The scientists published their findings in the journal PLOS ONE. The researchers studied elk (Cervus canadensis) in Alberta, Canada. The results come from a year-long study that tracked 424 herds and 870 individuals on public, private, and protected land. The scientists observed the animals from a safe distance and recorded their behavior. They researchers found that humans accounted for the greatest degree of disturbance to the elk, even more so than natural predators, such as wolves, cougars and grizzly bears. When elk encountered humans, especially on public lands where hunting and ATV use was permitted, the animals snapped quickly into vigilance mode, scanning for danger. One car passing every 2 hours was enough to induce this behavior, which detracts from feeding and leaves females in a less healthy state for breeding. “Humans are playing the same role as a natural predator, but probably at even higher levels,” states Simone Ciuti, a behavioral ecologist at the University of Alberta, and lead author. Ciuti and her colleagues plan on investigating how different human activities, like hunting and hiking impact the animals’ behavior. They also plan on finding out whether this applies to species like caribou (Rangifer tarandus), possibly helping to explain the caribou’s decline in recent years. Reference: “Effects of Humans on Behaviour of Wildlife Exceed Those of Natural Predators in a Landscape of Fear” by Simone Ciuti, Joseph M. Northrup, Tyler B. Muhly, Silvia Simi, Marco Musiani, Justin A. Pitt and Mark S. Boyce, 28 November 2012, PLOS ONE.DOI: 10.1371/journal.pone.0050611