A bull bison rammed a 65-year-old grandfather in Yellowstone National Park, hooking him with its horn and tossing him metres into the air, in a dramatic encounter that has renewed warnings about the dangers of approaching wildlife. The incident, which was captured on video, saw the man flipped into the air before landing on his side. Witness Mike Macleod, who recorded the encounter, described how "the bison hooked him with his left horn on his hip and tossed him in the air", adding that the man "made a perfect flip and landed on his side." The National Park Service advises visitors to stay at least 25 yards from bison, animals that despite their placid appearance are powerful and can charge without warning. The timing added to the risk. Jennifer Barfield, a professor at Colorado State University, explained that during the mating season bison behaviour becomes more volatile, warning that the season "is really going to drive their behaviour" and make the animals "potentially more unpredictable than at other times of the year." The episode serves as a stark reminder to the millions who visit America's national parks each year that maintaining a safe distance from wildlife is essential to avoid serious injury.