"The drone was such an asset that I couldn't imagine doing the job without it," researcher Wesley M Sarmento said.

Remote-controlled drones could help reduce human-bear conflicts by scaring away grizzly bears without resorting to shooting.

Brown bears roam across much of the northern hemisphere from the mountains of Spain to the prairies of the US. These bears are formidable carnivores that can weigh up to 751 kg (1,656 lb) and have claws 15 cm (6 in) long.