
A photographer in Wyoming captured the bone-tingling moment he was sized up and charged at by a one-tonne Great bison.

Willis Chung took the epic picture just seconds before he was forced to abandon his photography equipment as the bull sprinted towards him.

The startled 56-year-old remarked: 'I never intended to become an object of curiosity to the bull!'

Look out! Willis Chung photographed this spectacular moment that the bull, surrounded by swirling dust, sized him up with a mean stare before charging in his direction

The one-tonne bison from a different angle later trotted over to check out Chung's camera and tripod

It rolled over in the dirt of Yellowstone National Park to scratch places that cannot be reached

'The bull rocked to its feet, snorted, and trotted over directly towards me,' said Willis, describing the incident.

'I knew my best choice was to head 90 degrees away from the bull's path, constantly changing my direction to keep moving perpendicular to the bull's path.

'I went to my left, yelling "Yea ha!" at the top of my voice and opening my arms wide to look bigger.

'The bull steered off to the right and I continued to the left as we made a circle around the camera and tripod I had decided to leave behind.'

Chung, from Denver, decided to stand the recommended distance away from the beast after it charged at him

Strike a pose: The bison showed an interest in the camera which was almost set at its eye level

A close-up of the bull at Yellowstone National Park, which is home to an estimated 5,000 bison

Yellowstone measures 3,472 square miles and is home to around 5,000 bison, as well as housing bears, wolves and moose.

Although they may appear relatively docile, bison's can become very aggressive when disturbed and have the ability to run at over 30mph.

Willis, a physician from Denver, stuck around to take more photos of the bull that was seen wallowing and rolling around in the dust to scratch an itch.

He has been shooting 44 years, often at Yellowstone, but never had an experience like the one he encountered.

'Taking 10-15 minutes to sit quietly invites the animals to come out and once they see me as part of the landscape, they often behave in surprising and lively ways,' he said.

'Making sure I wasn't going to be perforated was my chief priority for a little bit.

Chung said he went for a long tea break after being left 'a bit shaky' by the encounter

He advised anyone who finds themselves facing a bison: 'Make sure you have an escape plan!'

'Once I got to a decent distance I was a bit shaky.

'Some ask me what I did afterwards, which was take a long tea and lunch break and send thanks to whoever was watching over me from above!'

When asked what words of advice he would give to others in this situation, he said:

'Plan ahead! Have an escape plan and be willing to leave your gear behind!'