National Wildlife Refuge System
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Mapping Kenai's Soundscape

Tim Mullet, Kenai Refuge biological science technician and doctoral student at the University of Alaska, takes sound-level measurements on the refuge in Alaska.
Tim Mullet, Kenai Refuge biological science technician and doctoral student at the University of Alaska, takes sound-level measurements on the refuge in Alaska.
Credit: Matt Bowser, USFWS

Why does Tim Mullet plan to collect moose poop for a two-year study of noise levels on Kenai National Wildlife Refuge in Alaska.  Because bagging moose pellets is safer and easier than taking blood samples from wild horned animals weighing half a ton and up.

Mullet, a biological technician at Kenai Refuge and a PhD candidate at the University of Alaska Fairbanks, will test the moose poop for levels of glucocorticoids — hormones that are indicators of animal stress.¬† Chronic high levels of these hormones can lower wildlife densities and displace animals from preferred habitat. Mullet hopes to find out whether exposure to human-made noise causes such stress.

One source of human-made noise is snowmobiles. In Alaska, snowmobile use is permitted, especially for hunting and fishing, even in wilderness areas. The 1964 Wilderness Act defines these as pristine places that are subject to minimal human disturbance and offer "outstanding opportunities for solitude." Some 1.3 million acres of Kenai Refuge's approximately 2 million acres is congressionally designated wilderness.

But noise from human activity is penetrating deeper into wilderness areas, and growing recreational use of snowmobiles has sparked some visitor complaints, says John Morton, supervisory wildlife biologist at Kenai Refuge.  The area also absorbs noise from Sterling Highway, which passes through the refuge.

"At this point, I've got an idea 30 to 40 percent of Kenai's wilderness could be affected by human–made noise," says Mullet. His study will map a "soundscape" of the refuge, based on sound-level readings and recordings and predictive modeling. Sound is measured in decibels (dB), with conversation usually measuring about 60 dB and a jet take-off about 120 dB, loud enough to cause permanent hearing loss.

Readings previously taken on the refuge include 95 dB for low-flying aircraft and 120 dB on or near Sterling Highway.

Sound samplings are set to begin in the next few months. Says Mullet, "As far as I know, nobody has attempted to model sound in the landscape. We could encounter some big surprises there."

For more information about Kenai National Wildlife Refuge, visit http://kenai.fws.gov/ or call 907-262-7021.

To read Tim Mullet's "Stop to Hear the Decibels," visit http://kenai.fws.gov/overview/notebook/2010/july/16july2010.htm.

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