Is it to ward off bugs? Nope. By fall, their hair keeps the nastiest of biters and stingers at bay. It must be to keep cool? Wrong again. Bulls will break through ice to wallow. Just as a prom-bound teenager will douse himself in cologne, bulls use wallows as a way to coat themselves in lustful olfactory bliss, hoping to be irresistible to cows in estrous.
During the rut, a bull’s urine becomes saturated with testosterone and any spring or boggy spot can become a wallow. A bull will rake the muck with his antlers, then unleash a veritable pheromone fury stream onto his mane and into the mud. Then the bull will flop around like a dog rolling on a dead fish. After his rut-funk is amply applied, he will many times rub his mane, chin and pre-orbital gland on nearby trees and often belt out a bugle—what he hopes is warning to other bulls and a siren song for the ladies.