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

However, a group of biologists operating near the California-Oregon border is employing them to project AC/DC’s “Thunderstruck,” snippets from movies, and live human voices at the apex predators, aiming to deter them from cattle in an ongoing 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.

Gray wolves were nearly driven to extinction in the U.S. West by the mid-20th century. Following their reintroduction in Idaho and Yellowstone National Park during the mid-1990s, they have multiplied to a point where the Northern Rockies population is no longer on the endangered species list.

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

The resurging population has led to increasing conflict with ranchers, prompting more inventive methods from ranchers to protect livestock. Techniques include electrified fencing, wolf alarms, guard dogs, horseback patrols, capturing and relocating, and now, drones. In areas where nonlethal methods have been ineffective, authorities often sanction eliminating wolves, as seen recently in Washington state.

In 2022, gray wolves killed roughly 800 domesticated animals across ten states, according to a past Associated Press review of state and federal data.

Researchers with the USDA Animal and Plant Health Inspection Service developed methods for deterring wolves using drones while observing them with thermal imaging cameras at night, when wolves are most active. A preliminary study released in 2022 showed that incorporating human voices via a loudspeaker attached to a drone can startle them.

The researchers recorded successful disruptions of wolf hunts. When USDA’s lead researcher on the project, Dustin Ranglack, witnessed one such disruption for the first time, his joy was evident with a smile from ear to ear.

“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.”