Drones Cause a Stress Response in Bears

American black bears react the same way as humans to unidentified objects flying overhead: They find it disturbing. With the increased use of unmanned aerial vehicles (UAV), or drones, by wildlife biologists to observe animals that include endangered species, researchers recently studied bears' reactions to drones in northwestern Minnesota and reported their findings in the journal Current Biology. 

Ultimately, the scientists found that although the bears appeared calm when drones flew over, their heart rates raced, showing acute stress. "Some of the spikes in the heart rate of the bears were far beyond what we expected," said 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."

In the study, the research team observed free-roaming American black bears using Iridium satellite GPS collars and heart rate monitors, monitoring the bears' location and movement. In September and October 2014, they conducted 18 flights of a small quadcopter above or near the bears. All of the bears in the study reacted to the flights with elevated heart rates--but recovered quickly, fortunately. 

The researchers have concluded that caution is necessary, going forward: "UAVs hold tremendous potential for scientific research and as tools for conservation," Ditmer said in a release. "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."

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