For millennia humans have tried to scare wolves away from their livestock. Most of them didn’t have drones.

However, a group of biologists working near the California-Oregon border do, and they are employing them to play AC/DC’s “Thunderstruck,” movie excerpts, and recordings of human voices to deter these top predators from approaching cattle in an experimental study.

“I am not putting up with this anymore!” actor Scarlett Johansson yells in one clip, from the 2019 film “ Marriage Story.”

“With what? I can’t talk to people?” co-star Adam Driver shouts back.

In the early 20th century, gray wolves were nearly wiped out across the U.S. West. Their reintroduction to Idaho and Yellowstone National Park in the 1990s has led to such a population boom that they have been removed from the endangered species list in the Northern Rockies.

There are now hundreds of wolves in Washington and Oregon, dozens more in northern California, and thousands roaming near the Great Lakes.

This resurgence has led to more clashes with ranchers, prompting them to devise novel methods for safeguarding livestock. Ranchers now use electrified fences, wolf alarms, protective dogs, patrolling on horseback, trapping for relocation, and even drones. In regions where nonlethal measures have proved unsuccessful, authorities often authorize the culling of wolves, as occurred recently in Washington state.

According to a previous review by the Associated Press, gray wolves were responsible for killing around 800 farm animals across 10 states in 2022, based on information from state and federal agencies.

The USDA Animal and Plant Health Inspection Service scientists have developed drone techniques for deterring wolves, using thermal imaging cameras at night, when wolves are most active. A preliminary study published in 2022 showed that broadcasting human voices through speakers attached to drones can effectively scare them off.

The researchers recorded successful disruptions of wolf hunts. Dustin Ranglack, the project’s leading researcher at the USDA, grinned widely when witnessing one of these breakthroughs for the first time.

“If we could reduce those negative impacts of wolves, that is going to be more likely to lead to a situation where we have coexistence,” Ranglack said.

The preloaded clips include recordings of music, gunshots, fireworks and voices. A drone pilot starts by playing three clips chosen at random, such as the “Marriage Story” scene or “Thunderstruck,” with its screams and hair-raising electric guitar licks.

If those don’t work, the operator can improvise by yelling through a microphone or playing a different clip that’s not among the randomized presets. One favorite is the heavy metal band Five Finger Death Punch ‘s cover of “Blue on Black,” which might blast the lyric “You turned and you ran” as the wolves flee.

USDA drone pilots have continued cattle protection patrols this summer while researching wolf responses at ranches with high conflict levels along the Oregon-California border. Patrols extended south to the Sierra Valley in August for the first time, according to the California Department of Fish and Wildlife.

It’s unclear whether the wolves might become accustomed to the drones. Herders and wolf hunters in Europe have long deterred them with long lines hung with flapping cloth, but the wolves can eventually learn that the flags are not a threat.

Environmental advocates are optimistic about drones, though, because they allow for scaring wolves in different ways, in different places.

“Wolves are frightened of novel things,” said Amaroq Weiss, a wolf advocate with the Center for Biological Diversity. “I know that in the human imagination, people think of wolves as big, scary critters that are scared of nothing.”

There are also drawbacks to the technology. A drone with night vision and a loudspeaker costs around $20,000, requires professional training and doesn’t work well in wooded areas, making it impractical for many ranchers.

Ranchers in Northern California who have hosted USDA drone patrols agree that they have reduced livestock deaths so far.

“I’m very appreciative of what they did. But I don’t think it’s a long-term solution,” said Mary Rickert, the owner of a cattle ranch north of Mount Shasta. “What I’m afraid of is that after some period of time, that all of a sudden they go, ‘Wow, this isn’t going to hurt me. It just makes a lot of noise.’”

Ranchers are compensated if they can prove that a wolf killed their livestock. But there are uncompensated costs of having stressed-out cows, such as lower birth rates and tougher meat.

Rickert said if the drones don’t work over the long term, she might have to close the business, which she’s been involved in since at least the 1980s. She wants permission to shoot wolves if they’re attacking her animals or if they come onto her property after a certain number of attacks.

If the technology proves effective and costs come down, someday ranchers might merely have to ask the wolves to go away.

Oregon-based Paul Wolf — yes, Wolf — is the USDA’s southwest district supervisor and the main Five Finger Death Punch fan among the drone pilots. He recalled an early encounter during which a wolf at first merely seemed curious at the sight of a drone, until the pilot talked to it through the speaker.

“He said, ‘Hey wolf — get out of here,’” Wolf said. “The wolf immediately lets go of the cattle and runs away.”