Male whitetail deer are called bucks and they grow antlers during the summer. The antler is a honeycomb, bone-like tissue they use to fight other bucks and also to “rub” trees to mark their territory. While the antlers grow, they are covered in a velvet-like texture; however, high levels of testosterone during "rutting" (mating) season cause the velvet encasing to die off and bucks will also rub trees to help remove it. A drop in testosterone, after the rut, causes weakness in the connection tissue and the antlers fall off.
Antlers drop annually in late winter, typically January through March. The dropped antlers are called “sheds” and the process does not hurt the buck. From spring through summer, the antlers grow back and are usually bigger than the previous year. From August through September, the antlers lose the velvet encasement in preparation for the whitetail breeding season. The breeding season is know as "rutting" and it occurs from October to early December. The cycle then repeats.