This powerful image of a large bull bison was captured near Old Faithful in Yellowstone National Park, Wyoming. It is as good as I can do and probably my most impactful animal portrait for some time. The bison is an emblematic North American animal that roamed the continent millions of years before man. When fully grown, it is a massive beast that deserves our respect and recognition.

When I was researching bison earlier this year, I quickly understood two things – firstly that some rogue bulls carry a serious threat if their space is invaded and secondly that the adult face is both prehistoric and enormous. The bison is all about the face and I sensed that any picture that didn’t recognise this, would miss my goals. My instincts were that the image also needed a sense of “Yellowstone in the winter” and this, combined with the need for proximity, all pointed to a ground level, remote control approach.

To work with ground level radio controlled cameras and a prime wide angle is very much my signature style, but it is easier with elephants in Amboseli, than bison in Yellowstone. This is not an easy location – our guide suggested that 95% of Yellowstone is out of bounds in winter. It is the most geothermally active park in the world, throw avalanches, wolves and bears into the mix and we have a primordial soup of creation.

I failed about 10 times with my camera positioning and I tweaked my lens/camera combination constantly. It was most frustrating and I was generally grumpy. But on the third day at about 2 pm, it all came together. The trees and the sky are most helpful additives – but what a face and what a back structure. I haven’t seen this sort of image of a big bison before.

I would like to thank Tom Murphy, one of America’s most acclaimed nature photographers, for assisting me on this assignment. We were both frustrated by the milder weather at the start of the week, but his knowledge and fireside tales of the area kept the spirits up. A good 20 years ago in the depth of a very cold winter, Tom – equipped with just a light tent – took a back country ski trip across the 100 km span of Yellowstone – a remarkable feat that truly humbles anything I have ever achieved and a trip that will soon be commemorated by a long awaited documentary film.