This clip is from Rocky Mountain National Park Elk rut in October of this year. This is again one of those things that you just cannot understand if you haven’t seen and heard it. I don’t know if other species exhibit this strange behavior but it is certainly unusual.
The bulls acquire a harem of cows numbering around 20 by growing huge racks of horns, rolling in mud to look bigger and giving off the piercing screech they are famous for. Actually the cows choose the bull with whom they mate once and then leave. They spend the winter and spring with other expecting cows for protection.
These videos were taken just before and after dawn so the light is not ideal but you can get a flavor of the antics of the bulls during the rut anyway.