The main purposes of a deer’s coat are camouflage and thermoregulation. Years of evolution have turned the whitetail’s coat brownish or grayish; either color blends well with a doe or buck’s natural environment. In order to regulate body temperature, a deer grows a different coat in summer and winter. This process is called molting, and it is triggered by hormonal changes brought about by the changing seasons.
No matter the season, whitetails sport a white throat patch, a white belly and white hair on the insides of their legs. They also have a 12- to 15-inch-long white tail, hence the common name whitetail. A doe typically raises and waves her tail or “flag” more than a buck does. Perhaps this is to help fawns see mama and follow her away from danger.
A fawn is born with a reddish-brown coat speckled with white spots. This allows a little deer to blend naturally with its surroundings. In the fall, after a fawn has been weaned, it sheds its spots and takes on the brown or gray coat of an adult deer.
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Summer coats are thin, helping deer cope with the heat. By September, the reddish summer pelage turns faded gray or brown. The new winter coat has hairs that are hollow, stiff and about 2 inches longer than the summer hairs. Soft inner hairs, which keep deer warm in cold weather and snow, curl against the skin.
During the rut, some bucks develop dark facial hair. Biologists say this a direct result of higher levels of testosterone in the plasma.