How, When and Why Whitetail Bucks Shed Their Antlers Each Year

Tiny snowflakes floated from the sky as I slowly made my way through a thick tangle of brush. With each step, February’s wintery chill nipped at my face. Although I had no weapon, I was hunting whitetails with all of the passion I had in November.

By Charles J. Alsheimer

But on this winter day, my goal wasn’t about hanging a buck from the meat pole. It was about finding shed antlers.

aAntlerDog

Hunting shed antlers with a trained dog, or even with your ol’ buddy who isn’t trained but loves you to death, is a good way to enjoy the woods after deer season has ended. (Photo: Charles J. Alsheimer)

Just as I stepped from behind a snow-covered hemlock sapling, a deer jumped from its bed and bounded from sight. Unable to get a good look at it, I decided to check out its bed to see if I could determine if it was a buck or doe. Upon reaching the bed, I was treated to a sight all shed hunters dream of finding. There were several small drops of blood on the fringe of the bed’s snowy depression. Inches away lay a freshly cast four-point antler. As I bent down to pick the antler out of the snow, my eyes were drawn to the antler’s pink, bloody burr.

Thinking the buck might have cast his other antler when he jumped from his bed and ran, I decided to follow. After following the buck’s tracks for several hundred yards and finding no sign of the other antler, I gave up the pursuit. For the next few minutes, I paused to closely examine the shed. As I gripped the antler at its base and ran my fingers over the long tines, I couldn’t help thinking about how the buck had grown the antler. I also thought about how and why it had been shed on this day.

Why and How it Happens
If you’ve taken a close look at a boiled deer skull, or one that has lain in the woods for some time, you might notice a faint line just below the antler burr. This line is a unique layer of cells called osteoclasts, and where the antler will separate from the skull when casting occurs.

Antler casting takes place when a buck’s testosterone level decreases. Next, the osteoclast layer of cells begin to absorb calcium from the antlers, causing the bone to weaken and become grainy and chambered. When this happens, little more than a light tap or the weight of the antler is all it takes for the antler to fall off the buck’s head. The rough, porous bottom of the antler vividly shows what occurred when the osteoclast layer of bone broke down.

In most cases, the cast antler has a convex base with a depth anywhere from ⅛ to ½ inch. This leaves a corresponding crater in the pedicule layer of bone. After the antler is cast, the exposed bone bleeds, causing a scab to form. The scab then heals from the outside of the pedicule to the center. When fully healed, the top of the pedicule is covered with a brownish-gray skin, with a small light-gray dot in the center of the pedicule.

Many people often ask whether bucks feel pain when casting takes place and how fast it occurs. Many assume that bucks feel pain when their antlers are shed. This is likely not the case. In one study,  researchers discovered that whitetails, when under extreme stress, produce naturally high levels of B-endorphin (especially in fall), which supports a high pain threshold and rapid wound healing.

Endorphins consist of morphine-like chemicals from the pituitary gland, allowing the animal to control pain. In addition, bucks experience rapid buildups of steroids and androgens in the bloodstream. This promotes healing, helps manage stress, and suppresses and prevents inflammation.

After closely observing the casting process during the past 20 years, I believe bucks feel no pain when they cast their antlers. What I have observed is that bucks are startled and curious when their antlers drop from their heads. A buck might lunge away from the cast antler as it hits the ground, and then cautiously come back to examine it. In some cases, I’ve even seen the buck lick his shed antler.

The speed at which casting occurs is very interesting. For starters, the breakdown and granulation of the osteoclast layer of cells occurs rapidly. For example, I’ve been able to grab one of our pen-raised buck’s antlers one day, finding it firmly attached to the buck’s head. Then, less than 48 hours later, I’ve discovered the buck has cast one or both of his antlers. This rapid antler breakdown and casting has been documented numerous times with pen-raised deer.

Of the many bucks I’ve raised, only two have dropped both antlers at the same time. In all other cases, the second antler was cast 12 hours to four weeks later. On average, most bucks have carried the second antler four days to seven days after casting the first antler, which illustrates why it is so difficult to find a matched set of sheds.

When it Happens
Decreasing day length, decreased testosterone levels, health and genetics are critical components in determining when a buck will cast his antlers.

A buck’s testosterone level peaks around Nov. 1 in the North. When the rut is over and the shortest days of the year arrive in December, testosterone levels begin to plummet, setting the stage for the antler-shedding process. At this point, the buck’s health and genetics play a role in determining when casting happens. If a buck is stressed from inadequate nutrition, the rigors of the rut or an injury, he will drop his antlers earlier than if he wasn’t stressed.

We’ve probably heard of cases where hunters have killed bucks in December only to find that the buck has already cast his antlers. Follow-up usually shows that the buck was wounded, stressed from breeding or nutritionally deprived.

Most Northern bucks shed their antlers in January or February. Generally, mature bucks and bucks stressed from the rut will cast their antlers first. Of the bucks I’ve raised, most cast their antlers from Jan. 20 to March 10. The earliest I had a buck cast antlers was Jan. 1 (he was injured), and the latest was April 3. One of the things I’ve discovered from raising deer is that if a buck is in prime physical condition and stress-free, he will cast his antlers within the same three- to four-day period each year between ages 4 and 8.

One buck I raised always cast his antlers within a day or two of Feb. 25 each year between ages 4 and 8. When he was 9, his casting occured earlier each year until he died at 12.

Attitude Adjustment?
When a buck casts his antlers, his testicles are still functioning, hormones are still in his system and his pituitary is not affected, so you might think his attitude would be the same as when he had antlers. Not so.

Research has shown that most bucks become less aggressive and quite mild after antler casting occurs. It’s not known why this is, but most biologists and deer breeders I’ve talked with believe the drop in testosterone levels, the buck’s weakened state, and the fact that the buck realizes he no longer has antlers make the animal become less aggressive.

Are Antlers Needed to Breed?
Although rare, research has shown that a buck will attempt to breed a doe after he has cast his antlers.

In 1997, I witnessed this firsthand when one of my enclosure does entered estrous and was bred every month from November through March. Each time she was bred from November through February, a mature, antlered buck did the breeding.

However, when she cycled again in March, most of the bucks had cast their antlers, so it was interesting to see bald bucks exhibit various rutting behaviors toward each other and the doe.

Eventually, one of the antlerless bucks bred the doe. And, for unknown reasons, the doe never conceived fawns that year.

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