, Lake Mead, and the parks in Hawaii. They are also a major concern at Mount Rushmore because the tours occur in such a concentrated area.
Q: How is noise affecting people who use wilderness areas?
A: For most back-country wilderness visitors, natural sounds are an important element in the solitude that they seek and expect these areas to provide. The Park Service’s National Wilderness Council is trying to address this.
Q: Does the Park Service compile information on natural sounds?
A: We are building an inventory and have recorded these sounds in more than
55 parks. This provides a baseline so that we can measure change. Among the most intriguing sounds we’ve taped are a protest call from a bear cub, exchanges between a great horned owl juvenile and adult, and a chorus of elk bugling.
Q: What else have you learned?
A: There are surveys showing that 90 percent of respondents believe that natural sounds are an important reason for creating a park in the first place and a central part of the national park experience. Also, noise has been shown to affect other sensory perceptions, changing a person’s overall park experience. We have started looking into how noise can compromise your sleep in a national park. It might be a plus to wake up when a wolf howls but not when you hear a Jet Ski or helicopter.
photos: Kurt Fristrup and Karen Trevino. Photo by Damon Joyce.
Helicopter over the Grand Canyon.