By Sajad Ghanbari and Samuel Turvey.

By Mira Sytsma, Tania Lewis, Beth Gardner, and Laura Prugh.

This Plain Language Summary is published ahead of the article discussed; check back soon for a link to the full paper.

Visits to national parks have grown steadily over the last decade, and these protected areas are often key venues for outdoor recreation and activities such as wildlife viewing. But what level of human activity in these protected areas is “too much” for wildlife? How can we measure this? And is there some threshold level of human activity above which the human activity displaces wildlife?  

Glacier Bay National Park in southeast Alaska offers us the unique opportunity to answer those questions. Glacier Bay has very low levels of on-land tourism (most people come by boat and often don’t ever go to shore)—making it a particularly interesting place to identify a lower level of outdoor recreation that changes wildlife behavior. In this study, we used remote cameras to measure how brown bears, black bears, wolves and moose use areas of high, concentrated human activity versus areas visitors use less. By controlling where and when humans could access certain areas of Glacier Bay and then measuring wildlife responses to the differing levels of human activity, we identified two important thresholds.

First, we did not detect the any of the four species on the remote cameras more than five times per week unless human activity was absent. Second, in backcountry areas, wildlife detections on the cameras dropped to zero per week once outdoor recreation levels reached the equivalent of about 40 visitors per week. For context, some of the most highly visited national parks in the United States receive upwards of 200,000 people per week.

But it’s unreasonable to expect that protected areas like national parks will be completely devoid of human activity—especially as the number of people seeking to visit wild places increases—and it’s up to managers of these areas to balance the desires of humans to view wildlife with the likely impacts. A combination of management techniques, including concentrating human use in certain areas to limit the areal extent of human impacts, or limiting the time of year or day that people are allowed to visit specific areas, might be the best way to promote coexistence between people and wildlife in protected areas.