Unmanned aerial vehicles (UAVs), or “drones,” as many people call them, are becoming increasingly popular among everyone from hobbyists to scientists, but they appear to be having some unintended consequences. According to a report from the Washington Post, drones have been coming in closer contact with wildlife, and it appears to be making the animals stressed.

Conservationists and researchers use drones to study nature without disturbing habitats, and UAVs have been useful in collecting data and scaring off poachers. Photographers have been able to capture some truly amazing shots by quietly hovering above wildlife instead of chasing animals on foot.

As a result of the increased prevalence of drones in the nature world, however, the animals appear to be the biggest victims. Scientists at the University of Minnesota’s Department of Fisheries, Wildlife, and Conservation Biology released a study in the journal Current Biology that tries to quantify the effects of drones on the stress levels of black bears.

Postdoctoral researcher Mark Ditmer fastened cardiac “biologgers” equipped with GPS systems on collars to two mother bears with cubs, one hibernating female, and a young male via a collar to record their heart rates when a drone flew overhead.

They observed a noticeable increase in heart rate every time a drone flew by overhead. The bears didn’t move as the drone passed by, but their heart data suggests that they were truly disturbed.

The bears in the study lived in areas where humans had settled as well. Ditmer believes that wildlife in more remote areas will show an even greater stress response to drones. While UAVs can certainly make collecting scientific data easier, their unintended side effects may do more harm than good.