Over three years, Mr. Sarmento and his thesis adviser, Joel Berger, a scientist at the Wildlife Conservation Society and a professor at Colorado State University, closely observed mountain goats near and away from tourist-heavy areas in Glacier National Park, noting where the goats got their minerals and how cautiously they behaved. One of these sites, Logan Pass, receives about 3,500 visitors a day. At peak hours on a popular hiking trail there, a goat might encounter 400 people an hour.
To test how mountain goats reacted to predators, Mr. Sarmento dressed up as a bear and presented himself to goats at both tourist and backcountry sites, noting their responses (yes, this is a credible technique used in ecology research). He also took advantage of a nearby wildfire that led the park to close Logan Pass for a week in 2015, to see what goats did when there were no tourists.
The scientists determined that while predators and pee both were at play, predators seemed to be driving goats’ behavior. Mountain goats that stuck around humans were generally not as vigilant as their backcountry counterparts. When presented with the bear mimic, backcountry goats fled, on average, 600 feet farther than those near people.
During the wildfire closing, goats that usually hung around Logan Pass returned to the cliffs. There was still plenty of urine around — goats can lick the same patch for up to 10 days — but the researchers’ predator cameras picked up more bears at Logan Pass that week than they had over two years, suggesting the promise of salt was not worth the risk. Once people returned, the goats did too.
The researchers also noted that goats habituated to people stopped their annual migration to a natural mineral lick. “If mother goats aren’t passing that behavior onto their young, they might lose a migration that has accrued for thousands of years,” said Mr. Sarmento, who now works for Montana Fish, Wildlife and Parks.
There may also be more instances of aggression if mountain goats get more comfortable around people, Mr. Sarmento added, noting that a mountain goat killed a hiker at Olympic National Park in Washington State in 2010.
Studies like this show how national parks must grapple with the conflicting mandates of preserving nature and providing recreation for visitors, said Laura Prugh, an assistant professor of wildlife at the University of Washington who was not involved in the study.
One thing visitors can do is minimize their interactions with wildlife in these spaces, she said. “It might make for nice photographs,” she said, “but it can really be detrimental in the long term.”