National Park Service


Date of this Version



One Health 6 (2018) 1–6


© Published by Elsevier B.V.

Open access


Yellowstone National Park is home to the largest bison population on public land in the United States. Although Yellowstone regulations require visitors to remain at least 23 m from bison, since 1980, bison have injured more visitors to Yellowstone than any other animal. We examined a series of bison-related injuries at Yellowstone to evaluate the circumstances of these injuries and to identify common risk-enhancing behaviors that lead to injury. To do this, we analyzed narrative case incident records from law enforcement regarding bison-human encounters in Yellowstone during 2000–2015. Data regarding demographics, preencounter ac- tivities, number of persons involved, type of injury, and acknowledgement of appropriate viewing distance were extracted from the records. Bison encounters resulted in injury to 25 persons (21 visitors and 4 employees). Age range for injured persons was 7–68 years (median: 49 years), and 13 were female. All injuries occurred in areas of high visitor concentration. Mean visitor distance from bison before injury was 3.4 m (range: 0.3–6.1 m). Twenty persons (80%) actively approached bison before their injuries; 5 (20%) failed to retreat when bison approached. Fifteen persons (60%) were injured when in a group of ≥3 persons approaching bison. Twelve persons (48%) sustained injuries while photographing bison. Six persons (24%) acknowledged they were too close to bison. Education alone might not be sufficient to reduce bison-related injuries. Effective injury pre- vention campaigns for national parks require an understanding of the behaviors and motivations of persons who approach bison. Including behavioral science and behavior change techniques in bison injury prevention cam- paigns might reduce injuries at Yellowstone.