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Magazine


Aging Deer Before Harvest: Turning a Hunter into a Manager

From the Winter 2008 issue

By Steve Demarais, Bob Griffin, and Bronson Strickland
Department of Wildlife and Fisheries, Mississippi State University

The most widely practiced approach to deer management promotes a balanced sex ratio with an adequate number of older aged bucks. Commonly referred to as Quality Deer Management (QDM), this approach requires protection of young bucks from harvest. One of the basic principles of QDM is that the hunter is the manager of the deer population. Every pull of the trigger, every harvest decision a hunter makes impacts the success of their deer management program. Regulating protection of young bucks can be troublesome, as we have learned from our experiences with the “four point rule.” Improved education must be the foundation of future selective harvest systems designed to promote older buck age structure. Hunters must fully accept their role as deer population manager.

One of the simplest facts about antler growth is the direct relationship between age and antler size (Figure 1). A yearling buck will grow antlers that are only 25-30 percent of his maximum Boone and Crockett score. One of the surest ways to double the size of antlers is to let bucks grow from one to two years of age, since at two they will have reached about 60 percent of their ultimate score. Three-year old bucks have about 75-80% of their antler growth, but it takes a four-year old to reach 90-95 percent of his potential. In the Mississippi State University deer pens, bucks reach maximum antler development at five years. In South Texas, wild bucks maximized their antler size about a year later. The age at which a buck reaches his maximum antler size will vary among individuals and be affected by their nutritional resources.

The presence of adequate numbers of older age bucks on a property will improve the hunting experience. Like many of you, we have hunted on properties with an unbalanced sex ratio and limited older bucks. And just like you, we’ve enjoyed the experience of hunting on properties operating under the principles of quality deer management. Who can forget the first time they heard or say two older bucks with antlers locked in dreadful battle, hooves pounding and backs arching, as they struggled for dominance. As fast as it started, it was over, the winner chasing the loser while vocalizing a buck wheeze. The exhilaration of the hunters’ first successful rattling experience is one that can be told and retold to friends over the campfire – but that experience is limited without an adequate number and age structure of bucks.

Aging bucks prior to harvest requires using a combination of physical features. This approach is not exactly quantum physics, but it does require a commitment to learn identifying features and a desire to learn from your experiences. A few “mistakes” are expected: land managers and hunters should treat honest mistakes as opportunities for learning. Using a combination of features does not guarantee 100% accurate aging, but the potential benefits greatly outweigh the limitations. Publications are available on this topic from the Department of Wildlife and Fisheries, Mississippi State University, by calling 662-325-3133.

Physical Characteristics

Whitetails are like people in the sense that the overall body appearance changes with age. The general appearance becomes “more mature” as the buck ages from year to year. By judging the general overall appearance and then focusing on specific body characteristics, it is possible to place bucks into one of several age classes.

Selective harvest to meet the specific needs of individual deer management programs requires that bucks be aged based on general physical characteristics. Specific antler characteristics such as minimum inside spread or minimum number of points can help protect certain young deer. Antler characteristics alone, however, may not provide the needed level of resolution for all selective harvest applications. For example, many mature bucks’ antlers never exceed 8 points and a 16-inch inside spread. Even general appearances change during rut; an older buck may lose up to 25 percent of his body weight due to increased activity and decreased food consumption.

11⁄2-Year-Old Buck (Yearling)

It is often said a yearling buck resembles a “doe with antlers,” which makes it relatively easy to discern. The 11⁄2-year-old buck will not have developed the swollen neck and muscular characteristics of older bucks. These bucks tend to have thin hindquarters and long, thin legs. Think of a teen-aged boy not yet reaching full height and not nearly “filled in.” Almost all yearlings have an antler spread less than 13 inches. These “teenagers” have not learned to be as secretive as their older associates, so they often enter food plots earlier than older bucks and tend to be in the vicinity of doe family groups. The average size of a buck’s antlers doubles between 11⁄2 and 21⁄2 years of age, so it is a good decision to let a yearling buck grow at least another year.

21⁄2-Year-Old Buck

The 21⁄2-year-old group is more difficult than yearlings to judge. During rut, this age class produces a limited amount of neck swelling due to muscle development, and the waist, or area just in front of the back legs, is relatively thin. Their hindquarters are much more filled in than the yearling, but their legs appear to be “long and lanky.” This age class has lots of growing to do before reaching full maturity, so it is best to let them grow at least another year. Their racks are only about 60 percent of their maximum size.

31⁄2-Year-Old Buck

The ability to distinguish the 31⁄2-year-old age group is important to a management program emphasizing harvest of mature-aged bucks with maximum antler development. During the rut, the buck’s neck is thickly muscled, yet there is still a distinct junction between the neck and shoulders. Some biologists compare its look to that of a well-conditioned racehorse. The chest region may begin to appear deeper than the hindquarter area; inside spread of antlers typically is at or outside the ears. These bucks can develop impressive antlers, especially on well-managed properties in productive habitats. They are easily mistaken for “mature” deer; in reality, they have reached only 75-80 percent of maximum antler development.

41⁄2-Year-Old Buck

White-tailed bucks physiologically mature by 41⁄2 years of age. By this age they have almost all of the adult body mass and have lost the racehorse look. The neck region is fully muscled, giving the appearance of blending into the shoulders, and the waistline is as deep as the chest. Buck activity patterns have changed by this age because of an increased wariness; they may not venture into open areas until about dark. Physiological maturity is closely associated with the maturing of a buck’s antlers. By this age, the average buck will have grown about 90 percent of his total antler size.

Mature (51⁄2- to 61⁄2-Year-Old Buck)

Fully matured bucks have a distinctive look that is undeniable once experienced. We group deer 51⁄2 years old and 61⁄2 years old into one age class because few hunters or managers will want to try to differentiate between these animals. Antler size typically peaks at 51⁄2 or 61⁄2 years of age and may deteriorate thereafter, depending on forage conditions. During the rut, the buck’s neck blends completely into his shoulders, and his front half appears to be one large mass. His legs appear shorter than legs of younger deer, but this is an optical illusion because his chest is taking up more of the viewing area. Just as people in middle age, most mature bucks exhibit a sagging belly. Mature bucks often show battle scars such as torn ears, broken antler tines, and scratched necks.

Over-Mature (71⁄2-Year-Old and Older)

Over-mature bucks may be mistaken for younger animals because some characteristics tend to revert. Muscularity is lost in the neck area because these animals may not participate as frequently in normal rutting activities. A swayed back and a prominent potbelly are other signs of this aged buck. Loose skin develops on the neck and head areas as muscle tone declines. Recent battle scars may not be visible, but old scars such as slit ears are evident. A buck’s antler size tends to decline with advancing age.

Hunter as Manager

Although the harvest process is more of an art than a science, you must base harvest on the best science available and practice the art diligently. This article provides additional insight into the art of aging live deer and helps sharpen skills needed in making harvest decisions. Ultimately, the deer hunter becomes the deer manager. Maintaining a healthy deer population should be a goal of any deer management program. This is the responsibility of all hunters, who with each harvest, contribute to the future of this magnificent game animal.