During the fall mating season, a herd bull will be acutely aware of any threat from other males that would challenge his right to breed. Often, a testosterone driven bull will lose all fear of humans if he thinks there might be another male in the same location. Even with the blinding light of the setting sun in his eyes, this bull came right up to within 20 yards of my camera until he could decide that there was not another elk lurking above him.