Drones make black bears' heart rates rocket by up to 400%, raising questions about the role of these devices in studying the natural world.
Drones, or unmanned aerial vechicles (UAVs), are often used in conservation to track species. This research questions whether scientists should reconsider their methods.
In this study, American black bears in northwest Minnesota were collared and tagged with GPS trackers and heart rate monitors as part of a study at the University of Minnesota, St Paul.
Writing in Current Biology, the team measured the bears' heart rate and behaviour when a drone hovered and manoeuvred over the bear’s location.
As the drone approached, the bears’ heart rates spiked. In the most severe case, heart rates increased from 41 to 162 beats per minute, suggesting that the bears where stressed by the UAV. Interestingly, the bears showed no behavioural changes.
“Had we only measured their movement or watched them...we would have incorrectly concluded that bears do not respond to UAV flights," Dr Mark Ditmer from the University of Minnesota explained.
As drone exposure increases, the bear’s physiological response could result in adverse health impacts. If the bears are unable to habituate to drone use they may develop chronic stress, which is associated with a number of health problems including reduced immunity, increased susceptibility to infection and giving birth to smaller young.
Drones are very popular in ecological research. They enable easy access to rough and difficult terrain and provide a cost effective way of collecting data and, as the team point out, "if you put a camera on a drone and fly it around an endangered species it might deter poachers.”
Although drones have tremendous potential for research and conservation, Ditmer warns that perhaps caution should be exercised in the future.
“Maybe we don’t want to be flying them too close to individuals that are maybe endangered.”