Guide Adam Brubaker was leading a group in Yellowstone's Hayden Valley
They spotted a grizzly stumble across a pack of wolves as it was foraging
The bear reared up on its hind legs to get a better view
As many as ten wolves circled the grizzly before escorting it into the trees
The wolves may have been protecting a fresh kill or nearby cubs
A tour guide captured the moment a grizzly bear was surprised by a pack of wolves in Yellowstone National Park.
Adam Brubaker of Tied to Nature tours was taking a group through Yellowstone's Hayden Valley on Friday when they came across the carnivorous encounter.
At one point, the bear reared up on its hind legs to get a better look over the tall grass.