Most of us human-powered adventurers like to think we move through the wilderness with a minimum of impact. Leave no trace, right? That’s for motorcycles and ATVs and snow machines. Well, not so fast. A new study, or rather, a meta-study of other studies, found that the effect of human recreation on animals is tangible, substantial, widespread, and greater than previously thought.

The study was a joint effort by the Wildlife Conservation Society, Colorado State University, and University of California-Berkeley. It looked at 274 other studies worldwide and found that they documented human impact on animals in 93 percent of the cases, most of it negative. Surprisingly, signs pointed to non-motorized recreation having a greater negative effect that motorized.

Worldwide, visitation to parks and other protected areas now numbers eight billion a year. In the United States, visitor days to protected areas increased 32.5 percent between 2000 and 2009, while the number of visitors jumped 7.5 percent. The trend can be see around the globe, too—Latin America, Africa, and Asia also saw visitation growth between the early 1990s and mid 2000s.


“Outdoor recreation is typically assumed to be compatible with biodiversity conservation and is permitted in most protected areas worldwide. However, increasing numbers of studies are discovering negative effects of recreation on animals,” the study reported. “Although publication rates are low and knowledge gaps remain, the evidence was clear with over 93% of reviewed articles documenting at least one effect of recreation on animals, the majority of which (59%) were classified as negative effects…Counter to public perception, non-motorized activities had more evidence for a negative effect of recreation than motorized activities, with effects observed 1.2 times more frequently. Snow-based activities had more evidence for an effect than other types of recreation, with effects observed 1.3 times more frequently.”

As is typical of studies, the authors say that more study is needed to better understand the impact on animals, especially around the difference between motorized and non-motorized recreation and the great negative impact in winter. They speculate that winter is simply harder on animals—food is scarcer, moving away from backcountry skiers requires more energy, the margins for survival are thinner. They also speculate that engine-based recreation takes place in a larger area and is more diffuse. But, you know, more study is needed.

Photo by Brandon Levinger.

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