Risk-enhancing behaviors associated with human injuries from bison encounters at Yellowstone National Park, 2000-2015

Abstract

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 activities, 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 prevention 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 campaigns might reduce injuries at Yellowstone.

Keywords: Behavior change; Bison; Injury prevention; National Park Service.

Fig. 1

Informational sign on bison safety at a visitor use trail in Yellowstone National Park. The sign provides information on how to stay safe around bison by keeping an appropriate distance (>25 yards) and never approaching bison. This sign is an example of Yellowstone’s extensive educational outreach campaigns on wildlife viewing, which includes flyers, signs, website information, exhibits, videos, films, and social media, in addition to in-person contacts.

Fig. 2

Number of bison-related injuries by year—Yellowstone National Park, 2000–2015 (N = 25). During 2000–2015, a total of 25 persons were injured by bison. The number of human injuries from bison encounters varied by year (range: 0–5 persons injured/year) with 2015 having the highest number of injuries (n = 5).

Fig. 3

Bison-related injuries by month of occurrence—Yellowstone National Park, 2000–2015. All bison-related injuries occurred during April–October, with most injuries occurring in June (n = 7; 28%) and July (n = 9; 36%).

Fig. 4

Locations of bison-related injuries—Yellowstone National Park, 2000–2015 (N = 25). Circles represent general locations of human injuries from bison encounters at Yellowstone. The larger the circle, the more injuries that occurred in that area of the park. One injury report did not include a location and is not shown on this map. Dark and light gray shaded areas represent locations of bison herds in summer (dark gray), fall/winter (light gray). All human injuries from bison encounters occurred in developed areas, such as hiking trails, geyser basins, or near campgrounds. The Old Faithful geyser area had the highest number of bison encounters with seven injuries reported. Developed areas have the highest concentration of visitors but not the highest concentration of bison. The majority of human injuries occurred in summer when the majority of the bison herd is in breeding areas (depicted in dark gray), and a limited number of bison are in developed areas.