Quirks & Quarks·Bob McDonald's blog

Let nature do the talking

A study using nearly 47,000 hours of audio recording reveals national parks can be noisy places

A study using nearly 47,000 hours of audio recording reveals national parks can be noisy places

Park rangers meet in front of Yosemite Falls in Yosemite National Park, California. Nearly 47,000 hours of audio recordings in U.S. national parks reveals how noisy national parks can be. (David Calvert/Getty Images)

The peace and quiet of national parks are being invaded by the sounds of humanity. A two decade-long project that recorded sounds in parks across the U.S., found that noise from human activity causes a 10-fold or greater increase in natural background sound levels, which can affect animal behaviour.

The project, involving the U.S. National Park Service and Colorado State University, recorded 46,789 hours of sounds from microphones placed in 251 sites in 66 parks from across the continental U.S. The recordings picked up everything from wind, rain, lightning and animal sounds and found that noise from people and machines was picked up in 37 per cent of recordings. While the noise is significant, it is also quite localized, representing less than two per cent of the total National Park Service lands.

A moose is shown running in front of a car as it crosses the road in Gros Morne National Park in N.L. Vehicles are one of the noisiest culprits in national parks. (Jonathan Hayward / The Canadian Press)

Sources of noise in National Parks

The biggest culprits were planes, trains and automobiles. But human voices were also a component. People are noisy creatures when walking in the woods, chatting and laughing along the trails. Part of the human cacophony also included park rangers giving guided talks. Together, these unnatural noises in the woods can affect wildlife who rely on sound to call to each other and find mates during breeding season, or listen for the sounds of approaching predators.

The subtle sounds of wilderness are often forgotten as we babble with each other in the forest. But if you just stop and listen for a minute or two, a whole other world opens up.

Point Pelee National Park in Ontario is a popular destination for bird watchers. (Point Pelee National Park / Parks Canada)

Serenity in natural soundscapes

I had an opportunity to appreciate the quiet of the woods during a bird count at Point Pelee, a bird sanctuary on the shores of Lake Erie. With binoculars around my neck I joined a group of expert bird watchers on a walk through the forest. At first, I was chatting and telling jokes along the way, but no one else was really laughing or engaging in conversation.  

Tough crowd.

Then someone said, "Warbler." Everyone stopped and listened. A faint chirp came from above. The group scanned the trees looking for the source of the sound, then one of them aimed a spotting scope at a nearby bush, and there was the colourful bird among the branches.

This is a photo of a Canada Warbler. One of the best places to see warblers is in Point Pelee National Park, which is considered to be "the warbler capital of Canada." (Jeff Nadler)

It suddenly struck me that the reason everyone was so quiet is because they were listening for bird calls and ready to identify the species. When bird watchers walk in the woods, they are quiet, then they stop, listen and look. They let nature do the calling. With that realization, and walking in silence from that point on, the forest experience changed entirely. A chorus of songs from a variety of bird species filled the air. It was an enlightening experience and forever changed the way I take hikes in the wilderness. (On the other hand, if you are in bear country, a bear bell is a good idea, just to let the bears know you are there.) 

Audio equivalent of dark sky preserves 

So while parks can mitigate vehicle noise by restricting speed limits and incorporating shuttle busses, or use quiet pavement materials on roads to dampen tire noise, or even work with aviation authorities to shift air corridors away from parks, they can also introduce quiet zones. These areas of silence would not only make it easier for wildlife, they would enhance the visitor experience tremendously by introducing people to the soundscapes of nature.

Many parks are designated dark sky preserves, restricting lighting so the stars of the night sky can be seen. Quiet zones can do the same for sound.

About the Author

Bob McDonald is the host of CBC Radio's award-winning weekly science program, Quirks & Quarks. He is also a science commentator for CBC News Network and CBC-TV's The National. He has received 12 honorary degrees and is an Officer of the Order of Canada.