YELLOWSTONE — Ah Bison, the “friendly and docile” fluffy cow-like animal that has been roaming freely in Yellowstone since prehistoric times, acting as a staple icon to the American West.

Although at first glance this animal can easily be compared to a cow, many people don’t see the sheer size and power that it holds. Bison have been fighting off predators like bears and wolves for thousands of years. So naturally, there’s a little bit of ferocity underneath that funny looking hairstyle.

“The bison rut is in full swing,” Yellowstone National Park Service (YNPS) said on Facebook. “You may see male bison with their mouth open, tongue out and upper lips pulled back. This is called a flehmen response and it draws air into an olfactory organ on the roof of their mouths. This is how bull bison sniff pheromones and determine whether a female is ready to breed.”

Once those pheromones are detected, bison begin ruffling up dirt and charging into each other to compete for dominance and ultimately a mate. During the rut, bison can be much more dangerous and aggressive than they normally are. This recent video that YNPS shared on social media is proof.

YNPS added, “Bison mating season is still going on in the park. Male bison are particularly aggressive right now, though all bison and other wildlife can be dangerous. Remember to always keep your distance—25 yards from bison and elk; 100 yards from all other wildlife.”

Fun Fact: Often referred to as buffalo, bison got their nickname from early explorers who thought the large ungulates resembled the African water buffalo.