Fall elk

Fall in Yellowstone Park means rutting bull elk. It's mating season and the time when large bulls gather groups of cows called harems. The bulls watch over their harems in order to mate with the cows as they come into estrus.

Mature bull elk use a tremendous amount of energy participating in the rut each fall. Bulls will chase and collect cows in order to establish harems and then chase the cows some more in order to keep the harems together. Bull elk must remain vigilant in order to keep other bulls from stealing or mating with their cows.

During the rut bull elk will often vocalize, or bugle to announce their size, strength, and status.

               This herd bull has spotted another mature bull and is bugling to make his presence known.

If two bulls are evenly matched in antler and body size a fight may occur. Here the herd bull leads a rival away from his harem and into an open meadow.

The two bulls posture to show each other their antler size and demonstrate their physical condition.

Here the bull on the left feigns an attack, acting as if he may jab the other bull with his antlers.

Testosterone levels are very high and the tension is palpable, yet neither bull wants to fight if it can be avoided. It's better to win through intimidation than risk serious injury in battle.

In this case neither bull backed down and a brief fight ensued. The fight lasted less than a minute before the former herd bull was vanquished and chased off.

After his victory the new herd bull bugled to let all of the cows and any potential rivals know that he was now in charge.

Every year in the Rocky Mountains during September and October countless dramas such as this play out. If you ever get the chance to go out and see and hear it for yourself you will never forget it.