To Cull or Not to Cull?

For many deer hunters, that is the question.

The practice of deer management has grown by leaps and bounds in the Magnolia State over the past few decades. Most whitetail enthusiasts understand that there are three primary factors that have an impact both on body size and antler quality — age, nutrition and genetics.

The implementation of deer management programs aimed at increasing the average age of bucks and the nutritional level for the deer herd has resulted in far more older bucks with impressive headgear out there roaming the woods. This dramatic improvement has created an interest in improving the third piece of the antler formula — genetics. And since importing new genetics is an illegal practice in Mississippi, many deer managers have turned to culling bucks with undesirable antler traits in an effort to improve antler genetic potential.

This practice works well in captivity because specific bucks can be mated to specific does, but is culling an effective management strategy for improving the antler quality of free-ranging bucks? Let’s take a look at a couple of case studies, and see what the experts have to say.

“The practice of culling is not one I would recommend for the vast majority of management situations,” said Dr. James Kroll, also known as “Dr. Deer” in management circles. “It is an unproven practice, which has a place only after the herd has been finely tuned to realize its production and antler potential.”

Determining what constitutes a cull buck is the heart of the problem of this questionable practice. Even biologists cannot agree on what they consider a cull. Some very good deer-management programs have suffered major setbacks as a result of misdirected culling of young bucks with abnormal antler characteristics, including broken main beams, broken points, mismatched points and slight deformities. The sad part is that many of these young, culled bucks could have developed into quality animals. After all, dead deer don’t grow bigger antlers.

Studies conducted by Dr. Harry Jacobson, professor emeritus at Mississippi State University, on a captive deer herd revealed that little or no improvement in future antler quality can be expected by culling based on yearling antler traits.

Jacobson based his conclusions on the examination of 220 yearling bucks raised at the MSU deer-research facility. As yearlings, the bucks exhibited a wide range of antler characteristics from tiny spikes to respectable 10-pointers. Interestingly enough, the best 5 ½ -year-old set of antlers in the research project arose from a spike. Even at 2½, it was difficult to predict the antler-producing potential of a buck at maturity.

Research conducted by Ben Koerth and Kroll measuring the culling effects on antler development in a wild deer population mirrored the results observed by Jacobson’s captive herd studies.

Using helicopters and net guns, Koerth and Kroll captured and tagged more than 400 fawn and yearling bucks to serve as known-age animals. All of these bucks were marked for individual identification with numbered and color-coded ear tags indicating year of birth. Over subsequent years, the researchers attempted to recapture and examine as many of the marked animals as possible. Some of the bucks were also taken by hunters.

The yearling bucks in the study were divided into two antler-point categories. One consisted of yearlings with three or fewer points, while the other was made up of yearlings with four or more points.

The data revealed that the bucks starting with three or fewer points lagged behind their larger yearling antler counterparts through age 3½ years. By 4½ years, there were no differences in any antler measurements between the two yearling antler point groups. Therefore, this study showed that culling young bucks based on antler characteristics will not increase overall mature-buck antler size.

In a second parallel study using the same yearling antler point categories, Koerth and Kroll used Boone & Crockett scores to compare antler growth across the two classes over time. The results were the same.

“By the time the bucks in our study had reached 4½, there were no significant differences in any of the B&C measurements, no matter what the buck started out with as their first set of antlers,” said Kroll. “They were just as wide, just as heavy, had just as many points and had no significant difference in gross score. The same trend holds up for bucks reaching 5½ or older.”

Far too many hunters use the “cull” excuse for harvesting sub-par young bucks, but it should be obvious from the research conducted by Kroll, Jacobson, and Koerth that culling bucks based on their first or second set of antlers is risky business.

“A good analogy might be to look at a 10-year-old boy and try to predict whether or not he will become a star basketball player,” said Kroll. “If this were a common practice, a lot of great athletes would have been ‘culled’ at an early age.”

If there is any place where deer managers could make an improvement in antler quality through culling, it is on the King Ranch in South Texas. But even on this massive 825,000-acre ranch that practices intense trophy-deer management, culling proved to be unsuccessful.

“Over eight years of intense culling, we weren’t able to show any benefits in terms of improvement in antler quality,” said Dr. Mickey Hellickson, chief wildlife biologist at King Ranch.

An alternative to the practice of culling “inferior” bucks is to maintain the herd at a high nutritional plane by harvesting adequate numbers of does combined with limiting the buck harvest to mature (at least 4½-year-old) bucks regardless of antler quality.

This method maintains the genetic variability of the herd by allowing more bucks into the older age classes, and at the same time provides these bucks with a higher level of nutrition necessary for maximum antler growth.

The biggest problem with this method lies in hunter restraint. Hunters must learn how to effectively age whitetails on the hoof. Failure to do so will ultimately result in excessive numbers of young bucks being harvested by mistake.

Genetics and culling certainly are interesting aspects of managing whitetails, and they’re fun to debate around the campfire. But genetics has been proven to be the least important of all the factors leading to the production of free-ranging trophy-class whitetails. In fact, the final antler development of a buck at maturity is dependent upon a host of factors, only a few of which are inherited. And don’t forget that half of the genetics for antler development comes from the doe.

Numerous studies have shown that you must be in total control of your buck population before considering culling as an option. This means that you must either have a high-fenced property or own a huge piece of land. Neither is an option for most deer hunters in the Magnolia State. And even where these conditions exist, the practice of culling has had as many failures as it has successes.