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Javier Lenzi and co-workers at the Department of Biology, University of North Dakota, evaluated the behavioural response of feral horses in the Theodore Roosevelt National Park in North Dakota, to a fixed wing drone (Trimble UX5), as part of larger surveying project.
The drone has a 1 metre wingspan, a rear propellor and weighs 2.5 kg. It was flown directly above the animals at an altitude of 120m. Video recordings were analysed by the research team in ten second sections.
They found that, although horses did respond to the presence of the drone, they did not show escape responses, which would have been expected in ground surveys or traditional low-level aerial surveys. Feeding, traveling, and vigilance behaviours increased, while resting and grooming decreased in response to the drone flight.
The researchers also observed the reaction of bison to the drone. Bison also showed increased feeding and travelling and decreased resting and grooming.
Reporting their findings in the journal Drones, the authors suggest that “the drone used in this study might have been perceived by horses and bison as low risk, possibly given the high altitude and small drone size. Our results showed that individuals did not display escape behaviour, and even increased feeding activities in response to drone flights at 120 m above ground level.”
They conclude that that drones “may serve as an appropriate tool for surveys of these species with low levels of disturbance, unlike other stressful sources.”
For more details, see:
Feral Horses and Bison at Theodore Roosevelt National Park (North Dakota, United States) Exhibit Shifts in Behaviors during Drone Flights
Javier Lenzi, Christopher J. Felege, Robert Newman, Blake McCann and Susan N. Ellis-Felege
Drones (2022), 6(6), 136.