It starts in early September (sometimes late fall). Bull elk suddenly become interested in cow elk and round up harems.
The bulls will roll around in mud and their own urine. They show off their toughness by hanging weeds and branches in their antlers - the smellier and dirtier, the better. Their bugling wail can be heard across the valleys.
The bull elk expend a lot of energy in autumn to keep their harem together and warn off contenders.
Learn more about the elk rutting season in Rocky Mountain National Park.