bison on half-alert

This solitary bison had been sheltering under the only large tree in the area when I first saw it. After about 20 minutes it wandered into the open, but it did not move in a direction that would put light on its head or flank. With dark eyes surrounded by dark brown fur, seeing the eye of this magnificent beast is a challenge. The half-raised tail indicated that he was aware of my presence, and that I should not come closer. An erect tail would tell me it was time to back off, quickly.