Human activity creates 'refuge' for prey: study

A new study from the University of Calgary suggests you might be saving an animal's life when you take a walk in the woods.

The study, published in the journal Public Library of Science One Wednesday, found that while predatory animals like wolves, cougars, and bears tend to stay away when humans are in the area, prey like elk, moose, and deer are more likely to stick around.

"Once a certain level of human activity occurred on a road or a trail, then it seemed to be there was less likely to be a carnivore there," said Tyler Muhly, one of the authors of the study, who recently completed his Ph.D. in environmental design.

The research team deployed 43 digital camera traps at random locations along roads and trails on the eastern slopes of the Rocky Mountains in southwestern Alberta from April to November 2008 to examine how the presence of humans affects the relationship between predator and prey in the wild.

Large predator animals in the study area consisted of wolves, black bears, grizzly bears and cougars, while the large herbivore species monitored were moose, elk, white-tailed deer, mule deer and cattle.

Their results showed that prey were three times more abundant on roads and trails used by more than 32 humans a day, but predators were less abundant on roads and trails used by more than 18 humans a day.

Muhly said the presence of humans essentially creates a kind of refuge for weaker animals.

"We often think about the direct effects that humans have on a species," he said. "If we're going to go out on a trail, we might think, 'I might be scaring away a grizzly bear or something,' but we don't often think at the same time we might be creating some kind of refuge from grizzlies."

It's important for humans to realize the impact they can unwittingly have on the food chain, Muhly said.

"Humans are putting more demands on the ecosystems and the population is growing, so I think we have to think about these broader effects, not just the obvious ones, when we're doing any kind of land use planning."