The game park where I do my photography practicing has all the elk it wants so they gave all the bulls vasectomies, so they still grow antlers but can't impregnate the cows. Since the cows aren't ever successfully bred, they come into heat several times over the course of the fall and early winter months. Sporadic rutting behavior can be seen during that entire time. The bull in the photo never made a sound, but I got lucky and captured the pose.