Deer Hunters: Do You Believe in Whitetail Culling?

A massive study in southwest Texas indicates that culling “inferior” whitetail bucks isn’t the best way to build a better buck herd.

Deer Hunters: Do You Believe in Whitetail Culling?

Growing up, we were taught by old timers that culling “inferior” bucks were a necessity to upgrade the herd by improving genetics over time. Spikes were Public Enemy No. 1, even if they were young. So, too, were 2- and 3-year old bucks with less-than-perfect antlers.

As the years have passed, I’ve come to believe that culling — here defined as shooting bucks with “inferior” antlers, not thinning an overpopulated herd — isn’t the right thing to do. I’ve seen a set of antlers from a captive deer ranging in age from 1- to 7-years old that illustrated this. The early years showed antlers that were “meh.” But at age 4, things started to change, and from 5-7 years of age, that buck was a stud.

I read a report published by the National Deer Association, conducted on the Comanche Ranch of southwest Texas by serious researchers — biologist Donnie Draeger, Dr. Charlie DeYoung, Ph.D. student Masa Ohnishi, and Dr. Randy DeYoung of Texas A&M-Kingsville, and Dr. Bronson Strickland of Mississippi State University — that says just the opposite.

“Some hunters are so tied into the idea that culling works, that they will say they have big deer because of culling,” Draeger said. “Our data suggests they have big deer in spite of culling, which means they’ve done other things really well — increasing nutrition, passing young bucks, and all the other things NDA preaches.”

Three areas on the ranch were studied — an “intensive” culling treatment area (3,500 acres), a “moderate” treatment (18,000 acres), and a “control” area where no culling would be performed (5,000 acres). Other than size, the three areas were similar in habitat and herd characteristics.

Each fall from 2006 to 2015, helicopter net-gun crews captured bucks in all three treatment areas. Researchers estimated each buck’s age based on tooth replacement and wear, plus they collected a DNA sample, measured the antlers, and inserted a microchip PIT tag in the ear. For seven of these years, captured bucks in the intensive and moderate treatment areas that didn’t meet the respective culling criteria were killed under scientific research permits issued by the state. The rest of the bucks were released, including all bucks captured in the control area. In all, 4,264 captures were made of 2,503 individual bucks (many captured on multiple years), and 1,333 of those bucks were culled. This was a big study!

Firing nets from a helicopter is an effective capture method in southwest Texas. More than 2,500 unique bucks were captured for the study, most of them multiple times across several years of research.
Firing nets from a helicopter is an effective capture method in southwest Texas. More than 2,500 unique bucks were captured for the study, most of them multiple times across several years of research.

Culling criteria used were as follows:

  • Intensive: Yearlings with less than 6 antler points, 2.5-year-olds with less than 8 points, 3.5- to 4.5-year-olds with less than 9 points, and bucks 5.5 or older scoring less than 145 gross Boone & Crockett inches were culled.
  • Moderate: 3.5- to 4.5-year-olds with less than 9 points and all bucks 5.5 or older scoring less than 145 gross Boone & Crockett inches were culled.
  • Control: No culling. All captured bucks were evaluated, tagged and then released.

 

Study Results

In the intensive area, 85 to 100% of yearlings captured met the culling criteria, even though DNA studies ultimately revealed that many of them had fathers that were not cull-bucks. Essentially, this crashed the buck population. What had been a 1:1 ratio of bucks to does became 1:6 due to culling.

In the moderate area, no negative effects on the buck-to-doe ratio occurred, but after 7 years, there was no evidence of successful genetic change. Also, the average B&C score of the standing crop of bucks in the moderate area was the same as it had been at the outset.

That was also true in the control area.

Takeaway: Despite one area being subjected to high-tech helicopter capture and culling for 7 years, overall antler quality in that area remained the same as in the study area where zero bucks were culled.

This buck had the highest “breeding value” out of 2,503 bucks in the study, meaning he produced large-antlered offspring. But his own antlers were only average. He grossed 123 inches at age 6.5.
This buck had the highest “breeding value” out of 2,503 bucks in the study, meaning he produced large-antlered offspring. But his own antlers were only average. He grossed 123 inches at age 6.5.

Study Implications

The important information from this study is why culling didn’t work. A DNA analysis enabled the researchers to connect offspring to 963 buck fathers and build a family tree of fathers, sons and brothers. That allowed the team to build a “breeding value” for individual bucks, which was defined as a buck’s genetic value based on the antler quality of its offspring relative to the average for the population.

The conclusion? If culling is to work, the criteria would need to remove bucks with lower breeding values while leaving bucks with higher breeding values to make more fawns. But the family trees revealed a brick wall: antler size was not correlated to breeding value. Therefore, you cannot predict the breeding value of a buck by looking at his antlers.

Over years of data, the research team found cull-worthy bucks with low-quality antlers that produced fawns that went on to have above-average antlers. They also found bucks with large antlers for their age that produced fawns with below-average antlers. Without being able to trust antler quality as a guide to a buck’s breeding value, a hunter has no way to cull selectively.

“I have no doubt that culling in wild deer doesn’t work,” Draeger said. “Those who think they’ve had success aren’t considering all the other factors involved.”

Those factors include age — achieved by protecting most yearling bucks — as well as nutrition and techniques the encourage mature bucks to use the land you hunt, like managing hunter pressure, establishing sanctuaries, and improving cover.

Many deer hunters incorrectly believe that killing bucks with so-called inferior racks eventually results in bucks with bigger racks.
Many deer hunters incorrectly believe that killing bucks with so-called inferior racks eventually results in bucks with bigger racks.

Photos courtesy of National Deer Association

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