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Avoid Ground Shrinkage with This Simple Formula

by Dr. Grant Woods   |  June 29th, 2016 0

By mid-July, many whitetail hunters are sharing trail-camera pictures of bucks with large antlers covered in velvet.

Folks will be trying to estimate the score of these bucks and guess how many more inches they will grow. This article will help you do just that.


Dr. Grant Woods poses with Clean 12 in October 2011 after getting many trail-camera photos of the same buck earlier in the year.

Even though bucks only have velvet antlers for about four months, the antler-growing process occurs year round. As part of this process, bucks seek a protein-rich diet during the growing season and minerals throughout the year.

Protein is the primary ingredient of growing antlers. Bucks consuming a protein-rich diet tend to produce larger antlers for each age class compared to those living in habitat where protein is limited. This is obvious by comparing the average antler size per age class of bucks from the Midwest, where soybeans are commonly grown, or South Texas, where many of the native plants are rich in protein, to areas dominated by grass or timber.

Around mid-July, bucks slow down transporting protein to the developing antlers through blood flow and begin transporting calcium. Velvet antlers are full of blood vessels. This extremely high blood flow is necessary to transport enough calcium and other minerals to the antlers to basically fill the developing antlers with these minerals.

The mineralization of antlers takes about a month. During this stage of development, antlers are still covered with velvet but don’t grow very much. Therefore, bucks won’t score much more in October than they do in late July. Except for being covered with velvet, accurate estimates of antler score for an individual buck can be made during late July.

Scoring Velvet Bucks
Deer season opens in some areas early enough (South Florida, the coastal counties of South Carolina, and Kentucky) that all or a majority of bucks have velvet antlers. In fact, many hunters travel to these states during the early season for the primary purpose of tagging a “velvet buck.” These are unique trophies considering that archery season doesn’t open in most states until a majority of bucks have shed their antler velvet.

“This ground shrinkage was a result of estimating his score based on velvet antlers, and that experience confirmed that velvet does indeed add about 20 percent to what a buck’s hard antlers will score.”

Accurate estimates of score are useful for comparison purposes. Fortunately, enough racks have been scored with the velvet on and then after the velvet has been removed to provide an idea of how much velvet adds to the score. Data from scoring the same bucks with and without velvet indicate that, on
average, velvet adds about 20 percent to a buck’s antler score.

For example, a buck that scores 150 inches with velvet on will score about 120 inches with the velvet removed. Add to this the excitement of looking at trail-camera pictures before the season and it’s easy to see why many bucks experience “ground shrinkage.” Ground shrinkage is a term used to describe the difference in perceived antler size before and after harvest.

I’ve been a victim of ground shrinkage myself! During July and August 2011, I was getting pictures of a 12-point buck my friends and I estimated would score in the high 140s. That’s a huge buck in the county where I live. Stone County has extremely poor soils and the primary land use is mismanaged oaks and hickories and fescue pasture. As far as I know, there’s not a single production soybean field in the county.


Back in 2011, Dr. Grant Woods got numerous trail-camera photos of a buck he named “Clean 12.” Woods estimated the buck’s antlers would score in the 140s, but when he tagged the buck in October he realized the buck only sported a 120-class rack.

I began planning a strategy to tag the buck I called “Clean 12.” A cold front was forecast to pass Oct. 21. So, I selected a stand close to where I thought Clean 12 was bedding. Sure enough, I spotted Clean 12 passing about 70 yards away through the timber. The short story is that Clean 12 responded aggressively to some grunt calls and presented me with a three-yard shot. (You can watch the hunt online at

The Formula
I was (and still am) thrilled that my strategy worked to tag Clean 12. But I admit I was shocked when I put my hands on Clean 12 and realized he was a 120-class buck; not the 140-plus I was expecting. This ground shrinkage was a result of estimating his score based on velvet antlers, and that experience confirmed that velvet does indeed add about 20 percent to what a buck’s hard antlers will score.

If you want to estimate a buck’s antler score based on pictures when his antlers are covered with velvet, remember to reduce the guess by 20 percent. This formula is good preventive medicine for ground shrinkage!

I hope each of you enjoys some successful hunts and fresh venison this fall. If you are blessed enough to get some trail-camera pictures of a good buck this July, use this information and you’ll have a good idea of what he’ll score when you put your tag on him in a few months.


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