Eric Pierre's Image

Eric had been tracking Arctic wolves on Victoria Island, Canada, when his guide spotted a herd of muskoxen some 5 kilometres (3 miles) away.

Approaching, Eric could see that the herd was nervous, probably because wolves were also on its trail. So he made a detour and stopped about 1km (half a mile) away upwind. Suddenly, he realized that the herd was now running towards them, oblivious of them. 'I've seen muskoxen run away,' says Eric. 'I've seen them react to a threat by forming a circle, and I've even seen a male charge. But I've never seen a herd spread out into a charging line like this. I could hear the thundering of their hooves. It was one of those situations where it really mattered that I made the right choice between technical accuracy, aesthetics - and security.'