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

However, a group of biologists stationed near the California-Oregon boundary does know about them and is employing the sounds of AC/DC’s “Thunderstruck,” film snippets, and live human voices to deter these top predators from cattle through an ongoing experiment.

“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 almost entirely wiped out across the U.S. West by the early 20th century. Following their reintroduction in Idaho and Yellowstone National Park during the mid-1990s, they have thrived to the extent that the Northern Rockies population is no longer considered endangered.

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

The resurgence of the wolf population has led to increased tensions with ranchers, prompting more inventive strategies to safeguard their livestock. Ranchers have resorted to using electric fencing, wolf alarms, guard dogs, patrolling on horseback, trapping and relocating wolves, and now, drones. In places where non-lethal methods have not succeeded, authorities frequently permit the culling of wolves, including recent approvals in Washington state.

In 2022, gray wolves were responsible for the deaths of approximately 800 domesticated animals across ten states, as reported by an earlier Associated Press examination of data from state and federal agencies.

Researchers from the USDA Animal and Plant Health Inspection Service crafted drone techniques to haze wolves while keeping an eye on them with thermal imaging cameras during nighttime hours, which is their peak activity period. A preliminary study published in 2022 indicated that broadcasting human voices through a speaker attached to a drone can startle them considerably.

The team has noted successful disruptions of wolf hunting activities. Dustin Ranglack, the USDA’s principal investigator on the project, grinned widely the first time he witnessed one.

“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.”