Federal animal damage control specialists performing night watch over an Oregon cattle herd that had experienced repeated wolf attacks waited with thermal imaging for the wolves to return under the cover of darkness. When the cattle appeared restless, or a wolf emerged from the nearby treeline, the specialists then set out a high-tech drone to find and chase the wolves away from the cattle. It was a successful experiment that agency officials will continue to investigate and refine, adding another tool to the toolbox of non-lethal deterrence measures for predators.

When state and federal officials in Oregon requested USDA Wildlife Services join them in night watch activities to prevent wolf depredation on a cattle herd in the Klamath Basin, Wildlife Services agreed to assist.

Wolves in this portion of western Oregon remain under federal protection. Between July 12 to Aug. 1, 2022, the Rogue Wolf Pack had 11 confirmed depredations on cattle, but lethal control of these wolves was not an option for wolf managers.

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Each evening, personnel would push the cattle a few hundred yards out into an open pasture and away from a fence separating it from the nearby forest. Using thermal optics, agency personnel would wait and watch for wolves to cross from the trees toward the cattle before taking action to haze the wolves away. While the effort was relatively effective, it was limited by the amount of area an individual could scan with the thermal imaging device from the ground.

To increase the effectiveness of the night watch, Wildlife Services sought and received permission from the U.S. Fish & Wildlife Service to use a drone equipped with a thermal imaging camera to monitor and haze wolves in the Klamath Basin, according to a paper recently published in the journal Global Ecology and Conservation. In publishing the paper, the researchers also provided six video clips of the drone hazing wild predators (although the video clips do not include the audio recordings).

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THE FIRST ENCOUNTER

In the first encounter with the drone, a wolf watched with interest as the drone approached, prompting the wolf to play bow in response. Instead of being afraid of the drone, the wolf interacted with it as though this was a new “toy” to play with. The drone was equipped with lights, but no speaker, and the rotor noise by itself wasn’t enough to scare the wolf.

That prompted the drone operator to attach a speaker to the drone and return to the wolf as it began to approach the nearby cattle. The wolf once again demonstrated playful behavior toward the drone, but when the pilot yelled at the wolf through the speaker, the wolf turned and ran away from the drone as it continued to haze the wolf out of the pasture.

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Throughout the course of the experiment, the drone operator used lights or sound (music, recorded gunshots, or the drone pilot’s voice) to haze wolves whenever the animals were detected approaching cattle, but found that the human voice was most effective at deterring wolves.

STOPPING AN ATTACK

The effectiveness of the drone was demonstrated in a video in which three wolves are seen actively attacking a steer. One wolf turns and runs as the drone approaches, but the other two wolves continue attacking the steer. When the drone pilot yells at the two wolves through the speaker, the wolves immediately stop their attack and run away. The steer survived the attack and only needed minor medical attention the next morning.

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Prior to the use of drones during the night watch, the pack had 11 confirmed cattle depredations in 20 days. During the next 85 days, there were two confirmed cattle depredations and 51 interactions between wolves and the drone.

The paper concludes “the addition of drones to the night watch effort using drones conducted by [Wildlife Services] in the summer of 2022 appears to have effectively reduced the number of livestock depredations.”

LIMITATIONS

The researchers noted a variety of limitations for using drones to haze wild predators. First is the drone battery life, with about 22 minutes of flight time before recharge is needed. One of the videos uploaded with the paper demonstrates the significance of this shortcoming by showing a wolf attacking a cow as the drone approaches. As the drone moves closer to the wolf to begin hazing, the drone suddenly aborts the mission to return to its home base for a recharge, an automated response to a low battery. Although the drone operator had already summoned the ground crew to help chase the wolf away, the cow had to be euthanized due to severe injuries. This was one of the two confirmed kills during the drone-assisted night watch.

The researchers note that advances in battery and drone technology should help to increase flight times, as well as the ability to change batteries without powering down the drone. Other limitations involve topography and land cover. In thick vegetation, the drone pilot may be unable to maneuver close enough to a wolf for hazing, or obstructions may pose a risk of crashing the drone (as demonstrated in one of the project’s videos). The drone must remain within the line of sight of the drone operator, which also poses limitations. Although prices are expected to decline as drone use becomes more widespread, these equipped drones range in cost from $10,000 to $20,000 each, posing an economic feasibility limitation to broad application.

FUTURE RESEARCH

Wildlife Services plans to continue investigating the effectiveness of drones as a non-lethal tool to deter predators. Wildlife Services National Wildlife Research Center Utah Field Station Leader Dustin Ringlack said that the research will expand to answer questions about the effectiveness and limitations of drone use.

In addition to exploring the amount of effort needed for drones to be effective (man hours, flight hours, spatial patterns), researchers will conduct a large trial in different canopy covers to gauge at what level canopy cover becomes limiting for a drone to detect wolf-like animals.

They will also continue to document the behavioral reactions of wolves and other wildlife to the drone, providing insights to wildlife managers, livestock producers, and the general public. Although wolves eventually habituate to most non-lethal tools, the adaptive movement of a drone may help to prevent wolves from habituating, offering promise for continued application of drones to keep livestock safe from attacking predators — a new tool in the toolbox.

The paper, “Drones as a potential hazing tool to prevent wolf depredations on livestock,” was co-authored by Dustin Ranglack, Loredana McCurdy, Paul Wolf, and Luke Miller read the paper and view the videos at https://tinyurl.com/3tf44mb4. Videos of the drone in action show the hazing of wolves, coyotes and a black bear.