Science Moab: How does noise affect bighorn sheep?

Science Moab chats with Joel Berger

Joel Berger grew up in Los Angeles, but traded surfing for desert and mountain adventures when he moved to Utah. Gradually, he found himself gravitating to wildlife science: he’s been studying bighorn sheep in North America and British Columbia for years. Science Moab chatted with him about his most recent project, which is funded by the Canyonlands Natural History Association’s Discovery Pool grant. 

Science Moab: When did you start looking into how noise affects the lives of desert bighorn? 

Berger: I was talking to a number of folks in and around Moab about the noise ordinances and increasing levels of aerial activity here, like helicopters or sightseeing planes. People said, Joel, since you’re focusing on bighorns already in recreation, is there a way you could look at the sensitivity of bighorns to sound? So this research came about through the concerns of locals; of ranchers, recreationists, the business community, and government agencies.  

Science Moab: Not a lot is known about how noise affects sheep, especially recreational noise in southeastern Utah. How did you go about designing this study?

Berger: So the major thing that we want to know is how bighorn females respond to noise. Most of the recreation in southeastern Utah occurs during the spring and late spring. This is exactly when females are in their last trimester of pregnancy. We know that it can be really stressful in late pregnancy, and that’s when animals need access to highly proteinaceous grasses. Wild bighorns in Utah are not in experimental settings, we don’t bring them into a captive facility to play sounds. So we need to be creative. We’re exposing females in groups to three kinds of sounds: the sounds of motorcycles, sounds of people talking, then we use a familiar sound, like a raven.   

Science Moab: You’ve only had one real season collecting data. But what, if anything, can you tell us about what the data is showing so far? 

Berger: It depends on group size, and it depends on the habitat. What we’ve been finding so far, is that if the sheep are surprised, they respond pretty strongly. We know many of the trails, whether they’re hiking trails, mountain biking trails, motorcycle or OHV trails, some have a lot of turns and switchbacks in them. If the sheep can’t hear things coming, they get surprised real quickly. And they’re likely not only to bolt, but to go far. We saw pregnant sheep move three or four miles at a time. 

So that’s an important one: we know that they’re more vulnerable when they get surprised. Sometimes they hear sounds coming, and if they have a chance to prepare, and then they tend not to bolt, they just move off. 

Science Moab: So if your findings are that recreational sounds are adding more stress to the bighorns, especially the females, what do you hope could be some of the outcomes of this study?

Berger: My hope would be that we could bring together different stakeholders, hold workshops across different parts of Utah, and get a much better feel for what the public is thinking and try to come to some sort of an agreement on where the best places are to put effort. How do we educate the public and make this work best for everybody?

​​Science Moab is a nonprofit dedicated to engaging community members and visitors with the science happening in Southeast Utah and the Colorado Plateau. To learn more and listen to the rest of this interview, visit www.sciencemoab.org/radio.