Whitetail timeline seen through antler changes

It's late July and in the world of whitetail bucks, a number of physiological changes are happening.

They are beginning to feed more heavily in preparation for the fall rut, their breeding season. But perhaps the most interesting change is that their budding antlers, which have been velvet-covered and growing since April, are close to fully developed.

Many people incorrectly refer to the headgear worn by whitetails as horns. Deer grow antlers, not horns. Antlers are true bone and mainly made of calcium, and are shed each winter before regrowing each spring and summer.

Antler growth on whitetail bucks originates from a plate on the skull called a pedicle. During growth, a soft, blood-rich skin called velvet covers the antlers. Antlers continue to grow throughout the summer — sometimes at a rate of an inch per day — and are fully grown by about mid-August. The antlers solidify in late August and early September, and the velvet peels off, exposing the hardened bone beneath.

However, by early June a human observer has at least an indication of the eventual size of a buck's headgear when fully mature in late summer. Beam diameter is the best hint. Also evident is the number of points a buck will have.

As a healthy buck ages, its antlers typically get larger. Usually a buck will sport its largest rack when it is about 5 or 6 years old. Beyond that, when its health declines so does the size of its rack.

Biologists believe the purpose of antlers is for social ranking, not protection from predators, because antlers are shed during winter when predators pose the greatest threat.

The process is complete when the antlers drop in winter. Antler shedding typically begins with the older bucks. Worn down from the rigors of the November rut, mature bucks sometimes shed their antlers as early as mid-December. Sometimes, a jubilant bow hunter in December is dismayed when he or she breaks loose an antler while dragging their prize from the woods.

Normally, the main antler shedding period is mid-January to mid-February. Healthy, well-fed bucks typically carry their antlers longer into the winter.

The antlers of whitetail deer differ from those of mule deer. Whitetails feature antlers that have a single main beam from which the antler tines sprout. Mule deer sport main beams that fork, and then fork again.

Occasionally, whitetail bucks grow nontypical antlers with unusual or odd tines. Sometimes, bucks sport antlers with configurations so outlandish they defy nature. An injury to the body of a buck can cause antler deformities, usually to the antler on the opposite side of the injury. This phenomenon is known as "contralateral effect."

One might think the woods and fields are littered with dropped antlers each winter, but that is not so. Antlers are a source of minerals, and sheds are soon consumed by forest creatures such as squirrels, mice and porcupines.

Bill Marchel is an outdoors writer and photographer. He lives near Brainerd. Reach him at bill@billmarchel.com.