Don’t mess with a bison. 

One gander at this humped, horned, heavy-headed bovid – the males of which can reach a ton or more – ought to make this clear enough. Again and again, though, visitors to North American national parks and wildlife refuges seem to fall under the illusion that these mighty grazers are just placid cows dressed in woolly robes – a dangerous misimpression, to say the least.

This is the thick of the bison rut in Yellowstone National Park, that rowdy season when mature bulls join large, mixed-gender herds to woo cows - as many as they can – and square off against rivals. A video posted to the park’s official Twitter feed illustrates just how intense this time of year can be. The footage shows one bull bison basically pummelling another off the road that runs through the park’s buffalo-trampled Lamar Valley: quite the demonstration of brute strength and riled-up aggression.

Actually, much of the competition between rutting bull bison takes the milder form of basically trying to out-swagger one another to avoid physical conflict. Like many other bovids, for example, they’ll perform broadside displays: walking or standing parallel to show off their full size, often with arched back, and accentuating their burly lateral profile by bellowing and pawing or horning the ground. They’ll also often wallow, raising great clouds of dust in a vigorous display of machismo. 

If such intimidation isn’t enough to persuade one or another to yield the scene, the bulls may resort to all-out battle. American bison have a hardcore fighting style: Bulls commonly charge directly toward one another and slam together headfirst, a high-impact clash that then may transition to head-on wrestling and horn-gnashing. It’s a style somewhat similar to that of African buffalo – though buffalo bulls often simply motor into one another without the followup tussling – and fairly distinct from European bison, or wisents, which don’t much charge and instead grapple with locked horns. (Wisent horns are more forward-facing than those of American bison, and thus better suited to this manner of sparring.)

The anatomy of a bull American bison is well set up for high-speed head-butting and wrestling. Its skull has broad, domed, strongly sutured frontals to better withstand and absorb direct head-on blows; the bison’s low-held head also more effectively transmits the impact force to the rest of its body, protecting the neck. Bull bison have a heavy shag of hair on their foreheads that cushions impacts, and also sport a thick coat on their front legs – their "pantaloons" or "chaps" – that, in addition to beefing up their apparent size while displaying, offers protection from rivals’ horns that might plough through into their forequarters.

Nonetheless, injuries certainly aren’t uncommon during these bison rumbles, and some of them are ultimately fatal.

The Yellowstone clip doesn’t so much depict an all-out tussle between bull bison as underscore just how powerful and swift these huge beasts are. It’s not only the time for bison rutting in the American West, but also high season for tourists to ill-advisedly (and illegally) get way too close to these biggest of North America’s land mammals, which experts say people should stay at least 25 yards away from.

Last month we shared footage of a woman "playing dead" in the face of a defensive Yellowstone bison; more recently yet, a motorcyclist in South Dakota’s Custer State Park was hooked by a bison and violently spun around. In July, a teenager in Theodore Roosevelt National Park in North Dakota’s Little Missouri Badlands was gored and hurled off the ground when he hiked between two bulls that had been duking it out.

"It just kind of was running, and then of all of a sudden he just throws me into the air," the teen told ABC News. "And I was flung about six feet into the air [...] I landed on my backpack, which saved my life."

A similar incident from Yellowstone in 2019, captured on film, saw a young girl tossed by a bull bison:

(The nine-year-old victim was treated for her injuries and released.)

Now, go back and watch the Yellowstone video up top: See how easily the one (giant) bison bull shoves the other (giant) one nearly off its feet? You’re a lot smaller – and a lot slower – than that bullied buffalo. In conclusion, folks: Don’t mess with a bison.


Top header image: Tupulak, Flickr