Defend, Display or Duel: What Are Antlers Good For?

July 28, 2016 By: Kip Adams

Antlers are like the beards on guys at hunting camp – they are secondary sexual characteristics that separate females and males but don’t directly contribute to reproduction. So, why exactly do bucks grow them? 

There are four main theories as to why bucks grow antlers. According to noted deer researchers Drs. Steve Demarais and Bronson Strickland from Mississippi State University, writing in the book Biology and Management of White-tailed Deer, the four theoretical functions of antlers are:

  1. Defend against predators.
  2. Display dominance to other bucks.
  3. Display genetic quality to does.
  4. Duel other bucks.

Before I narrow these down to the one function that is most important, which do you this it is? Here is what the experts say.

Defend Against Predators?

Bucks certainly can inflict a hurting with their antlers. Just ask anyone who has worked at a deer research facility how dangerous bucks can be during the rut. However, if this was the main purpose for antlers, then does would have them too. Also free-ranging bucks run from predators and only fight with their antlers as a last resort. Thus, this theory is likely not the main purpose of antlers.

Display of Dominance?

Prior to the rut, bucks routinely establish a pecking order of dominance status. If this was the main function of antlers, then the largest-antlered bucks would be at the top, regardless of age, body size and attitude. This clearly is not the case, and many lucky hunters have watched younger bucks with large antlers make way for older or larger-bodied bucks with smaller antlers. Antlers display information to other bucks, but this theory does not likely explain the main reason for them either.

Display of Fawn-Daddy Potential?

Here is where things get very interesting. Antlers typically get larger with age, so larger antlers can signify older bucks that have successfully survived a few seasons. Larger antlers can also signify good nutrition, suggesting the buck was able to locate high-quality food and was healthy enough to convert a portion of those nutrients to antler growth. These are both meaningful attributes, but a whitetail’s breeding ecology is very different than the harem style of an elk or red deer.

A whitetail doe does not travel with a pre-determined breeding partner prior to estrous. Conversely, does typically breed with the most dominant buck available at the exact time she is in heat. The dominant buck may have recently won the right to breed by defeating other rival bucks, or he is simply the only buck in the area at the crucial time. We know from DNA studies that bucks of many ages, including yearling bucks, successfully breed does. This happens even in populations with abundant mature bucks. Hence, this theory is likely not the primary reason for antlers either, although it is quite possibly a secondary reason.

Weapons for Dueling Other Bucks?

Since this is the final theory, and the prior three were discounted, we have a winner! Antlers in whitetails most likely evolved to be used for fighting other bucks. Unlike bighorn sheep that “ram” heads or bears that stand and fight, whitetails lock heads and push each other around to establish dominance.

Antlers are the perfect structure to accommodate this style of fighting. Bucks can and do injure other bucks with their antlers while fighting, but I contend that’s not their main goal. If bucks were primarily trying to injure or kill other bucks, then they could do so at a much higher rate by attacking foes in the body rather than the head. Fights among bucks are typically well choreographed and proceed through an escalating series of vocalizations and body posturing before reaching the fighting stage that nearly always begins with the bucks locking antlers prior to pushing each other. It’s akin to a reverse tug of war where participants must first grab the rope and get in position before the pulling can begin. Bucks first lock antlers and then use their body size, strength, and attitude to exert their dominance. An antler’s structure even helps support this as they contain more collagen than long bones like femurs, and this permits more flexibility and allow antlers to yield more before breaking.

Whether your personal affinity for antlers lies more in their size or shape, whether you hunt them most when they’re attached to a buck in the fall or dropped in the woods in the winter, or whether you simply enjoy them most for the wonder of nature they truly are, I hope this information adds to your knowledge and appreciation of these amazing appendages.

About Kip Adams:

Kip Adams of Knoxville, Pennsylvania, is a certified wildlife biologist and NDA's Chief Conservation Officer. He has a bachelor's degree in wildlife and fisheries science from Penn State University and a master's in wildlife from the University of New Hampshire. He's also a certified taxidermist. Before joining NDA, Kip was the deer and bear biologist for the New Hampshire Fish & Game Department. Kip and his wife Amy have a daughter, Katie, and a son, Bo.