When Congress passed the Wilderness Preservation Act of 1964, they defined "wilderness" as an area "untrammeled by man." The thinking was that if only certain activities like hiking, camping and biking were permitted in a space, the human impact would be negligible. But a new study published on March 3 in the open access journal PLoS ONE shows that even these minor activities alter the ecosystems we want so badly to preserve.
A group of researchers at the University of Calgary in Canada placed more than 40 cameras on hiking trails and roads in the Rocky Mountains in Alberta to observe how even mild human traffic alters the ecosystem. They found that on roads and trails trafficked by more than 18 visitors a day, large predators like wolves, black bears, grizzlies and cougars were less abundant than they would be in the wild. Furthermore, they found that on roads trafficked by more than 32 people a day, the number of small prey increased by 300%.