So why do deer shed their antlers each year? Annual cycles in deer antlers are related to the changing seasons. Deer have adapted their physiology and behavior to respond to seasonal changes, including antler growth and shedding. The environmental cue that regulates antler growth is the amount of day length; the physiological cue is the hormone testosterone.
Simply put, the changing day lengths are sensed by the eyes, which send this message through the optic nerve to the pineal gland located at the base of the brain. The declining day length in late fall and early winter causes a decrease in testosterone, which results in antler shedding.
The actual process of antler shedding involves ta thin layer of tissue destruction that forms between the antler and the pedicle, called the abscission layer. The degeneration of the bone-to-bone bond between the antler and the pedicle is considered to be the fastest deterioration of living tissue known in the animal kingdom. Michelle Carstensen, DNR wildlife health program supervisor.