Shed Antlers: Did You Know?

shedpupEditor’s note: If you’re a whitetail nut, you’re probably thinking about shed hunting right now. Here are some incredible shed antler insights from the inimitable Charlie Alsheimer’s writings in Deer & Deer Hunting.

One of the most incredible things about whitetails is their ability grow a new set of antlers each year and then cast them a few months later. Why, how and when a whitetail buck casts its antlers is one of the most fascinating phenomena in nature.

Why it Happens

Antler casting is driven by five things: shorter day length (photoperiodism), decreasing levels of the hormone testosterone, the buck’s physical condition, available nutrition and genetics.

Photoperiodism and testosterone: Shorter day length is one of the main drivers in determining when a buck will cast its antlers. After the rut is finished, day length is the shortest of the year, especially north of the 35th latitude (from North Carolina to Missouri and points westward). With this drop-off in daylight comes a decrease in a buck’s testosterone level, which sets the stage for antler casting to occur. Though shorter day length and drop in testosterone levels are critical markers in the antler casting process, they are not the only factors that determine when it will take place.

Throughout most of the whitetail’s range, antler casting occurs from December through April. The reason it spans nearly five months is determined by stress, nutrition and genetics.

Stress: Of all the stressors bucks encounter, an injury is often the biggest contributor to an earlier-than-normal antler cast. I’ve witnessed the impact stress has on antler casting dates of individual bucks in Texas, New York and Pennsylvania.

I once raised a buck that lived to be 11. When he reached 3½, he cast his antlers the first week in March each year, except one. The exception took place when he was 6. While in a fight during the rut, he incurred a nasty puncture wound in his left hindquarter. The wound swelled and became infected before finally draining in mid-December. Though the buck overcame the injury and infection that followed, the stress to his body caused him to cast his antlers less than 100 yards apart on Christmas day — more than two months ahead of schedule. He eventually healed and regained his strength so well you would never know he had been injured. The next year he was healthy and injury-free, and cast his antlers right on schedule within hours of each other the first week in March.

Wounds from fighting aren’t the only stressors that can play a role in earlier than normal antler casting. Too many deer, predators, wounds from arrows and bullets, snowy and cold conditions and lack of adequate food are other stressors whitetails encounter that contribute to their overall well-being.

Nutrition: When the rut ends, a whitetail buck’s physical condition can be ravaged, especially in areas with few adult bucks and high doe populations. As a result, it’s not uncommon for a buck’s post-rut weight to be 20 percent less than when the rut began. It is critical for bucks to have adequate food sources to allow them to recover from the rut. Without good health it is difficult to see the role genetics plays in the antler casting process. This is particularly the case in wild-free-ranging deer, where food quality varies from year to year. When food quality is poor antler casting will almost always come early in winter. The bottom line is if a buck’s health is compromised by lack of food, injuries, too many deer or the other factors I’ve mentioned, it’s unlikely to see them carrying their antlers into February.

Genetics: Much of what I’ve learned about antler casting has come from raising whitetails. Every buck I’ve raised had an obvious biological clock that set the time of its antler cast each year. When bucks reached 3½ years of age (when skeletal frame is fully developed) they cast their antlers in the same five- to 10-day period until age 8, providing they were healthy coming out of the rut. In all cases, after they reached 9, their antler casting dates were anywhere from two to four weeks earlier than when in their prime.

 How it Happens

Because all bucks are different, each has its individual testosterone base point that must be reached before casting can occur. When it happens a layer of cells called osteoclasts (situated 1/16 to 3/8 inch below the antler burr) begins to reabsorb calcium. When this layer of bone fully deteriorates, the antler’s weight will cause it to fall off the buck’s head.

Little is known about how fast this process occurs. However, it happens very fast. I’ve actually grabbed one of our research buck’s antlers (about the time I knew they were ready to cast) and found it firmly attached and rock solid, and the next day or two, one or more of the buck’s antlers had been cast.

In the seconds after the antler is cast, the exposed layer of pedicle bone and bottom of the cast antler are slightly bloody (this is because all healthy bone has blood in it). Within minutes, a thicker layer of blood will flow from the small crater left in the skull when the antler was cast. The blood takes about six to 10 hours to fully dry, forming a scab. Also, the bottom of the cast antler will smell of decay for an hour or two after casting occurs.

A buck rarely casts both of its antlers at the same time. In most cases, when the first antler drops, the second will fall anytime from minutes to a week or more. In more than 20 years of raising whitetails, I’ve only had three bucks cast both antlers at the same time, and none of the three ever did it again. The longest period I’ve witnessed between the first and second antler casting was 41 days. This was far from the norm and the only time I’ve seen more than three weeks between casting dates.

People often ask me if a buck feels pain when the casting occurs. Based on what I’ve observed, I’d have to say no. Nor does the exposed bone seem to cause bucks discomfort in severe cold. However, they do not like the smell of their own blood and tend to shy away or run from their dropped shed.

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