Can I Improve Antler Size of my Deer by Culling Bucks?

Studies conducted in pens at the Kerr Wildlife Management Area by Texas Parks and Wildlife Department (TPWD) biologists led to recommendations that antler size could be improved by culling yearling (1.5-year-old) bucks.  Spike bucks were first identified as genetically inferior, but biologists later recommended culling yearlings with fewer than 6 points.  There was controversy over these recommendations in some circles, which led to a need to verify the pen research in the field.  The first field study was done on the King Ranch from 1999-2005 and was designed by TPWD biologists and overseen by King Ranch biologist Mickey Hellickson.  The King Ranch study was inconclusive and led to recommendations for future research to increase the culling harvest rate and use high-fenced study areas.

After the King Ranch study ended, Donnie Draeger, manager of Comanche Ranch, designed a follow-up study, involving a “moderate” culling treatment area (19,716 acres) and a control area (5,251 acres) with no culling, both in high-fenced pastures.  When TPWD biologists heard of these plans, they asked Comanche Ranch to add a third high-fenced pasture (3,716 acres) with an intensive culling treatment that they designed. In the moderate treatment, no yearlings or 2.5-year-olds were harvested; however, 3.5-4.5 year-olds with less than 9 points, and 5.5 year-olds or older with antlers scoring less than 145 gross Boone and Crockett (B&C) were to be culled.  For the intensive treatment, yearling bucks with less than 6 points and 2.5-year-olds with less than 8 points were culled.  For older deer in the intensive treatment, culling criteria were the same as for the moderate area.

We captured bucks with helicopters and net guns in each of the 3 areas for all 13 years of study.  We culled bucks from 2006–2012, and then kept capturing during 2013–2018 to see if there were delayed reactions to the culling. All captured bucks were aged and measured for gross B&C. During the culling period, we culled bucks at capture with a captive bolt gun if they met culling criteria.  Bucks exceeding the criteria were released after a microchip was inserted at the base of an ear for future identification. 

We captured 6,675 bucks during the 13 years, of which about half were recaptures.  In the intensive treatment, 365 bucks were culled during the 7 years of culling.  For the moderate treatment, 878 bucks were culled.  Buck numbers in both culling areas declined sharply, with the intensive area buck population declining 88%.  The criterion of culling yearlings with less than 6 points, a criterion originating from the TPWD pen studies, did not appear viable for this population.  We harvested 92% of the captured yearlings in the intensive area using the 6-point criterion, which was unsustainable.  The average yearly harvest rate of culled bucks in the intensive area was 48%, while the rate in the moderate area was 22%.

  
In order for a population to show a genetic increase in a trait, the average size of the trait needs to increase in the sires.  In the intensive area, compared to the control area, culling caused no change in average antler size of yearlings and 2.5-year-olds.  Those 3.5–4.5 years old and greater than or equal to 5.5 years old, increased 9–10 B&C inches on average by the end of culling in 2012.  In the moderate area, only those greater than or equal to 5.5 years old increased (about 4 inches) compared to control.  Moderate 1.5, 2.5, and 3.5–4.5 did not increase.  At the end of monitoring in 2018, compared to the control area, antler size was smaller in 1.5, 2.5, and 3.5–4.5 age classes in both culling areas, while the mature bucks showed no difference versus control.   Thus, although culling increased average antler size in some age classes, 6 years past the end of culling, young deer were smaller, while mature deer were not different from control.  These results showed no evidence that culling caused a genetic improvement in antler size.

However, in regard to benefits from culling, there was another important result from the Comanche Ranch study.  Yearling bucks with smaller antlers for their age class were also smaller at maturity.  This was not caused by genetics but by environmental factors affecting the young deer.  Perhaps they were born late or in a drought.  Maybe their mothers did not produce enough milk, or any of a variety of other factors.  For managers, culling smaller young deer can be a good practice, but it is unlikely to cause genetic improvement in antler size.

So far, we have discussed culling to increase the average antler size by age class of the population.  However, what if I have a big buck and just let him walk so he can breed?  Won’t that result in individual big-antlered offspring?  The answer is maybe, but the chances of success of this practice are not great.  We also conducted genetic research during the Comanche Ranch study.  White-tailed deer have a breeding system whereby a buck forms a short-term tending relationship with a receptive doe.  However, they cannot search for receptive does and form more than a few tending bonds in a rutting season.  We found that bucks only produce, at best, a few male offspring per year.  And, not many of the offspring produced survive to grow antlers.  Does are not culled, but form half of the genetics for antlers in offspring.  There is a broad array of alleles for antler size in the doe population.  Therefore, the chances that a large buck will mate with a doe with good antler genes in a particular year are not great.  Also, our genetic research at Comanche Ranch showed that some large-antlered bucks actually do not have good genes for antler size.  So, the buck you let walk actually may not be a good breeder because environmental factors, rather than genetics, produced the large antlers.  Bottom line:  not harvesting a buck to let him breed another season involves sketchy odds that he will produce some good antlered offspring.

Culling inferior bucks can be a good practice for managers. There is no use carrying bucks on the property that you do not consider desirable for harvest.  However, increasing antler size through genetic change from culling is unlikely.  Protecting large bucks from harvest to potentially let them breed could possibly produce superior antlered offspring, but the chances for success are not great.

Charles A. DeYoung is a Research Scientist and Professor Emeritus at CKWRI. Don A. Draeger is manager, Comanche Ranch, and earned a M. S. degree through CKWRI at Texas A&M University-Kingsville.

This article originally appeared in the Spring 2026 issue of Caesar Kleberg Tracks Magazine.