Of all its senses, the sense of smell is the most acute. The deer evolved as a woodlands animal that had to use its nose to communicate with as well as locate and identify other deer. This was because the dense habitat restricted visual communication. During the hunting season, bucks are constantly testing the slightest air currents and pinpointing hunters. Most hunters know that deer have glands that enable them to communicate by scent even when they are unable to see one another.
Deer depend on their sense of smell to avoid predators, including man.
Studies have shown that in relatively open country in a gentle wind, deer can detect the odor of man for distances of up to half-a mile. In short, the buck's sense of smell plays a major role in daily communication with other deer, sexual activity, food location and selection, danger warnings, and selection of travel routes. So the animal is always on the alert and constantly testing air currents. Too many hunters think putting on some commercial cover scent is all they have to do to be protected from the buck's sense of smell. Far from it.