The bugle of the bull elk is the music of autumn in Colorado's high country. During the fall mating season, bulls bugle to collect harems of cow elk, advertise their readiness to breed, challenge, or warn other males, and sometimes just to let off a little emotional steam.
The breeding season, or rut, gets underway in mid-September and lasts through late October, though bulls may begin to bugle as early as mid-August and continue through November. Once heard, the eerie call is not easily forgotten. It starts as a low-pitched bellow, rising to a high, clear bugle tone, ending with a series of grunts.
Mature bulls gather together groups of cow elk for breeding. Dominant bulls attract the most cows, though competing bulls continuously try to lure the cows away. Once a bull has accumulated females (along with their calves), he keeps busy driving away competitors as well as keeping together the cows, who have a tendency to wander off.
The heightened hormonal level in the male produces various behaviors in addition to bugling. The bulls become hyperactive, belligerent, and competitive with other males. They are usually less wary and may therefore be seen more easily. There is a pronounced drop in food intake as the animals devote their time and energy to mating. Males may follow females with necks outstretched, muzzles raised, and upper lips curled. They “shadow box” bushes and saplings with their antlers and dig rutting pits into which they urinate and then wallow. Occasional battles between males may occur, the combatants lowering their heads and sparring with their impressive antlers, but most encounters consist mainly of bluff with much noise and display of headgear.