This photograph, taken in the Spanish Creek region, near Bozeman, Montana, is made by the 18-inch snowstorm that had died out only 12 hours previously.It was late February and locals said that this was the biggest storm of the winter: so we were fortunate to be on site and fully prepared. The snow cover here tends to be less substantial than up towards Big Sky and we needed that snow cover. Whilst there is no more important variable in our planning than rigorous attention to trusted weather forecasts, we sometimes have to acknowledge that luck plays a big role. This was a lucky day.

I think that any portrait of a bull bison, in which this enormous and emblematic animal is perpendicular to the camera, must be more kinetic than a head on portrait, simply because there is no sense of engagement. The bison is behaving as normal and not reacting to my presence because I was hidden behind a rock. He may have smelt me but he did not see me.

It’s the small things that can sometimes elevate a picture. In this case, it’s his eye detail and then immediately below his face, the blades of grass caked in frozen snow. There is an emphatic sense of the cold, which is what I always strive for in my bison work. A similar portrait shot in summer would lose zest and a powerful narrative. Fresh snow is certainly a photographer’s friend.