A Brief Primer on Antler Biology - The Annual Antler Growth Cycle and Factors that Matter in Antler Growth

One of the qualities that makes the members of the deer family, Cervidae, so unique to the animal kingdom is their antlers. Cervidae, which includes species from around the world such as caribou, deer, moose and elk, is made up of a wide diversity of hooved animals (ungulates) that grow antlers. Antlers differ from horns in that they are made of bone tissue and are shed every year. Horns are made of keratin, are not shed annually, and continue to grow for years. Whether or not you care about antler size as a hunter, understanding the biology behind antler growth can help you assess the health and age structure of the population you hunt.

Bull elk in velvet, early summer, Colorado. M.P. Photo. 

The best-supported answer to the question “Why do deer grow antlers?” is that antlers are used to fight other males during the breeding season, as well as signal health and quality of male deer to other males as well as females. If cornered, antlers may be used as a defense against predators, but the go-to response of most deer is to flee. Older deer generally have a larger body size and bigger antlers, and procure dominance during the breeding season. Year-to-year, there is a larger change in antler size during the first few years of a deer’s life, and the growth curve flattens out around age 6. During a buck’s first year of life, he may grow small velvet-covered “buttons”, but this is mostly dependent upon nutrition as a fawn and varies by population.

The Annual Antler Growth Cycle

Post-Rut

After the breeding season, anytime from January through April for white-tailed deer, the cells that form the connection between the antler and the pedicle begin to cause weakening along the abscission line. Once these cellular changes take place, antlers drop, leaving an open wound on the pedicle. Some antlers will be dropped almost simultaneously while other deer may carry around a single antler for a longer period of time. It takes a few days for the pedicle to heal back over.

Shed mule deer antler showing where osteoclasts weakened connection between pedicle and antler along abscission line. M.P. Photo. 

Early spring

In April and May, antler growth slowly begins a few weeks after the previous year’s antler was shed. Unlike horns, antlers grow from the tip. Inner “spongy bone” has a high amount of blood flow, which brings nutrients and hormones to the antler. The antler is covered in small, oily hairs that stick straight out and give the growing antler the appearance of velvet.

Buck with velvet antlers in early summer, Colorado. M.P. Photo. 

Summer

The most rapid antler growth takes place in the early summer months, when forage quality is high and nutrients are readily available to support growth. The outer portion of the antler is mineralized into compact bone. In areas with high quality forage, older bucks’ antlers can grow at a rate of 1.5 inches per week. Antler growth is energetically costly, and during this period of rapid growth is considered one of the fastest growing tissues in the animal kingdom. Calcium and phosphate are actually mobilized from skeletal bones in the deer’s body to contribute to antler formation.

Early fall

Once antler growth is complete, the “velvet” on the outside of the antlers dries up and is rubbed off on vegetation. The antlers can appear bloody and shiny, and are fully formed at this point to send a message during the upcoming fall breeding season.

Dead-head elk illustrating separation between skull and antlers, Wyoming. M.P. Photo.  

Factors that Matter in Antler Growth

Antler growth is controlled by a hormonal cycle influenced by seasonality. Supporting this are the three main factors that can influence antler growth: nutrients, genetics and age. Older bucks will have larger antlers, but one of the most important factors for antler growth is the quality of maternal care in young male fawns. If habitat and forage is good for a doe to take excellent care of her fawns, healthy buck fawns will have the resources to put into antler growth later on. When it comes to macronutrients, a high protein diet contributes to antler growth. Micronutrients such as calcium and phosphate are also necessary to support antler growth and the skeletal bones that also play into the growth cycle. Because of the wide variety of soil nutrients geographically, the outcomes of nutrients available in the environment can be seen at the population level. Relatively little is known about paternal genetics and antler growth, but a healthy mother and subsequent maternal care matters.

Abnormalities in antlers can be caused by a whole host of different things, often including injuries to the velvet antler or pedicle, or injuries to the buck’s legs or testicles. Testicular injury can cause hormonal imbalances that result in some highly abnormal antlers. Bucks with low testosterone often stay in velvet well past the time they would normally have lost their velvet. Disease such as brain abscess and certain viruses can also result in unique antlers.

Antlers are a unique natural phenomenon that can be considered an outward expression of an animal’s health and vitality. Whether or not you are interested in “trophy management”, having a working knowledge of antler biology can add a whole new level to assessing the animals you’re seeing in the woods and even managing habitat and harvest to improve population-wide antler quality!

Foundry Outdoors is your trusted home for buying archery, camping, fishing, hunting, shooting sports, and outdoor gear online.

We offer cheap ammo and bulk ammo deals on the most popular ammo calibers. We have a variety of deals on Rifle Ammo, Handgun Ammo, Shotgun Ammo & Rimfire Ammo, as well as ammo for target practice, plinking, hunting, or shooting competitions. Our website lists special deals on 9mm Ammo, 10mm Ammo, 45-70 Ammo, 6.5 Creedmoor ammo, 300 Blackout Ammo, 10mm Ammo, 5.56 Ammo, Underwood Ammo, Buffalo Bore Ammo and more special deals on bulk ammo.

We offer a 100% Authenticity Guarantee on all products sold on our website. Please email us if you have questions about any of our product listings.