There is something about antlers or horns on an animal that excites hunters. I guess you could say that they tell a story about the animal – their age, the dominance they possess, past injuries, the quality of their diet, and the genetics that animal has acquired from past generations. They are quite a remarkable characteristic as they grow at impeccable speeds, shed and regrow like clockwork throughout the calendar year, and take a different shape/size each consecutive year of the animal’s life. I guess some questions that we ask ourselves when studying a cervids antlers are what they are made of, what makes them grow so quickly, the timeline of their growth, and what happens when the antler is shed from the skull of the animal? In this article, we are going to explore these questions to get a better understanding of this unique feature.

What are antlers made of?

For the sake of this article, we are going to focus on antlers, not horns. Horns are different as they tend to have interior bone that is covered by an exterior keratin sheath and is usually not shed. Horns are unique to bovids, such as sheep, goats, bison, and cattle. Antlers, on the other hand, are unique to the Cervidae (deer) family and are solid structures that are extensions of the animal’s skull. Made up of bone, cartilage, fibrous tissue, skin, nerves, and blood vessels, antlers are typically found only on males cervids. An exception to this is reindeer/caribou where the females also possess antlers. These structures are shed off and grow back on an annual basis. Their main function serves as a sexual attractant to female cervids, show dominance and the degree of genetics within a herd, but also act as a combative tool when fending off predators or during physical altercations with other male counterparts.

What makes antlers grow?

Antlers are one of the many natural wonders of the animal kingdom since they are the fastest growing structures in the biological world. There are two main factors that cause antler growth to happen. The first is environmental, specifically the length of the days or photoperiod, and the second is physiological, focusing on the male hormone, testosterone. Both work in conjunction with one another in a scientific process but the general outline is as follows – as the days change in length the animal will sense this in their eyes which transfers this message through the optic nerve to the pineal gland. This is the small gland in the brain that produces a multitude of different hormones, one of them being luteinizing hormone which is responsible for testosterone production in the testes. The rise in testosterone ultimately causes the antlers to grow. As the fall season takes place the days get shorter, increasing the production of melatonin which in turn decreases the synthesis of both luteinizing hormone and testosterone. A result of the decreasing testosterone levels is the shedding of the antlers at the beginning of winter.

THE TIMELINE OF ANTLER GROWTH
As cervid species like deer, elk, and moose mature in age their antlers progress in size from season to season. This is how you can tell the general age of a buck or bull just by the size of their “rack”. The growth begins when the buck or bull is a fawn or calf. Fawns or calves only grow short "buttons", also known as pedicles, which rarely harden. As the buck matures into a yearling, these pedicles develop into its first spike or branched antlers. The size of the antlers increases annually, typically reaching their maximum size at six to eight years of age.

Antler growth typically starts in late-winter or early spring, sometimes within weeks of the shedding of their previous year’s antlers. They typically start out growing slowly, due to the length of the days, but as the days get longer the speed at which they grow gets rapid. This normally takes place by late May. By the end of the summer months the antlers are fully grown and the velvet coating that covered the structure during growth hardens and falls off, typically during the early part of September. Rubbing sites like trees and other rough surfaces are used by the bucks and bulls to scrape off the velvet to expose the hardened, polished antler as the finished product. The antlers remain in this state until they begin their shedding routine which can start mid December through to April. This all depends on the location of the animal’s habitat and the management practices in place.

ANTLER SHEDDING AND WHY IT HAPPENS
When antlers are ready to detach from the skull a thin layer of tissue, called the abscission layer, is created between the base of the antler and the pedicle. This is a result of the decrease in testosterone levels that the buck or bull is producing. The antler then loosens or is broken free as the abscission layer forms and the connective tissue degenerates. This happens quick and is the fastest deterioration of living tissue known in the animal kingdom. This may cause some discomfort for the animal so it is not uncommon that during this time the animal may rub its antlers on the ground or surrounding trees to assist with this process. If searching for antler sheds is a hobby of yours it is best to search for them along fence lines as deer are known to drop their antlers when jumping fences.

We have an understanding as to what happens within the animal for the shedding of antlers to occur however, there is not a definitive answer as to what external factors cause this, only theories. Some of these concepts include:

• Restricted diets once the weather gets colder and nutrient dense vegetation is scarce.
• Their bodies are wanting to shed damaged antlers in order to grow back new and larger ones, both for protection and dominance.
• Cold weather restricts the blood flow to the antlers.
• Energy conservation. Antlers, especially in large cervids like moose and elk, weigh a considerable amount and in colder temperatures these animals need to conserve their energy. By shedding their antlers it allows them to focus their energy on staying warm and takes “a load off their shoulders” … literally.

This information has been brought to you in thanks from Korth Group Ltd. – Outdoor Education.

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