With a population of about 2,400 elk living in the Estes Park area, it’s no wonder why these massive animals are a major attraction for visitors to Rocky Mountain National Park and Estes Park. Fall is an especially popular time to enjoy viewing elk and listen to the bulls bugle.

To some, the mating period, known as “the rut,” is as synonymous with autumn in the mountains as is the changing color of aspen leaves. It’s a season marked by the sounds of the elk, as well as the sights. Beginning in mid September and continuing through October, the mating call is known as bugling – a bellow that escalates to a squealing whistle that ends with a grunt. That’s how the bull advertises his fitness to cows, and warning to other bulls to stay away.

It’s also a time when the bulls become aggressive as they become more and more protective of their herds. Visitors are reminded to keep their distance. If you cause the animal to move, you are too close.

During the rut, a dominant bull gathers cows in a harem, to which he claims all breeding rights, a right usually not relinquished without a fight. Gathering a herd of cows is sometimes made easier by fighting another harem bull and taking away all his cows.  

The gathering of a harem is not the end of a bull’s herding effort. He must constantly work to keep his cows together, commonly moving their cows by threat and a push or shove. A bull will cut off a wandering cow just as a cowboy on horseback cuts off a steer by quickly quartering around the straying animal and bringing it back to the herd. However, it should be recognized that a cow stays in the harm by her own volition. If she chooses, she bolts from the herd and associates with another bull.

The biggest bulls are animals in prime physical condition and may be six to eight years old. Younger bulls may try to butt in – they are physically able to breed by their second summer – but they seldom get a chance to mate.

When the rut begins, bulls begin to bugle. The sounds they make are among the more haunting and beautiful in nature, as memorable as the howls of wolves and calls of loons. A cow listens to the bugle for clues about the bull’s size. A bugle, like a human voice, varies with the individual, but the older, larger bulls usually bugle more loudly than their young rivals. Their bugles advertise their presence and fitness to both females and other males. They also bugle to announce or accept a challenge from another male.

The rut takes considerable energy. During the summer, bulls spend their time feeding in preparation for the energy needs of the rut and winter. Summer feeding is especially important since bulls eat little during the rut which lasts four to six weeks. A mature bull may lose 20 percent of his body weight during the rut. After the rut, a bull, even if he eats to replenish his energy reserves, may be so depleted he cannot survive the upcoming winter.