“A few spikes raised in pens have turned into big deer at maturity, but it’s rare,” he continued. “But, in the wild, in this study we never had a buck that was a spike as a yearling gross score above 155,” he reiterated. “I think biologists should never let the exception be misconstrued to be the rule when it comes to spike buck harvest.”
As for the third question, the South Texas buck capture project also provided researchers with some good data that enabled them to develop definitive culling criteria for landowners to use. To do this they compared the number of points and the gross B&C scores of the bucks that were recaptured at various stages of their life.
Researchers captured 16, 3.5 year-old bucks with seven or fewer antler points that were recaptured at age 5.5 or older. One of those 16, Hellickson said, had a gross B&C score above 140 at maturity, but none of the 3.5 year-old bucks with seven or fewer antler points that were recaptured as mature bucks broke 150.
They also captured 41, 3.5 year-old bucks that had eight antler points. Two of the 41 had a gross B&C score above 150 at maturity and one grossed above 160 at maturity.
There were 13, 3.5 year-old bucks with nine points. Two out of the 13 grossed above 150 at maturity and one grossed above 160.
Additionally, researchers captured 40, 3.5 year-old bucks with 10 or more antler points. When these bucks were recaptured at 5.5 years of age or older, seven out of 40 broke 160 and 15 out of 40 broke 150.
“The odds were a lot higher that a 3.5 year-old buck with 10 or more points would break 150 or 160 compared to a 3.5 year-old buck with seven or fewer points,” Hellickson explained.
For bucks in the 4.5 age category, researchers followed the same protocol. Over the course of the study, 85 bucks captured at 4.5 year of age had eight points or fewer. When those bucks were recaptured at 5.5 years of age or older, none of them grossed over 150.
“That tells me that it’s pretty safe to cull bucks that have eight or fewer points at 4.5 years of age,” Hellickson told listeners, “because those bucks are not likely to gross over 150 at maturity.”
They also captured 35, 4.5 year-old bucks with nine points that they were able to recapture at 5.5 years of age or older. Two of the 35 ended up above 150; one out of 35 (three percent) ended up above 160, Hellickson said.
Additionally, 75 bucks captured at 4.5 years of age had 10 or more points. Of those 75 bucks recaptured at maturity, 20 grossed over 150 while eight of the 75 grossed above 160.
Hellickson became the wildlife biologist for the King Ranch in 1998, a position he held for 12 years. He used data from the South Texas buck capture project to develop a culling strategy for the King Ranch. The culling categories which were designed and implemented beginning in the fall of 2001 were as follows: any buck with at least one unbranched antler, any buck 3.5 years of age or older with seven or fewer total antler points, any buck 4.5 years of age or older with eight or fewer total antler points, and any buck 5.5 years of age or older with gross B&C score less than 130. Any buck that did not fall into one of those four categories qualified as a trophy.
After implementing the non-quota cull buck categories, the buck harvest on the King Ranch increased dramatically while the harvest of trophy bucks declined. In fact, before the culling criteria were implemented, only about 24 percent of the bucks harvested on the King Ranch qualified as culls. After the culling program was implemented, 87 percent qualified as culls.
He showed a graph of the percentage of trophy bucks, those that grossed over 160, harvested on the King Ranch from 1998 to 2008. In 1998, five percent of the trophy bucks grossed above 160. In 2008 that number had increased to 22 percent.
“You might think, ‘Wow, the culling program really worked; bucks got bigger over time,’ but I don’t think that’s the case here,” Hellickson opined. “Instead, what happened is we reduced the trophy buck quota so the hunters became more selective in what they shot as trophy bucks. And because of the increased selection, a higher percentage of the trophy bucks killed gross scored above 160.”
What the culling program really did, he told listeners, is provide for a lot more hunter recreation.
“We forced hunters to shoot fewer trophy bucks, but we gave them a lot more flexibility in harvesting cull and management type bucks.”
Hellickson also told listeners that the culling criteria he implemented on the King Ranch could be considered “pretty conservative” for a South Texas ranch. On ranches that employ a more intensive management program, he suggested shifting the bar up a notch and culling yearling bucks with five or fewer points, 3.5 year-old bucks with eight or fewer points, 4.5 year-old bucks with nine or fewer points and, depending on harvest goals, perhaps consider culling 5.5 year-old bucks that gross score under 150.
So does culling work? To address this question, Hellickson turned to data gathered from the King Ranch culling study, which was being conducted simultaneously with the South Texas buck capture study. The culling criteria were established by TPWD based on results of penned studies from the Kerr Wildlife Management Area. The study was conducted on a 10,000-acre portion of the King Ranch. An adjacent 10,000 acres was designated as the control.
On the control area only five culls were removed over the course of the seven-year study. On the treatment area from 1999 to 2005 researchers removed 158 culls through gun harvest using culling criteria established by Texas Parks and Wildlife. That criteria included every yearling buck with fewer than six antler points and every 2.5 year-old or older buck with eight or fewer antler points, Hellickson said.
He showed a picture of a 2.5 year-old buck with a double drop tine that gross scored 128 captured on the treatment area during the first year of the study. That buck remained on the treatment area for the next five years while 125 inferior bucks were harvested from his neighborhood.
During the second year of the study the buck with the two drop tines was recaptured. At that time he had 17 points and gross scored 161. The following year he grossed 178; at age 5.5 he grossed 199. The buck was harvested the following year at 6.5 years of age. He grossed 190. The point Hellickson was making was that this particular buck offered researchers the perfect scenario to test their hypotheses.
Researchers kept track of the percentage of bucks captured by helicopter net gun on the two areas that still qualified as culls after the culling program was initiated.
“On the treatment area where we were selectively harvesting and removing all cull bucks you would expect the percentage of cull bucks captured at random to decline over time,” Hellickson said. “However, after seven years of intensive culling, the percentage of bucks qualifying as culls on the two areas didn’t change. In fact, in the final year of harvest, 61 percent of the bucks captured at random on the treatment area qualified as culls and 61 percent captured at random on the control qualified as culls. We didn’t see any shift in the percentage of cull bucks between the two areas,” Hellickson told listeners.
Additionally, at the end of the culling period they found no difference in the average gross B&C score of bucks on the treatment area versus the control.
Why, then, didn’t the culling program work on the 10,000-acre treatment area? One potential reason, Hellickson said, is that the culling criteria were less than ideal. Another potential problem, he said, was that the culling program was not flexible from year to year. For example, culling criteria did not change during a dry year versus a wet year. Additionally, both the treatment area and the control were low-fenced. Thus, researchers had a problem with bucks dispersing either from the treatment area to the control or vice versa.
They also found that some of the individual bucks that were recaptured multiple times changed their status as to whether or not they were considered culls. For example, during a wet year a buck had nine points, but if that same buck was recaptured later during a dry year, he might be considered a cull.
Still another possible explanation is that culling mistakes are made when gun harvest is employed.
“One of the worst mistakes one can make is to shoot a yearling buck that was mistaken for a seven point 2.5 year-old buck,” Hellickson told listeners. “That’s why I don’t like culling the 2.5 year-old age class. Oftentimes the biggest yearlings look like small two year-olds and you don’t want to be shooting your biggest yearling bucks. Those are your future 160 or better bucks.”
The final possible contributing factor as to why the culling study didn’t work has to do with individual buck breeding success. In an intensive DNA study, Dr. Randy DeYoung found that no matter the age or the size of the bucks, on average, bucks are only going to sire 1.5 fawns per year.
“So the very low buck breeding success likely contributed to the lack of results from the culling program.”
To put the results in perspective he used what has become known as the “corral continuum” coined by Faith ranch owner Stuart Stedman. The idea is that the closer one moves toward a deer pen situation the more likely a culling program has a chance of success. The closer one moves to a free ranging, large acreage setting the less likely culling will be effective.