The American Bison, often called buffalo, is the largest land mammal in North America. Its sheer size and speed make it a formidable animal that must be treated with extreme caution. Bison are not inherently aggressive, but they become defensive when they feel threatened, which frequently occurs when humans get too close. In high-traffic areas like Yellowstone National Park, bison are responsible for injuring more visitors than any other animal, including bears and wolves. The danger they pose is less about active hunting and more about their powerful, unpredictable reaction to perceived human intrusion.
The Physical Profile of a Threat
The threat posed by a bison begins with its imposing physical dimensions and deceptive athleticism. A mature bull can weigh between 1,800 and 2,400 pounds and stand up to six feet tall at the shoulder hump. This massive bulk is concentrated in the head and shoulders, supported by a powerful neck and the prominent hump, which contains muscles allowing the animal to sweep its head through deep snow and deliver devastating blows. Despite their lumbering appearance, bison are surprisingly agile and fast, capable of running up to 35 miles per hour. This speed is nearly three times faster than the average human sprint, meaning that outrunning a charge is impossible. Both males and females possess short, sharp horns designed to gore or toss a perceived threat with immense force.
Behavioral Triggers and Context
Bison are most often provoked into aggressive behavior by feeling cornered, crowded, or surprised by a lack of space, which happens when people disregard their need for distance. They communicate rising agitation through recognizable physical warnings that should be acted upon immediately. A calm bison’s tail hangs relaxed, but if the tail raises straight up like a flag, it indicates the animal is on high alert and may be about to charge. Other warnings include lowering the head, shaking it back and forth, and pawing at the ground. Seasonal factors increase the risk of aggressive encounters. During the calving season in the spring and early summer, cows are highly protective of their young. The mating season, or rut, which occurs from mid-July through September, makes bulls more territorial and unpredictable as they engage in dominance displays.
Statistical Reality of Bison Encounters
The danger posed by bison is demonstrated by the frequency and severity of human injuries in areas with high bison populations. Between 2000 and 2015, 25 people were injured by bison in Yellowstone National Park, with the majority of incidents occurring in June and July. The injuries are severe, as bison attacks generally involve butting, goring, or tossing the victim into the air. Trauma includes broken bones, internal organ damage, and severe blunt force trauma from being struck by the animal’s massive head. Data indicates that the vast majority of these incidents are preventable, as most injured individuals actively approached the bison, often attempting to take photographs, before the animal reacted. The average distance before the injury occurred was extremely close, often only a few yards.
Maintaining a Safe Distance
The most effective strategy for avoiding a dangerous encounter is to respect the bison’s space and maintain distance. Park regulations require visitors to stay at least 25 yards, or 75 feet, away from bison at all times. A more conservative distance of 100 feet or more is widely recommended, which provides a greater margin of safety. If a bison stops its activity, raises its head, and focuses its attention on you, it is a clear sign you are too close, and you should slowly back away. Never attempt to approach, feed, or crowd a bison, even if it appears calm or docile. Respecting their space ensures they do not perceive you as a threat, which guarantees a safe viewing experience.