“As Autumn approaches, elk descend from the high country to montane meadows for the annual breeding season. Within the gathering herds, the larger antlered males, weighing up to 1100 pounds and standing five feet at the shoulder, move nervously among the bands of smaller females.
In this season of excitement, bull elk compete with one another for the right to breed with a herd of females. Prime bulls, eight to nine years old, stand the best chance of mating. While competition is high among bulls it includes little fighting, since fighting causes injury and depletes energy. Instead, mature bulls compete for cows by displaying their antlers, necks and bodies. They emit strong, musky odors and bugle. With little rest or food during the mating season, bulls enter the winter highly susceptible to the hardships of the coming months.
Bull elk signal the season of mating with a crescendo of deep, resonant tones that rise rapidly to a high-pitched squeal before dropping to a series of grunts. It is this call, or bugle, that gives rise to the term “rut” for the mating season. Rut is derived from the Latin word meaning roar.
The eerie call, echoing through the autumn nights, serves to intimidate rival males and may act as a physical release for tensions of the season. Cows and younger bulls may also bugle, but they are unable to match the strength or range of the older bulls’ calls.”
– National Park Service