In Alaska and the more open terrain of northwestern alpine meadows and muskeg habitats, a rutting bull will flash and flag his massive antlers like “social semaphores,” as described by renowned antler scientist Richard Goss. Rocking his rack side-to-side, he deliberately displays their shape and size to both attract mates and warn off male competitors. Here in our heavily treed boreal and temperate forests, the eastern (or Canadian) moose uses his palmate antler surfaces like satellite dishes to amplify the distant wavering calls of a cow in search of courtship. But that’s not all. He thrashes pliant shrubs and saplings and rubs larger trees while deliberately clonking his antlers against them. In this way, he uses auditory marking to announce his reproductive intentions and his dominance to cows and other bulls alike. Eastern Native American moose hunters mimicked these antler sounds by using a moose scapula to create similar scraping, banging, and brush-breaking noises, which could often be relied upon to draw a moose out of cover.
For a bull in the near company of an estrus cow, wooing can be a slow process. In addition to his soft grunts and visual and auditory antler communications, his urine wallows and rubs stimulate her sense of smell. Concentrated testosterone in his urine and salivary pheromones mixed with other glandular scents concoct a kind of eau de cologne that permeates the environment, enticing her with reminders of his reproductive readiness and desirability as a mate.
Large-diameter rubs on balsam fir and white birch are often made in late fall, as a bull’s urge to rid himself of his ponderous antlers increases; if you’re lucky, you may find an antler prize at the base of such a tree. Rutting rubs are made in September and October, and these smaller-diameter trees are extensively damaged, with bark removed, xylem exposed, and limbs twisted and broken. Gouges and scratches may show where the bull rubbed his antler surfaces up and down the tree and where the antler tines penetrated and scored the bark. These rubs serve as visual and olfactory bulletin boards whose chemical depositions function as breeding season announcements. Look for facial hair that has adhered to the tree where the bull rubbed his forehead and pre-orbital glands. Search also for traces of mud and neck hairs that were deposited when the bull rubbed his wallow-soaked neck and bell onto his signpost. Finally, a really fresh rub will reek of his piss de résistance.
Susan C. Morse is founder and program director of Keeping Track in Huntington, Vermont.