People are drawn to bison without quite knowing why. Seeing them stirs something old. Something nearly lost. There is wonder in it. And hope.

~Chris Geremia, in Yellowstone Bison, Return of the Last Wild Herd, 2026

The bison rut is reaching its peak here in the park and it seems there is just not enough time to take it all in. A couple of days ago Melissa and I went out with one goal – observe bison as they engage in their annual courtship behavior known as the rut. The bison rut typically begins in mid to late July and runs into early September with the peak being a couple of weeks in early August. Cows and calves have formed large herds and the bulls are following and courting females. Many bulls have picked a cow (for now) and are following her every movement, guarding her against other bulls, and directing where she can and cannot go. Melissa thinks they are bullies:)

The rut is both a visual and auditory spectacle unlike any other and the deep bellows of the bulls are resonating across the landscape in places like Lamar and Hayden Valleys and Little America. A key feature of the rut that is easily seen in these grasslands is the wallowing of the bulls. Wallowing is where a bison picks a spot (usually an existing bison-sized depression in the soil created by years of bison wallowing) and flops down on its side and kicks and partially rolls onto its back. They really can’t roll all the way over because of their huge shoulder humps. Wallowing is done throughout the year when the land is not snow-covered as a way to reduce biting insects, regulate body temperature, and leave behind their scent. Cows also wallow. During the rut, wallowing takes on some extra significance for the bulls – it signals their dominance and strength. While we observed the herd, a bull would often bellow on the approach of another bull and then paw at the ground, flop down hard, and wallow, kicking up dust as he did. In fact, looking across the landscape this time of year you see countless dust clouds from bison wallowing.

–A live speed video clip of a bull bison wallowing. Note the numerous deep bellows he makes to let other bulls know he is a dominant male.

The rut is about strength and endurance. Slow motion video seems to help accentuate the power of a bull’s motions. Unfortunately, it does not include audio in this format on my camera. Here are a couple of clips showing that strength.

–A bull rolls in the dust marking himself and the ground with urine to leave his scent behind

–A complete wallow ending with a shake of his massive head that sends out a cloud of dust.

I bet if the other bulls could see their rivals in slow motion, it might be a deterrent to engaging in actual combat. Right now, it seems like it is mainly a show of strength and posturing to help minimize battles. When a bull approached another tending a cow, the latter bull often bellows, wallows, and then steps out in the direction of the approaching intruder. That is usually enough to cause the approaching bull to change direction or for the tending bull to decide it is not in his best interest to continue courting that particular female. We hope to get in a couple more days of bison watching before the rut concludes in early September. And there are many more adventures ahead, so stay tuned.