Elk mating season, also called rut, has begun at Yellowstone National Park. Two bull elk were seen already clashing antlers in a battle of dominance. | USA TODAY

53K views · 1.7K reactions | During the rut, bull elk gather cows and calves into small groups called harems. They bugle and rub trees, shrubs and the ground with their antlers to attract cows and intimidate other bulls. #WildlifeWednesday | Colorado Parks and Wildlife | Facebook

The elk mating season (rut) generally occurs from early September to mid-October. Bull elk bugle to announce their availability to females (cows) and to warn other bulls. When answered, bulls move toward one another and sometimes engage in battle where they crash their antlers together and wrestle for dominance. It is a dangerous time as bull elk will consider people and cars threats and charge. Always keep your distance and, if charged, retreat to shelter in a building or vehicle as quickly as