Do Drones Create Undue Stress in the Animals They Track?

Drone Vs. Wild

Unmanned aerial vehicles (or UAVS, better known as drones) have complex interactions with the animals they monitor. Though scientists use drones to protect animals from poachers and obtain data on threatened species, evidence suggests these flying devices take an unseen toll on the creatures they track. YouTube even boasts a multitude of videos that show chimps, eagles, lions, and rams viciously attacking UAVs. So what’s going on when drone meets beast?

In the first study of its kind, scientists measured Minnesota black bears’ physiological responses to UAVs, which flew overhead 17 times. Data from sensors previously implanted in the bears revealed that in nearly all trials the animals’ heart rates significantly increased, though few behavioral reactions were noted. In the most extreme case, sensors recorded a 400% spike in one bear’s heart rate, from 39 to 162 beats per minute. University of Minnesota study leader Mark Ditmer found the results somewhat surprising, as bears in this region commonly hear loud noises from farm equipment and nearby traffic. “We thought they’d seen everything,” he said. Still, “Drones have different sounds and different capabilities. They can fly under the forest canopy, they can get very close, and even follow an individual.”


Photo: Andy Cush

David Wilkie, the Wildlife Conservation Society’s director of Conservation Support, hesitated to read too much into the findings without further research on drone-wildlife interactions, noting: “Heart rate is really an indication of arousal, a natural reaction. All animals get aroused when there’s an unfamiliar sound. It’s about vigilance, not necessarily stress.” He called for a study to measure the amount of stress hormone cortisol found in animals’ feces after UAV flight trials. Ditmer conceded that, though wild species may habituate to UAVs just as they have to highways and other manmade noises, the potentially chronic stress from constant close-up drones could have unknown consequences, even impacting bears’ success in reproducing and finding food, as well as weakening their immune systems. “If you have an endangered species or animals sensitive to human interference, we could push them beyond a threshold,” he said.

More Good Than Harm?

The key may be to test individual species’ reactions to UAVs before implementing long-term drone surveillance on them, ensuring the benefits (e.g. protecting them from poachers and obtaining insightful data) to that group always outweigh any stress inflicted. In science journal Current Biology, Australian researchers Jarrod Hodgson and Lian Pin Koh agree that “It is likely that animal responses vary depending on a variety of factors, including the species, environmental and historical context, and the type of UAV and its method of operation.” The duo outline some best practice guidelines they hope will both public and private sectors will implement to minimize stressful drone-animal interactions. For instance, Hodgson and Koh recommend that researchers choose drone models that are unobtrusive and even camouflaged, that they consider obtaining data via satellite images or manned aircraft before deploying drones, and that any negative animal responses should be shared in published studies. With these suggestions, they seek  to define drones as “a powerful, low-impact ecological survey tool” that can harvest key data on threatened populations within acting in ways that could threaten them further.


Photo: Mike Tuziw, Alamy

Clearly-defined legislation can serve to insulate wild animals from drone hobbyists, who may have no qualms about flying drones right up to wildlife for the sake of a good photo. Currently, Canadian law bans all drones within 150 meters of wild animals, while the US National Park Service prohibits drones from flying over protected land so that animal inhabitants will remain undisturbed. Wilkie noted that, after lawmakers and researchers lay out what constitutes appropriate drone behavior around wild animals, UAVS will  have “enormous potential that we’ve barely begun to tap,” and Hodgson and Koh too are optimistic. “In our experience, the vast majority of UAV users, both biologists and hobbyists, do not want to disturb wildlife and will often seek advice from experts,” Hodgson said. “By promoting an awareness of the potential for UAVs to impact wildlife, we hope that users will be more conscious of the potential impacts and utilize the code to ensure their UAV operations are responsible.” If their consequences on animal physiology are properly researched and shared amongst the scientific community, who knows the vitally important data that drones could secure on threatened wildlife species, even possibly helping them escape extinction?

-Shannon Cuthbert


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