Hunters have long been intrigued by variation in the color of deer antlers. Archibald Rutledge’s writings immortalized the dark racks of South Carolina’s lowland swamp bucks as unique and special. Others have admired the glistening appearance of exceptionally white racks. For years, the color differences in the racks that line my walls have left me puzzled. Some are white, some ash, some brownish grey, some amber, others colored like bourbon, and others still darker than chocolate with a sheen of their own.
I’ve heard hunters propose causes for this variation that are as diverse as the range of colors. They include genetics, mineral intake, nutrition, sun exposure (or lack of it), buck age, exceptional acorn production, blood content in the velvet at time of shedding, and chemicals in the sap of trees the buck rubbed – among others. Which if any of these theories is correct? I decided to do more than just ponder the mystery.
Likely Theories
The stark whiteness of old shed antlers argues that sunlight has the potential to bleach, especially when contrasted to the sheds I find deep in the swamps of my home state of Florida. Could the tannic acid in acorns affect antlers? Admittedly, this seems far-fetched considering that, in most areas, antlers grow and harden before acorns become widely available. While a buck’s age may not directly cause antler darkening, it affects rubbing behaviors; mature bucks rub more trees than younger bucks, and that could certainly affect antler color. At the time of velvet shedding, hunters witness racks ranging from bright red to deep rust to flamboyant pink. Do these form an initial stain to the racks that influences the final color?
Two findings deserve especial consideration. First, the colored layer – whether amber, root-beer, or even darker – is shallow. It is limited to the extreme exterior of an antler, as a light scratch with a pin or knife point will verify. In fact, anyone who has fashioned a knife handle, buttons, checker pieces, or pegs from antler can testify to the light, creamy color of the antler’s interior. Secondly, the exposed surfaces of broken tines quickly assume the shade of the surrounding antler. Because of these facts, it seemed obvious to me that chemicals from rubbing, especially from sappy trees like pines, are primarily responsible for the color of the rack. But I wasn’t satisfied yet. I needed to test my theory with a few experiments.
A Unique Nebraska Buck
This past November, while hunting in Nebraska, I was amazed by the bold whiteness of the whitetail racks that rendered distant bucks blazingly visible. I arrowed a buck with massive main beams and tines. When a young man from the area gave me a shed dropped by my buck two years before, I recognized it, having photographed the buck at less than 10 yards (seen above) on the last morning of my hunt that year. Since then, I have often looked at the photos and wondered why I hadn’t arrowed him. Seeing the monstrous rack from 2023 made me thankful. While comparing my photos to the shed, I noticed a defined white spot on the right antler. This eliminated any doubt to the deer’s identity, but it also heightened my curiosity as to why this area remained lighter than the rack as a whole. Furthermore, the rack two years later displayed light spots in the same areas (photo below). Why? Could this shed light on the mystery of antler color?
The shed antler from 2021 is positioned below the rack to show similarities in the positioning of the whiter areas. Also note the dull, rusty color is restricted to the knurled portion of the bases where material from rubbing could collect despite the antlers’ hardness.
The fact that two antler cycles later the same regions remained lighter than the rest of the antler suggested to me a retained condition in antler development. Somehow a portion of the antler was more resistant to staining. Could the reason be greater mineralization in those areas or some sort of repellent incorporated into the surface? Testing the hardness could furnish the answer.
Citizen Science for Deer Antlers
I ordered a durometer – a gauge for measuring the hardness of materials – only to discover the hardness of antlers exceeded the durometer’s capability to register differences. Sharpening the durometer’s point did help, but the values measured were not consistently repeatable. Better testers are available, but my curiosity did not justify a $3,000 expenditure, so next I tried an assortment of files that rate the hardness of steel products.
Again, I was disappointed. Even the softest file scored all the antlers. However, I discovered that, dragged backward, only the harder files left visible traces. Obviously, the results wouldn’t equate to the hardness values marked on the files, but the differences in antlers or portions of antler could be brought to light. Sure enough, the lighter areas of my buck’s rack required a file two levels harder to score in that manner than the bulk of the antler. On the other hand, my dark Florida racks scored even with the lightest file, suggesting much softer mineralization.
A Look Inside Antlers
I next considered radiographs, which can reveal comparative densities. For instance, the enamel portion of teeth shows up whiter on an x-ray than the less-calcified dentin layer which in turn is lighter than the non-calcified pulp. For bones, the denser cortical layer is whiter on a radiograph than the spongier inner core. Increased mineralization equates to less penetration by x-rays and, therefore, a whiter appearance on the film. Metals, blocking all passage of the rays, cast a completely white shadow. Could x-rays demonstrate a difference in antler mineralization?
My dentist was happy to help. Because increased thickness of antler would affect the result as much as increased mineralization, a tape measurer was employed to mark tines at levels of the same circumference on a whitish rack, a dark rack, and one slightly darker yet. To identify them on the radiographs I used melted candle wax to attach small screws. The lightest rack’s tine received one screw, the darkish one, two screws, and the darkest, three screws.
The x-ray gave strong proof that the light-colored tine (marked with one screw) was the most dense. Differences in the density between the other two tines was not as obvious, indicating the slightly increased darkness of one was likely more attributable to trees selected for rubbing.
Deer antlers consist primarily of 11 different minerals, with calcium (19%) and phosphorus (10%) being most important, but they are not distributed evenly throughout. Since antlers are more porous and, thereby, less mineralized in their central cores, all three radiographs presented a broad, midline shadow. The white antler definitely presented the lightest radiograph, testifying to increased mineralization (primarily calcium). The two dark antlers did not differ markedly. Perhaps their calcification levels were too close to be differentiated in such a manner or perhaps the differences in color originated more from the staining chemicals.
The Best Theory
My tests led me to conclude the color of antlers is dependent upon external staining and that the degree of mineralization of the antler affects this staining process; the denser the antler’s exterior, the more resistant it is to accepting stains. The increased calcium and phosphorous necessarily must be available in the diet, so deer that have the luxury of mineral-rich forage or abundant forage are most likely to display denser antlers. So, I believe antler color can vary with local soil quality, local habitat quality, the species of trees and shrubs available for rubbing, and even an individual buck’s level of rubbing activity. The fact that my buck maintained distinct areas of increased mineralization within the overall rack year after year also strongly suggests a genetic component as well.
Editor’s Note: If you’d like to learn more, Dr. Tim Lewis explores the many propounded explanations for antler color along with supporting or refuting evidence in a chapter of his book, Bows, Swamps, Mountains, and Game.