Q: Why do deer shed their antlers each year?
A: 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 a 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.
Q: Why does the fur coat of a deer change colors depending on the time of year – a reddish color in the spring and brown in the fall?
A: A deer’s coat is designed to provide both a means for thermoregulation and camouflage. Summer coats appear reddish and are thin, allowing deer to better cope with heat stress. In the fall, deer begin a process of molting, which is triggered by hormonal changes that reflect the changing seasons. The reddish summer coat turns into a faded gray or brown color as the new winter coat begins to grow.
The winter coat is comprised of two layers. Outer guard hairs are hollow, stiff and grow about 2 inches longer than the undercoat. The inner layer is soft and dense, which insulates deer from the cold weather and snow. Coat color, regardless of the season, tends to be darker in forested areas and lighter in agricultural areas where deer are exposed to more direct sunlight.
– Michelle Carstensen, wildlife health program supervisor