Apparently, bears aren't always as brave as they may seem.

When scientists watched American black bears as they flew drones nearby, the bears didn't seem bothered. However, when they strapped heart monitoring devices and GPS devices on them, the researchers saw dramatic heart rate spikes when drones — also known as unmanned aerial vehicles, or UAVs — flew by, they report in the journal Current Biology.

"Without the use of the biologger, we would have concluded that bears only occasionally respond to UAVs," lead study author Mark Ditmer of the University of Minnesota, St. Paul stated.

Yet, every bear in this study responded to the drones flying by with elevated heart rates, a sign of distress. All of the bears recovered from the incident quickly, however.

In the most extreme case, a bear's heart rate increased by about 400 percent. This was the most extreme case out of the 18 drone flights that the scientists conducted near the four bears studied, but the intensity of this reaction shows that it is possible for drones to cause animals such as bears significant distress.

"UAVs hold tremendous potential for scientific research and as tools for conservation," Ditmer said. "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."

Flying drones is not thoroughly regulated in many countries, but studies such as this one show why it is important to consider how wildlife will react to new technologies in their habitats. Perhaps the bears will get used to the drones — the researchers are currently exploring that possibility in studies with captive bears.

Photo: Neal Herbert | Flickr

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