Watch Huge Male Yellowstone Bison Spar on Snow-covered, Foggy Road

Incredible footage of two large male bison sparring on a frozen road in a foggy Yellowstone National Park has been captured by a tour guide.

John Clark has worked as a guide in Yellowstone for the last five years. He was on his way to the Snow Lodge at Old Faithful to collect some clients for a tour when he came across the two bison mid-fight.

He told Newsweek the two bison fought for between five and 10 minutes. In the video, they can be seen butting heads and shoving one another back and forth across the snow-covered road.

"I see some incredible things in the park," he said. "I like winter best."

There are almost 5,500 bison in Yellowstone National Park, split into two breeding herds. The northern herd has around 4,000 members, while the central herd has about 1,300.

In the summer they are found across the park's grasslands, but in winter, as Yellowstone freezes, they are found around the hydrothermal areas, the Tower and the Gardiner Basin, along the Madison River and the Blacktail deer Plateau.

Males, which can weigh up to 2,000 pounds, are often seen sparring during the rut, when bison come together to breed. Males will show their dominance by bellowing, kicking up dust, rolling around on the ground violently. Sparring involves butting heads with other males.

During the rut, the dominant male wins the right to mate with females.

Winter fights are less common, and can be the result of two younger males testing out their strength.

"They will do this [spar in winter] occasionally to show dominance but mostly in Summer during the mating season," Clark said. He said the loser of the fight eventually got pushed off the road.

"Bison are usually grazing 9-11 hours a day [in winter]," Clark said. "Winter is a rough time for them foraging for food. This would rate up there as one of my best experiences because I was by myself."

Clark said the most amazing encounter was at the end of last year, when he filmed wolves feeding on an elk carcass at the side of the road in the pouring rain.

Bison have lived in the U.S. for thousands of years. They once roamed across the Great Plains, but were almost wiped out by hunters in the 1800s.

By the start of the 20th century, just two dozen individuals were left in the Yellowstone herd. Extensive conservation efforts have seen their numbers rebound, and the population is now carefully managed by park officials.