Puma
Like great white sharks and grizzly bears, mountain lions are one of the most fearsome wild animals for many Americans.

But new research shows that the lions may be more afraid of us than we are of them.

Scientists at UC Santa Cruz placed audio and video equipment in the Santa Cruz Mountains near areas where lions had killed deer and other animals. When a lion came to feed, a motion-activated device broadcast the sounds of people talking and Pacific tree frogs croaking, in addition to turning on a tiny hidden video camera.

In 29 experiments with 17 lions from December 2015 to June 2016, the lions ran away in 83 percent of cases as soon as they heard human voices — and only once when they heard the frog sounds.

"People allude to this idea all the time — that mountain lions are more afraid of us than we are of them. But science has never shown that before," said Chris Wilmers, an associate professor of environmental studies at UC Santa Cruz who worked on the study. "When people go out hiking, some have a fear that mountain lions are going to attack them. But it turns out that mountain lions are quite afraid of people."

The study was published Tuesday in the Proceedings of the Royal Society B, a scientific journal published by the Royal Society of London.

It is part of broader research that UC Santa Cruz's Puma Project has conducted since 2008 in which the biologists track lions, shoot them with tranquilizer darts, fit them with GPS collars and track their behavior with computers.

All 17 of the lions, also called pumas and cougars, studied in the sound experiment were fitted with GPS collars. They come into contact regularly with communities in the Skyline area, the Lexington Basin near Los Gatos and near Big Basin State Park.

"They get quite close. We've had mountain lions kill deer within a few feet of people's homes," said Justine Smith, lead author of the study, and now a postdoctoral researcher at UC Berkeley. "People send us videos of pumas walking through their yards, standing on their cars. But we almost never hear of direct physical encounters.

"For some people it's creepy," Smith said. "For others, it's reassuring to know they have been around the whole time but they avoid us. They keep out of the way for the most part."

The recordings that were played in the lion experiment were snippets of shows of TV and talk radio personalities, including liberal Rachel Maddow and conservative Rush Limbaugh.

"We used them because they were high-quality recordings," Smith said. "But the pumas showed no partisanship. They all ran away from everyone."

The research could not only help reassure people who may be afraid of mountain lions, but also be used to help develop tools to keep them away from rural homes and farms, said Lynn Cullens, executive director of the Mountain Lion Foundation, a nonprofit in Sacramento.

"It's rational to be afraid of an animal that could do damage to you," she said. "But it's important to put that in perspective. If you normally take a hike in the woods with your friend or your spouse in the evening, the risk of being attacked by a mountain lion is so low that the risk is greater to your health if you don't take your walk."

Mountain lions are found across the American West. Adult males can reach up to 9 feet long and weigh 200 pounds. They mostly eat deer, but also will eat wild boar, raccoons, opossums and other animals, including livestock and pets at times.

California placed a bounty on mountain lions from 1907 to 1963, paying anyone who would kill one. Sport-hunting of lions followed, but was banned in 1971 under a law signed by then Gov. Ronald Reagan. After that law expired in 1986, California voters banned sport hunting of cougars mountain lions in 1990 with the passage of Proposition 117.

Today it's estimated that between 4,000 and 6,000 mountain lions live in the state.

Attacks on people are extremely rare. There have been 14 mountain lion attacks on humans since 1986 in California, three of them fatal. Far more people die from dog attacks, hitting deer with cars and other animal encounters.

The most recent fatality was Mark Reynolds, 35, who was killed in 2004 at Whiting Ranch Wilderness Park in southern Orange County while he was crouching to fix the chain on his mountain bike.

California state law allows for mountain lions that threaten people, or which attack pets or livestock, to be killed by holders of so-called depredation permits.

In 2015, the most recent year for which data is available, 101 mountain lions were legally killed statewide, including five in Sonoma County, three in San Mateo County, two in Monterey County, and one in Alameda and Napa counties. None were killed in Santa Cruz, Santa Clara, Contra Costa, Marin, Solano and San Benito counties. The county where the most were killed was El Dorado, in the Sierra Nevada.

The UC Santa Cruz research showed that lions exposed to a human voice were slower to return to their dead deer to feed on later, and spent half as much time with the carcass as lions who did not hear human voices.

To make up for the lack of food, they have to kill more deer than if they had not encountered humans, which Smith said demonstrates that as more people move into mountain lion habitat they will impact the food chain even if they are never seen by their biggest predators.