An amazing video has emerged of a bison sheltering her newborn calf during a sudden hailstorm in Yellowstone National Park, US.

The footage, captured by a passing motorist late last month, shows the incredible moment the mother - trailing an afterbirth - stood guard over her calf while huge hailstones rained down on the pair.

Writing online about the video, the filmer said: "As tennis ball-sized hail began to fall near Lamar Valley in Yellowstone National Park, we had to pull our vehicle over. A bison herd stampeded to get away from the hail--except for a mother buffalo who had just given birth. Her calf could barely stand, let alone run away. With afterbirth trailing out of her, the mother stayed with the newborn calf in the hailstorm and provided urgently needed shelter to the calf. They both survived the harrowing ordeal."

An amazing video has emerged of a bison sheltering her newborn calf during a sudden hailstorm in Yellowstone National Park, US.

The footage, captured by a passing motorist late last month, shows the incredible moment the mother - trailing an afterbirth - stood guard over her calf while huge hailstones rained down on the pair.

Writing online about the video, the filmer said: "As tennis ball-sized hail began to fall near Lamar Valley in Yellowstone National Park, we had to pull our vehicle over. A bison herd stampeded to get away from the hail--except for a mother buffalo who had just given birth. Her calf could barely stand, let alone run away. With afterbirth trailing out of her, the mother stayed with the newborn calf in the hailstorm and provided urgently needed shelter to the calf. They both survived the harrowing ordeal."