Although bears maintain a calm demeanor when in the presence of unmanned aerial vehicles (UAVs), their heart rates soar and thus signal a sign of acute stress, according to a study from University of Minnesota researchers.
The university explains that UAVs have become increasingly valuable to wildlife researchers by providing a way to observe animals in their natural settings from long distances and over difficult terrain.
Until now, though, researchers thought the animals were taking these encounters in stride. For instance, American black bears rarely seem to startle or run away when a UAV comes near.
However, the university says, the new study reveals an increase in the animals’ heart rate.
“Some of the spikes in the heart rate of the bears were far beyond what we expected,” says Mark Ditmer, a post-doctoral researcher in the university’s Department of Fisheries, Wildlife and Conservation Biology. “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.”
The researchers fitted free-roaming American black bears living in northwestern Minnesota with Iridium satellite GPS collars and cardiac bio-loggers. The collars sent the researchers an email with each bear’s location every two minutes while the bio-loggers captured every heartbeat. Then, Ditmer and his colleagues programmed a UAV to fly to the bear’s most recent location.
The researchers used a 3D Robotics quadcopter to autonomously fly 20 meters (65 feet) over the animals.
In the end, the researchers were able to analyze their data very precisely to find out what hidden effects their UAV flights – which lasted only five minutes due to battery life and other logistical constraints – might have had on the bears.
In 18 UAV flights taken in the vicinity of four different bears, individuals only twice showed any major change in their behavior in response to the UAVs. However, the bio-loggers revealed consistently strong physiological responses. All of the bears in the study responded to UAV flights with elevated heart rates. Fortunately, the bears recovered very quickly, the university says.
“Without the use of the bio-logger, we would have concluded that bears only occasionally respond to UAVs,” Ditmer explains.
The researchers say it will now be important to consider the additional stress on wildlife from UAV flights when regulations and best scientific practices are developed.
“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.”
Ditmer and his colleagues are now working with captive bears to find out whether the animals can get used to overhead UAV flights over time and, if so, how long it takes. The research was funded in part by the university’s Institute on the Environment and the International Association for Bear Research and Management.
The full study can be found here.
Photo courtesy of the University of Minnesota: Mark Ditmer downloads the current GPS coordinates of a collared bear to input into a UAV mission.