Wild Deer Culling Research pt.1 - The King Ranch Study

Long debated in deer hunting stories, the subject of wild deer culling for genetic improvement is a debate that never dies, but there is a lot of sound research that has examined this question. This is the first of a three part series reviewing the results of genetic culling research. On this episode we're joined by Dr. Mickey Hellickson to discuss foundational deer culling research that he helped lead on the famous King Ranch looking at genetic culling via hunting in a free-range setting.

 The full study can be found below

https://wildlife.onlinelibrary.wiley.com/doi/pdfdirect/10.1002/wmon.70013

Transcript

Moriah Boggess 0:01

Welcome

Intro, Event Announcement & Guest Welcome

Moriah Boggess 0:02

to Wildlife Investments, where we discuss wildlife research, habitat, hunting, and land management with our panel of leading resource managers. Wildlife Investments, resource management by scientists. Hey y'all, August 29th, Raymond, Mississippi. We are holding our Deer Management Academy. You're not going to want to miss this education-filled day on everything from the basics of deer biology to nutrition, diet selection, property layout, how to make habitat management decisions on your property to reach its fullest potential. We're going to cover it all so that you can manage your property like we manage ours. Go to our website, click on the education events tab, and you'll be able to buy tickets there. And if you hurry, you can probably still get a ticket for the social event we're holding the evening before. It's going to be a small crowd. We can all get to know one another. Talk management, it's going to be a good time. So we hope to see you this August.

Dr. Bronson Strickland 1:04

Okay, welcome back to the Wildlife

What Is Culling & Why Does It Matter?

Dr. Bronson Strickland 1:07

Investments podcast. We have an episode today that I'm I'm very excited about. It's something that I've been really, really lucky to be a part of over the years. And it is it is again the topic of culling, the very controversial topic of culling and trying to remove certain bucks to have genetic change in the population and genetically making improvements. So the average Boon and Crockett score of your bucks is larger. We're going to be showing some data with this episode. And so certainly you're going to be able to follow along and we're going to describe the results at all, but you may want to watch it just so you can also see some of the data we're we're going to be presenting. And joining me today, of course, is Moriah Boggess, and our guest is Dr. Mickey Hellixon. And Mick and I go way back. Mick, I think that may have been one of my first jobs in the in the wildlife deer management field you hired me for. What year was that? 1992, maybe?

Dr. Mickey Hellickson 2:21

Yeah, it could have been as long as 1992. It might have been 1993. I know you've you stuck, we had a hard time getting rid of you, Bronson. You stuck around for a second quarter or semester. And yeah so.

Dr. Bronson Strickland 2:32

Took one for the team. That's exactly right.

Dr. Mickey Hellickson 2:35

But you know, you think it was the high pay though that kept you around, right?

Dr. Bronson Strickland 2:39

It it was the it was the high pay, which was none. You know what really? I'm sure we talked about this a lot back in the day, but one of the main reasons when when I came to work with you, it was I was an undergrad at the University of Georgia at the time. You were a PhD student at the University of Georgia, but your study area was in South Texas on the Faith Ranch. But I came during the summer, that that first quarter, it it was quarters then, not semesters. It was during summer, and obviously it was a very different environment than what I was used to, and it was very, very hot. But when you and Dr. Marshington made the request of being a possibility to stay on, it I wanted to be down there during the rut, during hunting season. I mean, I didn't want to just see South Texas in the summertime. I wanted to see it in the fall and and experience that. And I have zero regrets. It was, I think I've told you, one of the best things I've I've ever done. The one thing I haven't heard you say either ever or lately, I haven't heard you comment, Mick, on how good of a technician I was, and not to put words in your mouth, maybe the best you ever had?

Dr. Mickey Hellickson 3:53

Hands down, Bronson. Yeah. No, you were one of the best.

Dr. Bronson Strickland 4:03

I'm just kidding. I'm just kidding, trying to have some fun. So we're going to talk about another phase of Mick's life. Mick then ended up becoming the the chief biologist for the King Ranch and a study that he and other people led on the King Ranch regarding calling. And I want to be sure here at the onset, I want to acknowledge everybody, because so many people played a part in here. So I just want to run through and read the title and the affiliations of everybody. So the the name of the study, which is part of a recently published monograph, so this would be one of the papers or chapters within that whole monograph, is called Influence of Selective Harvest on Antler Phenotype, an experiment with free-ranging whitetailed ear. Study was conducted by the King Ranch, Texas Parks and Wildlife, Caesar Clayburg Wildlife Research Institute at Texas AM University Kingsville. Co-authors, Mickey Hellikson, King Ranch, Randy Fugate, Texas Parks and Wildlife, Charlie DeYoung, Dave Hewitt, Maso Nishi, Dave Wester, all from the Caesar Clayburg Wildlife Research Institute, and I'm bringing up the rear myself from Mississippi State University. So kind of getting that out of the way to acknowledge everyone. But the purpose of the study was Mick, can you change age-specific antler size? Can you make bucks bigger in a free-ranging deer population using recreational hunting or recreational hunting meaning calling as your selection mechanism? So that was the point of the study. But Mick, I'm gonna hand it over to you next, if you don't mind. Maybe talk a little bit about the King Ranch, talk about how this came to be, the study came to be, and and then I think we need to talk about some other research that really led to this, and that was the research that occurred at the Kerr Wildlife Management Area.

What Sparked the King Ranch Experiment

Dr. Mickey Hellickson 6:17

Yes, Bronson, the um the folks at the Texas Parks and Wildlife Department approached the King Ranch about conducting a follow-up or a field study to research that they had done in a captive deer facility at the Kerr Wildlife Management Area. And they found some very compelling results of that study showing dramatic and fairly quick changes in yearly and antler size based on some selection criteria that they applied to those captive deer. And they felt that with those results, you know, it should also work in the wild. And so the King Ranch was asked to serve as a study site for the study. And with me being the chief biologist for the King Ranch, I kind of inherited this study, but it fell right into another study that we had started one year before this, the South Texas Butt Capture Project, that was started in 1998, and then our first year involving the King Ranch was in 1999.

Dr. Bronson Strickland 7:16

Before we get into the results of the Kerr WMA study, Mick, one thing I have up here, of course, they were in research pens. That was an enclosed population, so they could manipulate the population. They allocated all of the selection on yearlings and then and then looked at change over time with yearlings. Why did they use such a limited diet of 8% crude protein for these research animals?

Why Low Nutrition? The Science Behind the "Swing Deer" Theory

Dr. Mickey Hellickson 7:49

Yeah, they called it the the swing deer that are the biggest portion of the bell curve. You have the outliers to the right, which are your very biggest yearling bucks, the outliers to the left, which are your very smallest yearling bucks, short, short-length spikes, for example. But the bulk of the deer in the middle, 70-80%, they termed those as swing deer. And in a drought situation where nutritional levels are decreased, they they felt like they hypothesized that a high percentage of those swing deer would swing left and and and show smaller antlers that reflected that truly reflected that they were not the biggest of the cohort. And it took that stress to be able to recognize the biggest bucks within that cohort, to be able to recognize the the ones that were truly genetically superior for antler size because they did it in a poor nutrition situation.

Dr. Bronson Strickland 8:47

Okay, so it's it's recognizing a proportion, 30, 40, 50, or greater percent of the bucks, some are going to be far more susceptible to environmental influences than others. And the ones that aren't susceptible, the logic is they are truly expressing a genotype for larger antlers. And so it's a mechanism to identify the ones that are truly special genetically.

Dr. Mickey Hellickson 9:19

Yeah, and and Bronson, that was the method that they used for selecting bucks in in the captive study, right? The they they they gave them a low nutrition, poor nutrition diet, and then the yearling bucks that that had the biggest antlers under that port diet, those are the ones that they selected as sires to breed does. And then it was the offspring, the later offspring of of those pairings that resulted in a in a big shift upwards in population antler size. Yeah.

Dr. Bronson Strickland 9:50

Well, so the the criteria they used, and man, this this is severe, free range, but you know, again, this is in a captive environment. They called all yearlings with less than eight points. And they did that from 1992 to 1999. So we will now let's let's look at what they found. And the the percentage of yearling spikes, you can see in the the data here, it changed pretty dramatically over the course of their study, again from 92 to 99. So the the first year of the study, 33% of the yearlings were spikes. By the end of the study, it was only around 3%. So a pretty dramatic shift. Again, all indicators, indications are that this this is working. And another way to look at it, the percentage of yearlings that had eight or more points was only three percent when they began the study, and it was almost half at the end of the study. Forty-eight percent of the yearling bucks had eight or greater points. Another way to look at it, we kind of you know framed everything in the previous two slides with proportion spikes, proportion eight or greater, and this is just a display. And by the way, this is from the Texas Parks and Wildlife website. So anybody can go to their website and find these graphs. But we're basically starting in year one, the average antler size, uh, number of points, average number of points in yearless is about four. And then year by year, progressively it gets larger, larger, larger, and they end up with the average number of points of yearlings being about seven and a half. So over that number of years from 92 to 99, it's almost a doubling of the at least going by number of points. So yearling bucks got a lot larger. So definitely a tangible increase. And so, Mick, maybe it was about this time, these results to me were very compelling. And what can be done in a controlled environment. And so this is, I guess, when they approached the King Ranch and you and others, Charlie D. Young at AM Kingsville, about hey, let's try to do a field study and see what we can do in the wild. Right. So the King Ranch endeavor

The King Ranch Study Design

Dr. Bronson Strickland 12:32

begins. So now we're in a free range scenario. We've got two really big treatment areas. So two areas where the experiment, the culling experiment was conducted. The treatment area, that is where culling took place, and that's over 9,000 acres, and a very comparable control area where no directed culling took place was again over 9,000 acres. And at their closest points, Mick, they were they were over two miles apart. But again, that's that's at the very closest point. They're point they're irregularly shaped. But if you probably went from center of the treatment area to center of the control area, well, it was probably what six or seven miles apart. Yeah, yeah, approximately. And then based on the CERS study, you had two culling criteria or two main ones. And so all yearling bucks with less than six points were to be called, and all bucks two and a half or greater that had less than nine points were to be called. And so to me, and and I'm I'm biased by the environment I live in and work in now, but I look at that Mick as that's pretty severe.

Dr. Mickey Hellickson 13:57

Very severe criteria, very severe, yeah.

Dr. Bronson Strickland 14:01

One thing that that y'all did, and and other studies we'll talk about later, that I think is really, really important is how you assessed change in the population. And so what y'all did, Mick, and and you can of course describe this a heck of a lot better than me, but before every deer season, y'all incorporated helicopter capture so that you had a non-biased, not at the skinning shed sample. So you're able to go out there and randomly sample all of these bucks, net gun them, get them on the ground, age them, measure their antlers, and then then then you're more able to monitor over time is there any progress occurring or not.

Dr. Mickey Hellickson 14:53

Yeah, that's exactly right, Bronson. That was how we judged the success or lack of success of the culling was a random capture by helicopter and net gun of butts on both the treatment area and the control area early in the fall before the the hunting season. And so we got our hands on bucks at random, and we were able to age them by tooth wear, measure their antlers, photograph them, take DNA samples, and and then release them before we did the colon each hunting season.

How Progress Was Measured & Unbiased Sampling

Dr. Bronson Strickland 15:30

So, guys, we have to make sure that we don't fall into the trap that a lot of people do and thinking my my standing crop of bucks is now larger at the end of hunting season, and therefore we made progress with culling.

Moriah Boggess 15:48

When you say larger, their mean antler score, not meaning.

Dr. Bronson Strickland 15:51

Mean antler score is larger, yeah. But because all you did, which is the process of selective harvest and culling, is to remove the lower quality animals. And so by removing the lower quality animals just in one year, you're gonna have a different average boon and crockett score at the start of deer season and at the end of deer season. So we didn't make any genetic progress there, but we did change average boon and crockets score of a particular age class because we removed all the lower quality animals. The slide that we're looking at here would be indicative of there is something going on, we would think genetically, and that is by looking at offspring. And so if you'll notice what I have depicted here, there's a white line meaning control or no calling. And notice over the course of the years there of the study, you're seeing very little change in that white line. So that's just meaning it's just got a little bit of environmental variation, a little bit of sample bias, maybe from years to year from year to year, but there's no change in the average. If you look at the red line, that is representing what we would think would be the culled population. And we're we're starting out at an equivalent number to the control, and then year by year, after we get three, four years into it, we start to see a separation in the average. And what and what that is depicting there is we are now producing greater, quote, genetic, genetically improved offspring. So our yearling bucks are getting bigger and bigger and bigger over time because they are being sired by larger Boon and Crockett score, larger bucks.

Dr. Mickey Hellickson 17:53

Yeah, Bronson, exactly. The the Kerr results would have predicted the graph that you provided with the King Ranch data set. That's what you would expect based on their results to happen when when we applied this to a a free-ranging wild situation, right? If if that if the uh if if the choline had that effect, you would expect it to result in this kind of graph. Yeah.

Dr. Bronson Strickland 18:17

I and and really I just kind of want for those that would be watching this, I wanted to kind of set that up for this is what we would predict should happen if it's working, and then we're gonna show what did happen, and then people can decide how different this looks. And so we'll we'll move on now to here's what did

What the Data Showed

Dr. Bronson Strickland 18:37

happen. And so again, this is just only yearling bucks from year to year, and I'm using average boon and crockett score. What should be very apparent, two things jump out at me. Number one, wow, there's a lot of environmental variation. So when you see these swings and and they're more or less consistent, when the control boon and crockett score is greater, so is the treatment area. And we see that they are more or less in parallel, they're both rising and falling more or less on the same year. The other thing that should jump out is there's no separation. So looking at these yearlings over time from 1999 to concluding at 2005, there's no difference at all in in yearling antler size.

Dr. Mickey Hellickson 19:33

100%. I mean, that's exactly what we saw happen with the data, with the capture data before the culling of each hunting season.

Dr. Bronson Strickland 19:43

So that is look for those that might want to look at, yeah, but what about at three or at four years of age, Mick, then plotted at the conclusion or after the culling began. So we want to look at after, you know, we're now dealing with a culled population, and in theory, we have more large antlered sires in the population. Those those bucks that were then born after the culling program began, what are they doing, you know, as they get older? And again, we have the the no no culling and then the the culled areas plotted at the yearling, at two years of age, three, and four, and notice there is effectively no difference at all. It would be harder for those two lines to be closer together, right? I mean Yeah, that's right. I mean, you know, someone could zoom in and go, hey, there's a couple inches different, but that could just be sampling bias. You know, make at that point, four four years of age after the culling began, you also have not that many animals at that time. Sample size is pretty low. But what should jump out to people is that we're not seeing this big disparity that you would predict. When you're putting forth all this effort for all these years removing these lower quality bucks, you would expect a you would hope for a difference of greater than one or two inches. Bottom

What Went Wrong? Culling Rate, Buck Dispersal & Pre-Rut Timing

Dr. Bronson Strickland 21:17

line is it didn't work. It didn't work. And so now we want to talk about what went wrong. And so I guess, Mick, let's just kind of compare, contrast, if if you could do it over, what some things that you think would make it better, what's different about the free range experiment versus what was found with the the Kerr study, and what do we take from all this?

Dr. Mickey Hellickson 21:41

Yeah, well to begin with, the culling criteria, not only were they intense, right, for the yearly and age class, especially, but but they also were not flexible. We we had those same criteria each of the each of the six years of the of the culling part of the study. And in a in a draft. Year, for example, when the percentage of yearling bucks with with five or fewer points increased because of poor nutrition, that criteria called for the harvest of even more yearling bucks because of that criteria. Which looking at the Kerr data set, that's what they were hoping would happen, right? Because those are swing deer showing themselves as coals, right? But they they became available as coals then. And because of the intensive criteria for yearling bucks, 70% of the bucks harvested during the study were one or two years old. So we had a very high coaling rate on the young bucks and a less severe culling rate on the on the bucks two and a half and older, or three and a half and older, especially. But and that was also part of the design. The criteria for bucks two two years old and older shifted to to culling bucks with less than nine points, right? So but not nearly as severe as the as it was for the for the uh yearling buck age class.

Dr. Bronson Strickland 23:05

So I'm thinking about your your effort, and you're talking about 70% of the bucks that were culled were one or two, if I heard you correctly. Was that just out of uh because those are the bucks you're seeing, they're more available for harvest, and they're also naive. You see them more frequently than you're gonna see the mature bucks to harvest.

Dr. Mickey Hellickson 23:27

Yeah, it's a combination of things. Definitely the uh the intensive criteria made a lot of the young bucks available for harvest. A lot of two-year-old bucks have eight or less points, naturally, right? So that's a pretty high percentage of that cohort in addition to the yearling bucks. And they are yearling bucks are more naive than two-year-old bucks in general than three-year-old bucks, you know. And so that's true as well that we've probably harvested a higher percentage of the yearling bucks available because they're easier to harvest, right, versus older age bucks in the study, too. But the the first two years of the culling, we really hammered the coals because of those criteria. We removed a lot of animals the very first two years because there were a lot of animals in the population that met the coaling criteria. By year three, all of those animals removed in year one and two, obviously, they weren't around in year three. And so by the year three, the buck population declined significantly, and the percentage of those bucks that were that were available as coals also declined because we had already removed a bunch of them earlier, right? So the the buck harvest fell off quite a bit years three through six in the in the harvest.

Dr. Bronson Strickland 24:41

At risk of confusing people, we may want to cut this out, Moriah, if it's confusing. I'm wondering what if you saw the effect we were describing earlier, that you you could if you went to the treatment area at at year four, let's say, or year five, versus the control area, did it look different to you, meaning there was the average boon and crockett score of the standing crop was larger. Because you removed all those lower quality young deer.

Dr. Mickey Hellickson 25:15

Yeah. That's what you would expect, but I don't recall having those thoughts that I saw a difference in the cohort, the standing crop cohort from the beginning of the study toward the end of the study, or even within uh the same year, I didn't really notice it. And and it's important to point out now, I think, too, that this was a low-fence free-ranging situation where the bucks were moving back and forth, leaving the treatment area, leaving the control area. There was a lot of movement. And in fact, a uh companion yearling buck dispersal study found that 44% of the yearling bucks in our study in the same area dispersed an average of just over five miles. And so we've got you know buck fawns born on the treatment area that later disperse and become residents of the control area because of the low fence. And so it made the data really messy. But a lot of my clients, Bronson, we do both fall surveys and winter surveys by helicopter on their high fence ranches, right? And so that eliminates a lot of that movement in and out of the area. And on those areas where they're doing intensive an intensive level of coaling, you do see dramatic changes in the cohort, in the standing crop, not the cohort, but the standing crop. Between the fall survey and the winter survey, you change the the standing crop, but of course, that's that's not changing anything yet with genetics because of that's all within one breeding season that that happens, right? So yeah. Yeah.

Dr. Bronson Strickland 26:52

So we did some stuff, you know, very different. You know, the it's one thing to do an experiment in a in a research pen where you can control everything, and you're you're even further removed from reality when you're running a simulation model, which is which is a lot of the the work I did during that time. And you know, what we found with that stuff, Mick, was that the the calling rate was very, very important. And it was actually uh maybe not shocking, but you r typically had to be removing about half or more of the cohort. So not just removing the worst 10%, you need to be removing, you know, 40, 50, 60 percent uh of that cohort to really see some down downstream effects. And so I know you guys put in a lot of work, you especially, a lot of work, a lot of culling. Do you think that could be a criticism of the study that you didn't cull intensively enough?

Dr. Mickey Hellickson 28:01

In a low in a low fence free-ranging situation, I think it would be difficult for other ranches to even reach the levels of culling that we did in this study. We we worked at it very hard, tried, and we have a very long rifled deer hunting season in in Texas that we were able to take advantage for this for with that with this study. We were we were intensively culling bucks from October through February, and that's a pretty long window to be removing bucks based on coaling through hunting, right? And so I think it would be hard for other ranches with low fence and free-ranging deer for them to duplicate the level of coaling that we did in this study. Now, the comparison to a high fence situation or the comparison to a captive facility, yeah, I think Bronson, we removed somewhere around 30-40 percent of the available coals in the treatment area through Hunter Harvest. That is way lower than what needs to be done to really accomplish population level genetic change, I think. The Kerr study found that the rem they they excluded 70 to 85 percent of the yearly and age class from breeding each season, right? And so they were effectively selecting the biggest 15 to 30 percent and eliminating or in in effect coaling the bottom 70 to 85 percent, right? And so that percentage of removal probably needs to occur to see similar results. And in our study, we removed at at best 40 percent, right, of the available coals through Hunter Harvest.

Dr. Bronson Strickland 29:42

You know, you're also dealing with a variable environment. And so one thing, if you're in a research pen, the the the diet quality, even though the the Kerr researchers they they restricted it for the reasons we talked about earlier with an 8%, but but at least it was constant. You know, they they had constant access to food all the time. Where if you're free range and you're especially in South Texas and you know, a rainfall-driven population, you also have swings from year to year in environmental quality, food quality, food abundance, and that is then influencing the very trait antlers that you are selecting and determining if this is a good deer to keep or or a lower quality that needs to be needs to be called. So what is really interesting and valuable with the way you set the study up is by you having those captures and having the control area, and then you have recaptures of the same box over time, you can then determine which box would have switched from a call to a keep or a keep to a call had it been in that treatment area. And so that's something also you identified that a great proportion of deer that would have been culled earlier in life would have been a keeper a year or two later. So yet another inefficiency with the process.

Dr. Mickey Hellickson 31:14

Yeah, definitely. And in our study, we found that about 30% of recaptured bucks changed their status. And the the more common change was going from a cull to a non-cull versus going from a non-cull later to a cull, right? Most of the time it happened where the coal, when recaptured, became a non-coal, right? So but 30% roughly change status. And so that definitely messies up the data set too.

Breeding Success in Whitetail Bucks

Dr. Bronson Strickland 31:45

And then we're talking about genetic change. So again, we're trying to, with calling, you're trying to have a disproportionate influence of the biggest bucks. You want them to be the most common sire of offspring. But what's difficult with that, Mick, what you're describing all over deer season, there's no way you can go and go through and remove the number of bucks that you need to before the rut each year. And so you have another inefficiency that you have a lot of this stuff occurring, selections occurring after the breeding season.

Dr. Mickey Hellickson 32:22

Yeah, you know, we we did the culling through regular hunter harvest with hunts conducted the same way that we conducted our commercial hunts on the ranch. And it would be a guide in a King Ranch vehicle driving safari style hunting with a hunter in the front seat with him, and you're looking through the windshield as you drive by bucks until you find a buck that meets the harvest criteria, and then the hunter typically shoots out the window of the truck. I know all the other states listening to this podcast are going, wow, you can do that? Yeah, you can in South Texas or across Texas, right? And so the hunts, because of the methodology of doing recreational hunting, it's a time-consuming process. And to kill, we removed 158 bucks as coals during the the course of the study on the treatment area. That's basically 158 different hunts taking place. And they're there an out-in's generally a half day. So we're going out in the mornings hunting till lunch, and then going out in the afternoons hunting till till sunset. And if you added up all the hours spent recreationally hunting with that five-month rifle season that that Texas has, you know, not only was a lot of time involved, but a lot of those hunts fell during or after the breeding season. I mean, that's that's to get that level of butts harvested, you you can't do it by hunter harvest, standard typical hunter harvest before the rut. I mean, it doesn't happen. The only way to really do that is to do it through helicopter netgun live capture before the breeding season, which is what the follow-up study did.

Dr. Bronson Strickland 34:04

And speaking of uh breeding season, let's talk about breeding success, uh yet another complication. And let me contrast this with let's talk about elk or bighorn sheep would be a a good example where you have the the harem of male, and you know, he he's dominant, he's defending a harem, and he's gonna do a lot of the breeding. That's kind of the best case scenario for if you wanted to make some type of genetic change, is that you select your handful of sires, and then they are gonna do most of the breeding and sir most of the offspring. But with whitetails, they have a tending breeding strategy, and so they're all individually pairing up, and a lot of bucks are breeding, even yearlings are breeding, even on a place with a good age structure like the King Ranch, even there, yearling bucks are breeding, two-year-olds are breeding. And I think a companion study, Mick, that Randy did, he he measured through y'all samples the average reproductive success. Am I right?

Dr. Mickey Hellickson 35:13

Yeah, one of Randy's three study sites for his PhD was the King Ranch, right? He had a study site in Noxubee, Mississippi, and then one at the Noble Foundation in Oklahoma. His third study area was the King Ranch, and it involved these exact deer that we had and that were involved in this in this coin study with Parfumwalla. His data set for the King Ranch came from the deer that we captured and harvested on the King Ranch. And he got his DNA samples from the butts that we live captured, from the butts that we harvested. And then we also targeted a dough harvest every year in February, where we were effectively harvesting pregnant females because this is two two to two and a half months after peak and conception, and and so their fetuses are one and a half to two months old. And we're able to remove the fetuses, measure their lengths to determine approximate dates of conception for each set of fawns or for each set of fetuses, right? And the the first year of the of the study, our initial dough harvest showed peaks in the peak in conception was December 7th. The sixth year of the study, after we removed 158 culls from the treatment area, and uh five culls had been removed from the control area, to contrast that. That final year of the study, the dough harvest that Randy and I did in February, showed peak conception had shifted ten days later to December 17th, right?

Dr. Bronson Strickland 36:49

So that would just be the the sex ratio getting askew.

Dr. Mickey Hellickson 36:53

Yeah. Randy's study on the on the king ranch portion of his data set, he found that the most fawns sired by an individual buck was five. So there's definitely no harem situation going on because of all the bucks sampled, all the dough sampled, all the fetuses sampled, he he could find no more no situation where more than five fawns were were the result of one buck's breeding, right? And then on average, during the course of Randy's study with our study, the successful bucks, this eliminates all of the bucks that he couldn't find any fetuses to, which was, I guess, somewhere around 25-30% of his buck data set, he couldn't prove that they did any breeding. So now we're looking at a smaller subsection of that data set where we're talking about the 70 bucks, 70% of bucks that were successful. Of those bucks, and average the average number of fawns produced by those successful bucks was 1.6 fawns per successful buck. And that's not in an individual year, that's during the the two or three year window when Randy's collecting DNA for his study. Right? So that's not a single year that they average 1.6. That's over the course of the study. Successful bucks average only 1.6 fawns per buck. And to me, that's a that's a big monkey wrench in the idea that culling can work in, especially in a free-ranging situation, because breeding success for individual bucks, quote unquote, your biggest trophy buck that you leave in the pasture to do all the breeding, on average they only sire about one and a half fawns. And so it's hard to get results with that kind of breeding success.

Dr. Bronson Strickland 38:35

So it's just the opposite. Thinking of a beef cattle operation, everybody's driven down the road, whether you've worked there or or driven down the road, and you'll see all these cows out there, and then you'll see one or two bulls. That's the kind of the scenario that you you would hope for if you're wanting to influence the phenotype or genotype of of your offspring, is you have hand selected this, you know, big bull, and he is gonna breed at least half the females. And that's just the opposite of what we see in in white-tailed deer.

Dr. Mickey Hellickson 39:12

I mean and and think of what happened in the current portion of the study with captive deer. They selected the bucks, and the bucks, the 10 10 to 15 to 20 percent of the bucks they selected did 100% of the breeding. They sub sired 100% of the fawn offspring, right? And none of the other bucks sired any offspring. Well, that's that's not what happens outside of a captive situation where you're able to match up bucks with those in a pinned situation, right?

Dr. Bronson Strickland 39:43

And then, Mick, we've got we've got dispersal, and you you touched on this earlier, but you've got an exchange of deer coming and going. You've got your your regular yearling buck dispersal, so where it was born, and you know, 18-ish months later, it's dispersing and gonna set up a new home range. Then you just even have excursions, you know, during during deer season. So there's all of this coming and going, and uh yet another reason we have such an inefficiency in in a free-ranging context trying to do something like this.

Dr. Mickey Hellickson 40:21

Yeah, and in fact, uh, another study that went on and then overlapped this study was Aaron Foley's PhD work, where he had bucks radio collared, and he was one of the first people to describe with GPS collars what you talked about already was the excursion rates for bucks. And in some cases, and those were bucks on this same study area where some of those bucks are going 10, 12 miles on an excursion, right? So they're going to all different parts around the treatment area and the control area that's impacting our results.

Human Error & the Double Whammy of Failed Culling

Dr. Bronson Strickland 40:56

And then we have human beings, and all human beings make mistakes. And my goodness, Mick, I know you probably felt under pressure a good bit of the time, and even probably from the start of the season where you probably thought you could identify, differentiate a maybe a high-quality yearling and a low-quality two-year-old, but then you start getting into January and February, and resources are limited, and those bucks start getting thinner. I'm sure it was difficult to reliably classify what was a yearling and what was a two plus, and mistakes were made, I'm sure.

Dr. Mickey Hellickson 41:36

Yeah, unfortunately, the biggest mistakes were made when when our biggest yearling bucks that we captured during the study mistakenly were harvested as culls, with the guide thinking that instead of them being very big yearling bucks, they he was thinking they were small two-year-old bucks that qualified under that two-year-old less than nine point criteria, and they were harvested as as thinking they were two-year-olds, and instead they were some of the biggest yearling bucks that we captured in this in this whole study. And and so you're there there's not a worse mistake than that in my mind. And and a kind of a funny story, Bronson. We did this study, of course, in cooperation with Parks and Wildlife. Most of the most of the folks there for the captures were Parks and Wildlife staff. I mean, they they helped out from the beginning to the end of the study, worked very hard on on ATVs, chasing the deer around and throughout the study, but the the guide that happened to mistakenly allow his hunters to harvest these two giant, I'll call them giant yearling bucks, was a Parked Wildlife staff member who after he he mistakenly guided the harvest to that second mistake, he know he was he was barred from then doing any more guiding as a part of the study, right? And so and and to make matters worse, both of those bucks were also radio collared. And and one of those bucks had seven points as a yearling, and because of the collar, the the person should have already recognized he was a yearling buck because that gave away his status. And then the second buck, Bronson, which brings up another way that harvest mistakes can happen. He was he was he had seven antler points when he was captured in October. When he was mistakenly harvested later, he only had five points. He had broken two points, and it's difficult to see a broken point when it it breaks off flush with the main beam. Or when it's an abnormal point off another point or off the burr of the back of the base or something like that. So there's harvest mistakes that happen because of broken points, too. Right? Yeah.

Dr. Bronson Strickland 43:52

So and how ironic the the very buck that would have been selected for in The current study, the one you would have kept to make a sire, is the the the two bucks that were mistakenly harvested as mistakes in the King Ranch study.

Dr. Mickey Hellickson 44:11

We all know, everybody should know, you know, that bell curve distribution, right? And what we're targeting, what we're doing all this effort for is to try to increase the very small percentage of bucks that are in that far right tail of the bell curve. It's only a handful of bucks that make it to that status. And these two yearling bucks were probably weighed to the right on that bell curve, and we removed them. Look at the effect that has, right? And so a recommendation I would make to everybody, especially in South Texas listening to this podcast, is don't even try to cull from your two-year-old age class. Don't even try it. Don't even attempt it. If if you want to, and if your data indicate and your biologist recommends it, and you want to shoot spikes out of your yearly and age class, fine. But don't shoot any two-year-olds because you can really shoot yourself in the foot by by sh you know making the mistakes that we just talked about, and instead start culling again at three plus years old, right?

Moriah Boggess 45:11

So I think one thing that's worth pointing out here, because we've been discussing several shortcomings, if you will, or or limitations of of what was done. But at the end of the day, these study sites were what? Each treatment 9,000 acres, a little bit more. Yeah, 9,500.

What This Means for the Average Landowner in the Southeast

Moriah Boggess 45:31

There's a lot, we've got a lot of people listening probably across the southeast that are on much, much, much, much.

Dr. Mickey Hellickson 45:36

Those are almost unheard of acreages sizes. Yeah.

Moriah Boggess 45:39

So you guys had a a harvest system on this huge acreage. You had guys riding around with hunters, guys who look at deer all the time on those properties to make those decisions. So even though Mick, as you point out, there's a few mistakes, that's pretty negligible. Like you guys did really good to only have a few bad mistakes like that. I mean, Bronson and I see it all the time, every year. I mean, almost, almost without fail, the the biggest and best deer mistakes happen to those deer because they're they they just have so much antler that you know it it clouds people's judgments. So you guys were, you know, you guys were doing so many things right. You had so much working for you, and even in that situation, this was still the result. So just for everybody else listening, you know, think about the scale of it, think about the intensity of harvest that you you all were able to achieve on this project, and then you know, how much care went into the harvest. And even with all of that, it we still didn't see an effect.

Dr. Mickey Hellickson 46:46

Great point, Moriah. And and it I think it's important to point out that uh out of the 158 bucks harvested as culls, there were only three clear mistakes made out of 158. And and again, I I don't think other ranches outside of research situation like we had, not only do I don't think they can they can achieve the level of harvest that we did, I also don't think that they can achieve the level of accuracy that we had in in our selection of culls, right? We were trying to be very exact on that, right? And so great point.

Dr. Bronson Strickland 47:22

Well, Mick, what about revenue? You mentioned there's a possibility of some lost revenue. Explain what you mean by that.

Dr. Mickey Hellickson 47:30

The the King Ranch, the wildlife staff there, they they they felt like by the end of the study on the treatment area that we had shot out all the quality bucks. And even though our survey data from the helicopter didn't necessarily show that, what they were seeing in the field convinced them that we had gotten rid of all of our commercially available bucks for harvest, most of them, through the cohen because of the intensity level of the cohen, right? When you're when you're cropping off 70% of your yearly and age class, that doesn't leave many yearling bucks to grow to maturity. And it's those mature bucks that are important in a commercial hunting operation for re for for gaining some revenue back, right? And the King Ranch, not only do we did we harvest big trophy bucks on commercial hunts, we also harvested, we had an option for commercially harvesting cull bucks, an option for commercially harvesting management bucks, and and a lot of those yearling bucks would have later turned into at least cull bucks, right, at maturity or management bucks at maturity, for which we could have been getting some revenue back for their harvest that we didn't capture in this stuff in this study.

Dr. Bronson Strickland 48:49

Yeah, that's uh something we've uh talked about a lot too. The other the the other side of of this from a like a population dynamics perspective is even if this worked, one of the results of a very intense culling program is you're gonna end up with fewer deer. So the the the more intensive you are, you know, at one or two or three, I mean, the the fewer mature bucks you're gonna have. Now, if the culling worked, you might end up with, you know, some really big mature bucks, but you just have to recognize that you're gonna end up with fewer bucks by doing this. And so it's it's kind of the the worst of these outcomes because it didn't work. The culling didn't work, there was no genetic improvement, and you have less bucks at maturity. So it was a a negative double whammy for you and the King Ranch. Yeah, yeah.

Moriah Boggess 49:47

And then you think about in the Southeast, where people a lot of people apply this method, they might be culling their two-year-olds and three-year-olds. Four-year-olds might be the only age class they're truly protecting because then they're harvesting at five and a half. But then, so then I mean, think about that. You're at you're you're harvesting a decent amount of your immature bucks. You're harvesting bucks when they get to maturity, but then add another layer on there, which is the mistakes when you have that 150-inch three-year-old. I mean, records show like that is the most likely deer to get for a mistake to happen on. Because when he walks out on somebody, they're thinking, there's no way he's a three-year-old. You know, I you they start to make the case in their mind that, you know, or they just they flat out say, if I don't shoot it, the neighbor will. And so you end up in the situation where people are killing the poor quality bucks, they're killing the high quality bucks young, and then they're killing the middle of the road bucks some at maturity. And what does that sound like? Uh like you said, like the absolute worst situation possible. Mick, that's not what you all were were doing in this study or setting out to do, but that's what I that's what I see happening so much in the real world is that there's always an excuse to shoot a deer. And when you're making mistakes on the best deer, then that kind of shoots yourself in the foot for everything else you're doing.

Dr. Mickey Hellickson 51:10

One other, one other interesting anecdote that occurred during this study, or a little sidebar, is that the very biggest buck we captured on the treatment area during the course of the study, we first captured him as a as a buck that we estimated at two years old by tooth wear. He had double drop times, I forget 13, 14 points as a two-year-old. Growth scored 128 as a two-year-old. And so obviously he was, he he didn't qualify as a cull and he was put off limits. And that was the first year we caught him was the second year of the study. Okay, so he was a yearly in the first year, and we didn't end up catching him. But the second year we caught him, he was two. We managed to recapture him three years in a row. So we recaptured him at three, again at four, and again at five. And by the time he was five, he swelled up to a 199-inch double drop time monster buck that lived in the treatment area where we effectively removed 125 coals from around him within that 9,500 acre treatment area, creating the best scenario possible. Our biggest buck now has 125 bucks removed from his neighborhood. And we proved this is a good story, bad story kind of thing, we proved that he was a contributor to DNA because we found a doe that he successfully bred. That's the good news. The bad news is the way we found that doe is we harvested her in February, and her fetuses were his fetuses, right? And so we confirmed that he was breeding, but but we killed his offspring when we harvested that pregnant doe. And of course, he could have uh hopefully he had he had other offspring, right? But on average they have 1.6. So that is I guess that for whatever that's worth, but it it's interesting what happened there.

Teaser for Part 2 — Enclosed Populations & the Comanche Ranch

Dr. Bronson Strickland 53:09

Yeah, that that is. That's a great story and kind of a a great way to uh I guess wrap it up as well is there you go. You've got uh you say in the 190s, Mick?

Dr. Mickey Hellickson 53:21

He grossed toward 199 and change, so most people would round that up to an even 200 inches, right?

Dr. Bronson Strickland 53:27

So and and you removed a great deal of competition in terms of other bucks and breeding opportunities. You you you set everything up there for your biggest guy to have a whole bunch of breeding opportunities, and I'm sure he did beyond the doe that y'all y'all killed that was carrying his offspring. I'm sure there was others. And even with that, even with such a big sire in the population you saw in the previous graphs, it didn't change anything. Right. Yeah, no, no genetic change at all. Well, thanks, Mick, for first of all, thanks for the study and all the the years that you, your co-authors, King Ranch, Texas AM, Kingsville, etc., Texas Parks and Wildlife, all the work they put in. I think it was very well done. I think you you controlled everything that you could control, practically speaking, in in a free-ranging environment. The next phase or part two of this kind of culling, reviewing this culling program, we're gonna look at the next step, and that was working with enclosed populations. So with the King Ranch study, we saw the big influence of dispersal, bucks moving on and on and off the property, yearling buck dispersal impacts that could have had. What happens if we remove that and have enclosed populations? Also, with the next phase, the Comanche Ranch study, also looking at the removal of deer or the culling of those bucks before the breeding season, and also reducing the harvest mistakes. And so those bucks were captured, they were aged, antlers were measured, and so it wasn't a hunter pulling the trigger and maybe making a mistake, it was aging the deer and measuring the antlers and making the culling decision there. So controlling a few more things with phase two of this. So we'll get to that next time, but thank you both for your time. I appreciate it and had a great time talking about about the past, Mick. Thanks so much.

Dr. Mickey Hellickson 55:35

Thank you very much, Bronson. Great to see you. Thank you. Honored to be on your podcast, and thank you.

Outro

Moriah Boggess 55:41

Thanks for listening to the Wildlife Investments Podcast. For more information on these topics or to see some of the projects our team is working on, follow us on Instagram and Facebook at Wildlife Investments, or visit wildlifeinvestments.com.