The buzzing racket of quadcopters and drones may be stressing wildlife, a new study shows. Drones have long ceased to be the provision of the military, and are now extensively been used for civilian purposes. Amazon, for instance, wants one day to deliver all its goods with unmanned aerial vehicles. In research, drones have proven to be particularly useful in observing wildlife. But these aren’t as unobtrusive as some might believe and future research should take into account that flying drones overhead should be done carefully so as to not disturb the wildlife.

In this remarkable capture from above, we see a grizzly bear guarding a massive bison carcass. The photograph was taken by Doug Smith at Yellowstone National Park. Smith, who is the leader of Yellowstone’s Wolf Project, suspects that the bear happened upon the recently deceased bison and has now assumed ownership of the meal against other would be diners such as wolves [Source: BettPratt.com].

Mark Ditmer, a postdoctoral researcher in the University of Minnesota’s Department of Fisheries, Wildlife and Conservation Biology, was still keen on investigating though. Since he couldn’t ask the bears how they felt about the drones peering into their lives, Ditmer and colleagues strapped four bears in northwestern Minnesota with a GPS collar and cardiac biologgers. The latter monitors and records heart rate.

The researchers flew an UAV above each bear for one to nine times, then looked at the heart rate data. They found that each time the UAV was flying above them, the bears’ heart rate spiked immediately, despite their seemingly calm composure. This reaction suggests the bears are stressed.

“We had one bear increase its 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,” the researcher explained.

Bears living in the area are quite used to humans and anthropomorphic environments, which is why they didn’t maybe run away or immediately panicked. In the case of wildlife unaccustomed to humans, the response to drones might be a lot more dramatic. Mating rituals could be disturbed, and some animals might injure themselves.

“Without the use of the biologger, we would have concluded that bears only occasionally respond to UAVs,” Ditmer says.

That’s not to say that UAVs shouldn’t be used anymore to track animals, either for research or tourism. They’re definitely very useful. Rather, these findings might serve to guide a set of best practices when performing scientific research using drones.

“UAVs hold tremendous potential for scientific research and as tools for conservation,” Ditmer says. “However, until we know which species are tolerant of UAVs, at what distance animals react to the presence of UAVs, and whether or not individuals can habituate to their presence, we need to exercise caution when using them around wildlife.”