Drones used to monitor bears send their heart rates through the roof

Wildlife researchers have long struggled with removing the human element whenever possible, so as to monitor patterns like mating and migration without getting in the way. Hidden cameras help, but can only provide so much data. In recent years, camera-mounted drones have been considered for research, and the short-term data looked promising; in particular, anecdotal evidence suggested animals weren't changing their activity much with drones flying overhead.

A research team at the University of Minnesota wondered if anything unseen might be happening during drone studies. So they put biologger collars on four adult bears and two cubs, then flew drones an average of 21 meters above their heads (and an average of 215 meters absolute distance) for five-minute spans. The results, published in Current Biology on Thursday, included a noticeable heart rate spike for all flown-over bears while the crafts were overhead.

In those five-minute windows, one bear's heart rate climbed all the way from 41 beats per minute to 162, while the rest of the bears saw beats-per-minute jumps as low as 30 and as high as 80. Still, each bear had the spike in common, along with a resulting drop to a normal heartrate shortly afterward. This came despite a seeming lack of visible response, with the exception of one bear that appeared to react. The bears in the study included two mama bears and their respective cubs; a lone male bear; and a female bear on the verge of hibernation.