Battle Between Grizzly Bear and Bull Elk Filmed in Yellowstone National Park

A video showing a battle between a grizzly bear and a bull elk has been filmed in Yellowstone National Park.

The footage captures the elk fleeing into Yellowstone River at Hayden Valley while being pursued by a large grizzly. As the bear gets closer to the elk, it turns and defends itself with its antlers, but the bear avoids them and grabs hold of the elk's back.

The elk tries to shake the bear off but appears to get weaker in its efforts over time. The elk moves into deeper water where it becomes unstable and loses its footing. The bear then struggles as it tries to pull the lifeless elk to the shore.

The video can be viewed on YouTube: Grizzly Kills Bull Elk In the Yellowstone River, Hayden Valley, Sept.18, 2020

BE Judson, who posted the video to YouTube, said he was "startled" by the attack, which took place in the early morning. "The grizzly was successful in taking down the bull elk after only a few minutes, but it worked for around a half an hour to redirect it to the far side of the river and secure it on the east bank, about one hundred yards downstream from the north end of Hayden Valley," he wrote.

Male grizzly bears can weigh up to 700 pounds, while females can reach around 400. There are about 150 with a range either entirely or partially within Yellowstone National Park.

Grizzly bears in Yellowstone come out of hibernation between March and May and their diets vary by month. From this time they tend to feed on elk, bison and other ungulates in the park. According to the National Park Service, these tend to be animals that died over the winter or elk calves that the bears can kill. By mid-July, bears are "rarely able" to catch elk calves, and tend to have a more plant-based diet, including thistle, grasses and dandelion, as well as ants and army cutworm moths.

However, some grizzlies will attack adult bull elks during the fall elk rut. This is the elk breeding season and it normally lasts just over a month, beginning early September. Elks gather together, with the bulls producing calls to attract mates and to challenge other males. Battles involve males wrestling with their antlers, crashing into one another. Serious injury is rarely sustained in these encounters, with the weaker bull normally giving up and leaving.

However, rutting season can pose a big threat to human visitors in the park. Earlier this month, Yellowstone officials warned people to stay at least 75 feet from elk. If one charges, it advised to find shelter in a car or behind a sturdy barrier as fast as possible.

yellowstone grizzly
A grizzly bear in Yellowstone National Park in 2005. A recent video has shown a grizzly bear taking down a bull elk in Yellowstone River. William Campbell/Corbis via Getty Images