Why Do Deer Shed Their Antlers?

Every year, bucks lose their antlers and grow a brand new set. Deer do not have to try to shed their antlers – the antlers shed themselves as part of a natural process that corresponds to the reproductive cycle. Maybe you’ve noticed that deer antlers look different depending on the season, or you’ve stumbled across a set of antlers in the woods and wondered why they’re there with no bones present. In this guide we’ll explore why deer shed their antlers, when the shedding season happens, and how the process works from beginning to end.

Why Do Deer Shed Their Antlers?

The process of the pedicle weakening and the antlers falling off can occur quite rapidly. Even if a deer’s antlers are secure on the head one day, they may end up falling off within 1 – 2 days. In general, a young and very healthy buck will keep his antlers longer than an older or weaker one.

But why did deer evolve this cycle at all? The primary reason male deer have antlers is to make them more attractive to female deer during the mating season. Bucks display their fully grown antlers to females and use them to establish themselves as dominant males, fighting one another for dominance and mating access.

Deer also use their antlers to defend themselves against predators as well as other deer. When two males confront each other, they strike one another with their antlers, which sometimes lock together. In extremely unfortunate circumstances the antlers become so strongly locked that the deer cannot disentangle themselves and die from starvation.

Antlers are greatly damaged over the course of the mating season by the stressors of fighting and other sources of wear and tear. Points may become blunted or even break off entirely by the end of that time of year. Shedding the antlers every season gives the deer the chance to grow a new set that is stronger and more useful for the next rut.

Some female deer do have antlers, but this is only the case with Reindeer, who need their antlers to dig for food in the snow.

Why Do Deer Have Antlers Instead of Horns?

If you compare horns to antlers you’ll find that, unlike antlers, horns are unbranched and permanent – they never fall off or get replaced. A horn has a core of bone enveloped by a sheath of keratin, and in certain horned animals the horn continues to grow throughout the animal’s lifetime. Horns are grown by animals in the bovine family, such as goats, and often by both males and females.

Horns are primarily used for protection, though they can also be used for sparring between males. This contrasts with antlers, which are used to attract mates and ward off competition during the rutting period. Antler shedding is also not the same as “horning” – the removal of a horn from a horned animal – which is often painful because horns are meant to last a lifetime, whereas antlers are only meant to last for the season.

That said, humans use horns and antlers for similar purposes: as decorations or wall mounts, or carved into furniture and other useful objects.

When Do Deer Shed Their Antlers?

Bucks will lose their antlers as early as January to as late as April. The exact timing depends on the age of the animal, as well as the latitude of its habitat, at the point after the rut has concluded. Antler shedding is also referred to as the “drop,” and it takes between two and three weeks from when the shedding process kicks in for the antlers to actually fall off.

A buck’s testosterone level usually starts increasing in July and reaches its highest point between late October and early November, during the breeding season. Once the rut is over, testosterone falls and stays low from the end of December until July. Bucks need a high testosterone level to keep their antlers in place, which is why the drop follows the rut.

What Factors Determine When a Deer Sheds Its Antlers?

Five primary factors determine when an individual buck will shed his antlers:

• Hormones – A buck’s testosterone level is the most important factor in antler shedding and growth. Testosterone falls at the end of the breeding season, and that’s when the shedding process starts. The return of testosterone in summer allows the antlers to grow again.
• Photoperiodism – Changes in day length drive the hormonal cycle. Testosterone increases as days shorten, when antlers develop, mineralize, and eventually lose their velvet. As daylight increases toward spring, testosterone declines and the antlers drop.
• Physical injuries – Injuries from fighting, hunting incidents (such as a shot that hits the antlers), or car collisions can weaken the animal and compromise hormone production, leading to early shedding, weakened antlers, or impeded regrowth.
• Malnourishment and other stress – Antlers need proper nutrition like every other part of a deer’s body. A malnourished or starving buck will probably shed earlier than it would otherwise. Bucks often neglect feeding during the rut, so it can be tricky to tell how much early shedding is due to normal hormonal changes versus malnutrition – often it’s a mixture of the two.
• Living near other bucks – A buck living in a herd with several other bucks will probably maintain higher testosterone for longer, leading to more intense mineralization of the pedicle and antlers that shed later in the year.

Disease can also disrupt the antler cycle. Malnourishment makes an animal more susceptible to disease, and certain parasites may create issues with antlers too. Because growing antlers takes even more energy than maintaining them, a buck in poor body condition may shed early and regrow its antlers late or abnormally.

How Do Deer Shed Their Antlers?

Deer grow a new set of antlers every year. When that living tissue hardens for combat during the rut, blood flow to the antlers ceases and the antler is no longer a living part of the deer’s body. After the mating season, the drastic decline in testosterone causes bone cells called osteoclasts to reabsorb calcium between the pedicle and the attached antler, dissolving the connecting bone tissue until the antler falls off. Many deer accelerate the process by rubbing their antlers on branches and trees.

Antlers are an extension of the deer’s skull, made of calcium and phosphorus. They are true bone – some of the fastest-growing bone on the planet – with a texture somewhat like honeycomb. The pedicles are the points on the deer’s head from which the antlers grow, and when the antlers are shed, they fall from the pedicles.

A male deer’s pedicles develop during the first year of its life. During the second year, small shafts develop, and it is in the third year that the first branch may be seen. Older deer often have thicker and longer antlers than younger ones.

Bucks sometimes shed their antlers at different times. A buck may drop one antler and carry a single antler for two or three days before losing the other, which is why it’s possible to see a one-antlered buck in the wild.

Is It Painful for Deer to Shed Antlers?

No, it does not hurt when deer shed their antlers. By the time deer are shedding, blood flow between the antlers and the rest of the body has stopped, and the antlers are essentially separate from the skull. Of course, we can’t ask deer how they feel, so there is no way to know for certain – but they do seem to experience some discomfort when shedding the velvet from their antlers.

There can be some blood when the antlers are fully shed, but bleeding is more common during velvet shedding, when the antlers still have blood flow. The bleeding velvet gets itchy, which is why deer rub their heads against trees to get rid of it.

The Antler Growth Phase

While the antlers are regrowing each year, they have a covering of “velvet,” a soft membrane layer of skin that provides the required nutrients to the developing antlers as they build bone mass. The rapid blood flow from the head through the antler gives growing antlers their fuzzy, velvety look.

The velvet is rich in many different substances, including proteins, minerals, amino acids, and Growth-Factor 1, a protein hormone with a molecular structure similar to insulin.

The growth phase takes about 2 to 4 months for most species of deer. Antlers contain large amounts of protein and water as they develop, eventually ossifying to become completely bone-like – a change driven by both the environment and the animal’s hormones. Growth slows during the summer as testosterone rises, constricting the arteries and veins around the velvet and impeding the supply of blood and nutrients.

Around early September the velvet dries up and falls off, helped along as the deer rubs its antlers against trees in a process called velvet shedding. This leaves bucks with hard antlers to use for ritualized contests during the mating season.

Do All Deer Shed Their Antlers?

No, not all deer shed antlers, but all deer that have antlers shed them. In most species only male deer have antlers, so in most cases female deer do not shed antlers because they do not have them. The exception, again, is the Reindeer – the only species of deer in which females have antlers.

Most male deer only develop antlers when they are fully grown, so baby deer do not shed them. In some species, such as the Red Deer, the antlers grow in size every year, meaning a younger deer will have shorter antlers than a more mature one.

What Happens to Deer Antlers When They Fall Off?

Like all biological matter, shed antlers eventually decompose, providing nutrients for the soil that in turn provides food for the deer again. Some animals eat fallen antlers since they are an excellent source of nutrition – some deer species, such as moose, will even eat their own antlers once they have been shed. Shedding is good for the ecosystem, feeding smaller animals and enriching the ground.

When Should You Look for Shed Deer Antlers?

If you want to find shed deer antlers, it’s best to look just after the snow melts at the end of winter. In regions with deep snow you may have to wait until then; where there is less snow you can look a bit earlier, though you may not find as many. If deer live in your area, you will often find shed antlers lying around even with a bit of snow still on the ground.

Deer often leave their shed antlers in their bedding areas. Deer bedding areas are mostly in spots with heavy cover, away from where humans tend to walk, and often near food sources – deer want consistent access to food while minimizing travel time, because the more time they spend traveling, the more visible they are to predators, including humans.

When Do Deer Have Their Largest Antlers?

Most male white-tailed deer have the largest antlers of their lives between five and seven years old. Deer living in a difficult environment – poor nutrition, for example – may reach their maximum antler size later rather than sooner.

You’re most likely to find the largest shed antlers where deer enjoy consistent access to a balanced diet in every season. Regrowing antlers especially requires calcium to be redeposited into bone, so areas with excellent deer nutrition tend to produce larger sheds.

Final Thoughts on Deer Antler Shedding

Antler shedding is a natural annual process that every antlered deer undergoes. It may look painful, but it does not harm the deer – it’s an essential part of the reproductive cycle. Bucks shed their antlers after the rut when testosterone falls; the timing runs from January to April and is influenced by injury, nutrition, day length, and herd dynamics; and the antlers detach when osteoclasts dissolve the bone connection at the pedicle. If you understand when and how the process occurs, you have the knowledge needed to be an effective shed antler hunter – look at the end of winter, near bedding areas and food sources.