The peak of elk rut in Rocky Mountain National Park generally lasts from mid-September to mid-October, although it is often possible to hear elk bugling into November. The scene of tens to hundreds of elk in one location, flanked by spectacular mountain scenery and fall colors, is hard for most folks to resist. The sounds of bull elk bugling add to the spectacle.
Research conducted in Rocky Mountain National Park by Dr. Jennifer Clarke and her students from University of Northern Colorado (UNC) suggests that elk bugles contain wide ranges of information. Some bugles simply communicate that the bull is in the area with his harem. Others communicate to the cows that they are straying too far from the bull or otherwise displeasing him. Still others communicate to other bulls that they are too close to his harem, and that he is willing and able to defend his cows. In contrast, both types of aggressive calls have lower pitched components in some parts of the call. Elk calls with grunts seem to occur less frequently (about 16% of the time) than calls without grunts. So far researchers have not determined what function the grunts play.
Research by Dr. Joel Berger of the Wildlife Conservation Society and the Bronx Zoo suggests that elk bugle more often and for longer periods of time, and that elk form larger aggregations in Rocky Mountain National Park than in parks such as Yellowstone where they have predators such as wolves and grizzly bears. Thus, if you want to try to decode the messages in elk bugles, or simply want to experience seeing and hearing the spectacle during elk rut, Rocky Mountain National Park offers unique opportunities.
A special thank you goes to Lisa Rinker, graduate student at UNC, for assistance in preparing this Fun Fact.