Antlers are a trademark characteristic of the deer family cervidae, which includes caribou, elk, moose, mule deer and white-tailed deer. The antlers' appearance has no measurable physical effect on the deer; rather, it is believed to be an evolutionary adaptation that allows the male of the species to attract females, defend itself, establish dominance and compete for mating rights.
Deer antlers are among the fastest-growing tissue in the animal kingdom, growing as much as 1/2 inch per day during periods of peak growth. Male deer begin to grow antlers at about 4 to 6 months of age; however, since bone growth always takes precedence over antler development, large antlers are seen only on the most mature deer. Antlers grow and are shed annually in a predictable cycle that begins when the days become longer in late spring and ends in the fall, corresponding with mating season. This cycle seems to support the theory that antlers are mainly a means for mature males to compete with each other for mating rights.
Early in their development, antlers have a robust blood supply and are covered with soft, downy hair called velvet. Antlers at this stage consist primarily of cartilage and blood vessels and a small amount of minerals. As the antlers mature, they lose their blood supply and become mineralized and hard. In winter, the antlers become loose and eventually fall off.