Their senses of smell and hearing are keen. Cow elk often bark and grunt to communicate with their calves, and calves make a sharp squealing sound. The best known elk call, however, is the bull's bugling. Bugling occurs primarily during the mating season. It consists of a low bellow that ascends to a high note, which is held until the animal runs out of breath, followed by guttural grunts.
Cows also bugle at times.
Each year, a bull grows large branching antlers that sweep up and back from the head. In May, two bumps start to swell on the animal's skull, pushing up about half an inch per day. The growing antlers are covered with a soft skin called velvet. This covering contains blood vessels which supply growth materials to the enlarging antlers. Before the autumn rutting season, the velvet dries and is shed or rubbed off.