Drones Stress Out Bears, Study Says

Blacks bears get stressed out by the presence of drones, a study suggests. Jim Urquhart / REUTERS

Drones can be useful for surveying wildlife and searching for poachers. But might they scare the animals? A new study in Current Biology shows that unmanned aerial vehicles (UAVs) raised the heart rate of black bears in the nearby vicinity, suggesting the drones stress out the animals.

In the study, scientists from the University of Minnesota fitted four wild black bears with heart rate monitors, and detected what happened when a quadcopter was flown within about 60 feet of the animals for five minutes at a time. These types of short-lived but close encounters are becoming more common as drones get more widely available, and UAVs are regularly flown close to rhinos in South Africa and many other animals for ecotourism purposes. Oil and gas companies have also been known to fly UAVs over various Arctic species to "meet environmental and safety rules before drilling on the seafloor," according to the Federal Aviation Administration .

There are basically no regulations on how close drones can come to animals, and it likely is happening more and more often, the scientists write.

"Some of the spikes in the heart rate of the bears were far beyond what we expected," says Mark Ditmer of the University of Minnesota, St. Paul, in a statement. "We had one bear increase her heart rate by approximately 400 percent—from 41 beats per minute to 162 beats per minute. Keep in mind this was the strongest response we saw, but it was shocking nonetheless."

That surprised the scientists since the bears didn't appear to change their behavior in response to the drones. So, while they looked unphased, they were indeed spooked. More research is needed to further understand the unintended effects drones might have on wildlife, the scientists concluded.

The figure in (A) shows the movement rates, in meters per hours, of a female black bear before, during and after a drone flies nearby, which is outlined in gray. Though she doesn't move more, figure (B) shows that her heart rate spiked during the time period when the drone was nearby, showing that the UAV stressed her out. Ditmer et al / Current Biology