Posted By: dstrong
Re: Shot a spike...Question - 01/06/11 11:46 PM
in the early years i've shot my fair share of spikes... Through the years and education... My management practices have changed... If you shoot spikes you are preventing yourself from being able to harvest older and more mature bucks. Below is a publication that is very educational for all hunters and deer managers on the topic of spike and shooting them or not to shoot them... Take the time to read and it will certainly help put a lot in to perspective for all..
Spikes, The Debate Continues ..... Part 1
by Mickey W. Hellickson, Ph.D.
updated August 25, 2009
There is no other topic like the issue of spikes to spark a heated debate at deer camp. Everyone seems to have an opinion about spikes. And although much has been written about spikes, the controversy is far from resolved and seems even more heated today. Included in Part I of this three-part series, I will define what a spike is, explain the ongoing debate, and then examine the results of various penned studies that have been completed, including the results of a recent ground-breaking study by the Texas Parks and Wildlife Department.
What Is A Spike?
Let's all start on the same page by first defining what a spike buck is. Ninety-nine percent of the time a spike buck is a one-and-a-half year-old buck. It is extremely rare for a buck two-and-a-half years old or older to still have only two antler points. In fact, we have now captured over 2,000 wild bucks in south Texas, as part of various research projects at Texas A&M University-Kingsville, and we have yet to capture a spike buck older than one-and-a-half years old! Therefore, whenever someone is talking about spikes, they aretalking about yearling bucks.
Yearling bucks are the equivalent of a young teenager. They are just getting started in life and are still at least four years away from maturity. Their bodies are only about two-thirds developed. At this young age antler growth is much less important than body growth and development. Yearling bucks are also near the bottom of the buck dominance ladder or hierarchy. The only buck more subordinate than a yearling buck is a buck fawn.
The Shoot All Spikes Theory
The age old debate regarding spikes revolves around the question of whether or not to shoot them. There are two general opinions. One opinion centers on the theory that spike bucks are genetically inferior. People on this side of the debate believe that the only good spike is a dead spike. They feel that by culling spikes they are improving the genetics of the deer herd because dead spikes cannot breed and pass on their "inferior" genes to future populations.
A second reported benefit from harvesting spikes is that these bucks can no longer compete with other deer for limited resources. On average, a buck will consume nearly one ton of forage each year of its life. If spikes are genetically inferior, the quicker they can be removed from the population the better because the forage ‘saved’ by harvesting spikes increases the amount of nutrition available for remaining deer. According to this side of the debate, managers who advocate waiting until a buck is middle-aged or mature before culling, ‘lose’ nearly one ton of forage per year per cull buck for each additional year that they allow those cull bucks to live.
A third reason suggested for harvesting spikes is that they are very easy for hunters to identify in the field. In fact, even the most inexperienced hunters are able to count antler points. Because spikes can be accurately identified, very few harvest mistakes are likely to occur. This is not the case when hunters are left to try to determine whether a potential cull or management buck is middle-aged or mature.
Lastly, some who take this side of the debate argue that if it is necessary to shoot some bucks because the deer population is too high, why not shoot spikes? Obviously, the adult sex ratio would also have to be balanced, or skewed toward bucks, to advocate harvesting spikes as a reason to reduce deer density because the quickest and most effective way to reduce deer densities is to harvest does, not bucks.
The Don’t Shoot Any SpikesTheory
The opposing opinion centers on the theory that spikes are not necessarily genetically inferior. Instead, it is believed that many of these bucks are spikes because of a host of reasons that have nothing to do with genetics. Most of the non-genetic factors mentioned as causes for spiked antlers involve poor nutrition. Nutritional factors include: (1) poor habitat; (2) drought conditions; (3) spikes that were born to doe fawns or yearling does that were not as efficient at producing milk as older does; and (4) spikes that were born with one or two other siblings and therefore had to compete with their twin or the other two triplets for the dam’s (mother’s) milk. The irony of these last two factors is that excellent nutritional conditions are required for doe fawns to breed as fawns and for does to have twin or triplet fawns survive. However, the fawns that are produced in these situations likely suffer nutritionally.
One non-nutritional factor often mentioned as a cause for spiked antlers involves a strung out or late breeding season. The result is that some does are not bred until their second or third heat cycle, 30-60 days later than does bred on their first cycle. The fawns born to these late-bred does then hit the ground 30-60 days later in the summer and are often spike-antlered the following year as a result. A severely skewed adult sex ratio is one cause for late breeding.
As mentioned above however, excellent nutritional conditions are another cause for late breeding because when nutritional levels are high, a higher percentage of doe fawns breed as fawns. By nature, doe fawns do not reach puberty until later in the breeding season than adult does, so doe fawns that are bred as fawns will almost always be bred late in the breeding season. And they will almost always produce spike-antlered yearling offspring as a result.
The Shoot All Spikes Research
The scientific basis for the Shoot All Spikes theory is rooted in research conducted within the deer pens at the Kerr Wildlife Management Area near Hunt, Texas. Texas Parks and Wildlife Department biologists Donnie Harmel, Bill Armstrong, Donnie Frahls, and others have been conducting breeding studies at this facility since 1973. During early research, they found that in a penned situation, spikes were inferior to fork-antlered bucks with regards to body weight and antler size through age four-and-a-half. They also concluded that the incidence of spiked antlers was hereditary. A third conclusion was that body and antler sizes were also influenced by nutrition.
These same biologists recently completed another long-term study on spikes with very dramatic results. They categorized yearling bucks into 3 categories: (1) yearling bucks that were able to produce forked antlers regardless of nutritional condition; (2) yearling bucks that produced spiked antlers regardless of nutritional condition; and (3) ‘swing’ deer (the largest group), which were yearlings that produced forked antlers under good nutritional conditions and spiked antlers under poor nutritional conditions.
Over a nine-year period (1991-99), pedigreed yearling bucks were placed in individual pens with 8-16 does to create single sire herds. Each December, all buck fawn offspring were then placed on a limited 8% protein diet to simulate poor nutritional conditions. The following October, the 5-6 yearling bucks with the best antler characteristics (e.g., highest gross B&C score) were used as herd sires for the next breeding season. These 5-6 bucks, out of a group of 19-34 yearling bucks, were then isolated in individual pens with 8-16 does per pen. Females that produced spike-antlered offspring, or that were siblings to spike-antlered yearlings, were selectively removed from the study. All females seven years old or older were also selectively removed.
A total of 41 single-sire breeding herds produced 217 yearling bucks during the study. Of these yearlings, 135 (62%) produced antlers with 6 or more points, while 28 (13%) produced spiked antlers. The percentage of spike-antlered yearlings declined from 33% in 1992 to only 3% in 1999, even though these bucks were nutritionally stressed! An even more amazing outcome was the tremendous increase in the percentage of yearling bucks with 8 or more points, which increased from only 3% in 1992 to 48% in 1999. This is especially astounding considering that less than 1% of yearling bucks captured in the wild in south Texas have eight or more points! Body weights also increased significantly over the course of the study. For example, average body weights for yearling bucks with 8 or more antler points increased from 117 pounds during 1992 to 139 pounds during 1999.
As a result of the above, they suggest that culling is most effective when nutritional conditions are poor(i.e., hunting seasons that follow drought conditions during late winter through spring). According to the theory, during nutritionally stressful times, the “swing” deer grow spiked antlers and can then be identified as the true culls that they are and harvested.
The Don’t Shoot Any Spikes Research
The scientific backbone for the Don’t Shoot Any Spikes theory is based on another long-term penned deer study. This study was conducted by Dr. Harry Jacobson at Mississippi State University. His results indicated that antler size in yearling bucks was not genetically based but instead, was dependent upon the time of year the buck was born. He found that spikes, more often than not, had been born later in the summer than fork-antlered bucks. Dr. Jacobson also found that there were very few differences between these spikes and forked-antlered bucks when the bucks were all five-and-a-half years old or older.
A second study, based on data from the Mississippi State University deer herd, shed further light on this ongoing debate. Dr. Steve Lukefahr, at Texas A&M University-Kingsville, did not find any antler trait in yearling bucks that could be used to reliably predict antler sizes during later years. However, as bucks increased in age, their antler traits increased in how reliably they could be used to predict antler size during later years.
In addition, he found that the dam had more influence on yearling buck antler size than any other factor. As these yearling bucks moved into older age classes however, the dam’s influence became less and less important. Dr. Lukefahr concluded that it was best to select culls from the older age classes because inferior yearling bucks could not be accurately identified based on any antler trait. Obviously, these results directly conflict with the results from the Kerr Wildlife Management Area study.
Another study by Dr. Lukefahr was based on a computer simulation to determine the genetic effects different types of buck harvests would have on the deer herd after 100 generations of implementation (about 300 years). He looked at three common management strategies. The first management type simulated a harvest of 5% of the trophy bucks and 10% of the spikes. The second simulated a harvest where spikes were intensively removed. The third simulated a harvest where trophy bucks were intensively removed.
The first harvest type caused a small, short-term increase in number of antler points in yearling bucks. The second caused a small increase in antler points. And the third caused a small decrease in antler points. However, after 100 generations all three harvest types ended with yearling bucks all within one-half point of each other. In other words, none of the harvest strategies had any long-term effect on antler sizes!
Penned Study Conclusions
The compelling results of the Texas Parks and Wildlife Department’s Kerr Wildlife Management Area study clearly show that, in a penned situation where who breeds who can be chosen, yearling bucks with spiked antlers should not be allowed to breed, especially if the goal is to increase average antler sizes and body weights over time. If you are one of the many landowners with a scientific breeding permit and you are working with penned deer, it is hard to argue with their striking results.
Obviously, a small percentage of spike-antlered yearling bucks have the capacity to develop into trophy bucks at maturity. However, the majority of spikes will never develop trophy-sized antlers, so the best advice is to not allow these bucks to breed in your deer pens. In fact, you may want to duplicate the treatment used in the Texas Parks and Wildlife Department’s study and nutritionally stress your buck fawn offspring to determine which bucks should be selected as breed sires. It is also likely that the Mississippi State University study results are less applicable to south Texas because the late breeding that is common in Mississippi occurs less frequently in south Texas.
The bottom line however, is that the question of whether or not to shoot spikes in a wild or free-ranging situation still remains unanswered. Unfortunately, all of the above studies have one big disadvantage - they were all conducted with penned deer. Although penned deer studies have taught researchers volumes of information about deer, landowners and managers should be very cautious when trying to apply these results to wild, free-ranging deer herds.
Penned studies are not very applicable in the real world for the very reasons that a penned study design is chosen. In the pen, nutrition is controlled and who breeds who is also closely controlled. In the wild, managers have less influence over nutrition and even less influence over who breeds who. In addition, does obviously cannot be selectively removed based on their breeding history.
Another problem with penned studies relates to the effects of dominance on antler development. Although research is lacking, it has been suggested that dominant bucks, especially in penned situations, suppress antler growth in subordinate bucks. If a subordinate buck in a pen never reaches a dominant position, how do you know what his true genetic potential was? John Ozoga completed some interesting studies on the effects of density stress on deer in Michigan. He found that even when nutrition wasunlimited, antler sizes and fawn crops decreased once deer densities passed a certain threshold because of the effects of dominance and density stress.
The only way to finally settle the spike debate is to conduct similar research with deer in the wild. Part II in this three-part series will examine results of research conducted on deer in the wild and will highlight early results of ongoing research geared toward settling this age-old debate.
Spikes, The Debate Continues .... Part 2
by Mickey W. Hellickson, Ph. D. - updated September, 2009
In Part I of this series, I defined what a spike buck was and I explained what the ongoing debate is about. I also summarized the theories behind each of the two camps related to the question of whether or not to shoot spikes. Lastly, I examined the results of the various penned studies that have been completed in an effort to settle this debate.
Unfortunately, these studies have not addressed the question of whether or not to shoot spikes in a wild or free-ranging situation because of the inherent biases associated with studying penned deer. In penned situations, deer are forced to live in very close quarters with each other. The social interactions, density stress, and influences of dominance caused by this very unnatural situation may have large impacts on antler growth that may have affected the outcomes of these penned studies.
Another problem with past penned deer studies is that most of the selection abilities available with a penned deer herd are not possible with wild herds. Many penned studies involved some form of selection that was applied to the doe segment of the deer herd. In some situations, does were selectively removed if they had produced spike-antlered offspring, or if they were siblings to spikes. Obviously, in the wild, the breeding history of a doe is unknown, so this same selection cannot be applied in the field with wild deer herds.
Researchers conducting penned studies also often determined which bucks would get the chance to breed. Specific bucks would often be selected for their superior antler traits and then isolated in a pen with does that were also selected based on their breeding history. Obviously, in the wild this same control over who breeds who cannot be duplicated. Although inferior bucks can be intensively culled and removed from a wild deer herd, there is no way to insure that the largest of the remaining bucks do the breeding.
Lastly, in the wild, nutritional levels are also obviously much more difficult to control. Although an advantage of penned studies is that the effects of nutrition can be controlled, in the wild, this same control is not possible. Where nutritional levels are highly variable, such as is the case in south Texas, the effects of nutrition on antler size may swamp all evidence of any genetic effects.
It seems the only way to finally settle the spike debate is to conduct similar research with deer in the wild. Part II in this three-part series examines the results of research conducted on deer in the wild.
Percentage Of Spikes Is Highly Variable
During a 10-year period (1985-94) we randomly captured 491 wild bucks on a large, private ranch in south Texas. Sixty-one of these 491 bucks were yearlings. Twenty-four of these 61 yearlings were spikes (39%) indicating that, on average, over one-third of the yearling buck population in south Texas will be spike-antlered in any given year.
We have also found a huge amount of variability from one year to the next in the percentage of yearling bucks with spiked antlers in our deer captures. In 1985, none of the yearling bucks that we captured had spiked antlers, but in 1988, 50% were spikes. In 1991, only 17% of the yearling bucks were spikes, but the very next year in 1992, 90% of the yearlings were spikes. Obviously, with this much variability in the incidence of spikes, genetics is not the only factor influencing this trait - rainfall and nutrition play a very large role as well.
In 1992, when spikes made up 90% (9 out of 10) of the yearling bucks that we captured, it would have been disastrous to harvest all of these spikes because you would have removed 90% of your yearling age class! If you were to kill 90% of the yearling age class, you might as well sell the ranch or move to another lease because you will likely not have any mature bucks to hunt four to five years later.
High Natural Mortality
Is killing all spikes that bad, even if it represents an average of 40% of the bucks in that age class during any given year? It very well could be because so far we have only been talking about spikes that are killed by hunters. What about yearling bucks that die of natural causes?
During 1992-95, we captured and radio-collared 130 bucks. Of these 130 bucks, 20 were yearlings. We radio-tracked these bucks continuously after their capture to determine their survival rates outside of the hunting season.
None of these 20 yearlings were killed by hunters. One buck died within one month of being captured and was excluded because the capture itself may have caused its death. A second buck had its radio transmitter fail so that we could not track its survival. This buck was also excluded. An average of 39% (7 out of 18) of the remaining 18 yearling bucks died of natural causes within one year!
Although it is still not clear what affect hunting has on deer survival rates, we can at least assume that hunting is partially additive. This means that a portion of the spike harvest each year will be added to the 39% natural mortality rate. If hunting were totally additive than you may be in danger of losing an average of 80% of your yearling bucks each year by intensively culling spikes!
Older Bucks Die Too
Also, so far we still have not taken into account the natural mortality rates of older-aged bucks. Our research indicates that an average of 17% of 2.5-year-old bucks die each year of natural causes. Twenty percent of 3.5-year-old bucks die and 5% of 4.5-year-old bucks die of natural causes also.
What do all of these different percentages mean? Let's start with a population of 100, one-year-old bucks and look at their survival based on natural mortality alone. Only 61 of these bucks will survive to age two. Only 50 will survive to age three. Only 40 will survive to age four. And only 38 of the original 100 bucks will survive to age five without any bucks being removed by hunting.
On average then, 62% of all yearling bucks will die of natural causes before they reach maturity at age five! So, without killing even one spike buck, 62% of those yearling bucks will still die of natural causes before they reach five years of age. Why would anyone want to kill a yearling buck if they are interested in allowing the maximum number of bucks to reach the trophy age classes of five years old and older?
When Does Antler Size Peak?
We have very conclusive data when it comes to knowing when antler size peaks for bucks in south Texas. We have now randomly live-captured over 2,000 bucks from the wilds of south Texas. We have aged all of these bucks by tooth wear and measured all of the racks according to Boone and Crockett Club guidelines. On average, antler size and gross B&C score does not reach its maximum until a buck is at least six-and-a-half years old. In fact, many bucks do not peak in antler size until they are seven-and-a-half years old. Many of the body characteristics we have measured during past buck captures have also indicated that several body measurements do not peak until these same ages.
Clearly then, if you wish to allow bucks the opportunity to reach their full antler growth potential, they need to be allowed to live until the six-and-a-half and seven-and-a-half age classes. However, as noted above, the majority of bucks will die of natural causes before reaching these ages. Interestingly, the average gross B&C score of a six-and-a-half year old buck in south Texas is only 130 inches.
Is Rainfall (And Nutrition) More Important Than Genetics?
Rainfall may have more to do with the incidence of spikes than genetics. In south Texas rainfall, more than any other factor, determines antler size. Stuart Stedman, a private rancher and a very knowledgeable deer hunter, has discovered that gross Boone and Crockett Club (B&C) scores of mature bucks are very strongly correlated with the amount of rainfall during the month of April. He has compared gross B&C scores of hundreds of live-captured, wild bucks to the amount of rainfall at various times of the year. He found that as rainfall during the month of April increased, so did antler size.
In another study illuminating the importance of rainfall, Dr. David Hewitt of Texas A&M University-Kingsville, modeled the influences of rainfall on trophy buck production in south Texas. He found that April rainfall had an even greater influence on the number of trophy bucks in any given year than did fawn production and survival 6-10 years previous.
Yet another indicator that nutrition is more important than genetics is the amazingly low incidence of spikes in yearling bucks killed in the Midwest. I am originally from Iowa. I have hunted deer in the Midwest for the past 25 years and although I have seen hundreds of dead yearling bucks, I have neverseen a dead spike buck in Iowa. The Midwest is the corn and soybean capital of the U.S. Deer in these states live year around (virtually) in a huge food plot. Obviously, nutrition can override any negative effect that genetics may have on antler growth.
The Latest Research On Wild Bucks
Clearly, caution should be used when determining whether or not to shoot spikes because of the potentially large impacts this may have on the number of mature bucks in future years. However, the above research does not specifically address whether spikes are inferior to fork-antlered yearling bucks in the wild.
In order to get at this very pertinent question, Dr. Fred Bryant, Dr. David Hewitt, and I initiated the South Texas Buck Capture Project in 1998. This long-term, large-scale project involves the helicopter-net gun capture of 60-75 bucks and fawns annually on each of six different ranches. Since 1998, we have randomly captured anywhere from 360 to 450 wild bucks and fawns each year!
During the initial year of the project, we targeted yearling bucks in order to have a large sample size of known-aged bucks on these ranches during later years. This design has allowed us to recapture a large number of these same yearling bucks at older ages. More importantly, these recapture data have allowed us to directly compare spike-antlered yearling bucks to fork-antlered yearling bucks at older ages.
After the first three years of the project, 50 yearling bucks (27 spikes and 23 fork antlered) had been recaptured at two-and-a-half years of age. Statistical analysis indicated that fork-antlered yearling bucks had significantly wider inside spreads, larger basal circumferences, longer main beams, more antler points, and higher gross B&C scores than spike-antlered yearling bucks. In fact, in nearly every category we measured, the fork-antlered yearling bucks were significantly larger than the spike-antlered yearlings. Gross B&C scores for the spike pool averaged 71 inches compared to an average of 85 inches for the fork-antlered pool.
An additional 25 yearling bucks (18 spikes and 7 fork antlered) have been recaptured at three-and-a-half years of age. Statistical analysis indicated that fork-antlered yearlings had significantly higher gross B&C scores and more antler points than the spike-antlered yearlings at this age. Gross B&C scores for the spike pool averaged 97 inches compared to an average of 128 inches for the fork-antlered pool.
Due to the small sample size however, the other characteristics we measured were not significantly different. At these relatively small sample sizes, differences between ranches also affected the outcome of the comparisons. However, by the conclusion of the study, we expect to have sufficient sample sizes to identify any true differences between the two classes of yearling bucks at all age classes from two-and-a-half through five-and-a-half years of age.
Although these results are interesting and the early indication is that spikes are in fact inferior to fork-antlered yearling bucks, we still do not yet have an answer to the age-old question because these spikes may still ‘catch-up’ to the fork-antlered bucks by maturity. Therefore, the study will be continued for several more years to allow these same bucks time to reach maturity. In the very near future, we will finally know if spikes are inferior to fork-antlered yearling bucks in the wild.
In Part III of this three-part series, I will attempt to summarize all of this research into harvest recommendations that you can use on your property.
Spikes! The Debate Continues ... Part 3
Mickey W. Hellickson, Ph.D.
In Part I of this series I defined what a spike buck was and I explained what the ongoing debate is about. I also summarized the theories behind each of the two camps related to the question of whether or not to shoot spikes. Lastly, I examined the results of the various penned studies that have been completed in an effort to settle this debate.
In Part II of this series, I examined the results of several studies that have been completed during recent years on wild bucks in south Texas. It was important to discuss these additional studies because of the inherent biases associated with penned deer studies. Finally, in the third and final installment of this series, I will attempt to summarize all of this research into harvest recommendations that you can use on your property.
Deer Management Goals
Of course, the whole debate about whether or not to shoot spike bucks all depends on your specific deer management goals. If antler size is not important and your goal is to maximize the harvest of bucks of any age on your property, then you should shoot spikes. The reason you should shoot spikes is because a certain percentage of the spikes you don’t shoot will die of natural causes anyway, thereby reducing the pool of bucks you can potentially harvest. The only way to maximize the buck harvest under this scenario is to shoot every buck you encounter when it is encountered. Otherwise, some of those passed-up bucks will die of natural causes and won’t be available for harvest.
If your goal is to manage for maximum numbers of bucks two-and-a-half years old and older, then you should not shoot any spikes, even if they are later found to be genetically inferior. Many landowners and managers in the southeastern U.S., who are managing under Quality Deer Management guidelines fit into this category. In this situation, every spike-antlered yearling buck that you harvest results in one less buck that has the potential to make it to the pool of bucks two-and-a-half years old and older. Obviously, you cannot maximize the pool of two-and-a-half year-old bucks by shooting bucks before they reach this age.
If your goal is to manage for maximum numbers of mature bucks that are five-and-a-half years old and older, then you should not shoot any spikes as well. Under this scenario, a surprisingly low number of bucks will make it to maturity without any hunting at all. In fact, as was explained in Part II, an average of 62% of yearling bucks will die of natural, non-hunting-related causes by age five-and-a-half. Once again, any spike-antlered buck that you harvest results in one less buck that has the potential to make it to this magical age.
If you are involved in a commercial hunting operation and your goal is to maximize the economic return from your deer herd, then you should not shoot any spikes. No matter where you are in the U.S., a middle-aged or mature buck is always going to be worth more to the hunter and the landowner than a spike-antlered yearling buck. In fact, it’s doubtful you would be able to find many hunters willing to pay anything for a commercial hunt so that they could harvest a spike.
As explained in Part II, every single one of the yearling spikes that you let live to age two-and-a-half will develop a fork-antlered rack and will therefore be more valuable. Once again, after capturing over 2,000 wild bucks in south Texas, we have yet to capture a buck two-and-a-half years old or older with only two antler points. In the wilds of south Texas, spikes always
develop into fork-antlered bucks at older ages. In fact, spikes gross-score an average of about 70 inches at two-and-a-half years of age and around 100 inches at three-and-a-half years of age. By maturity, the majority of these spikes will develop into 120 to 140-class bucks. Bucks in this category are now much more valuable than either spikes or middle-aged bucks.
In fact, after measuring the antlers of over 2,000 wild bucks, we have determined that the average gross B&C score of a mature buck in south Texas is 130 inches. Which buck would you rather shoot and, which buck would you rather give your son or a guest the opportunity to shoot? I do not know anyone who would rather shoot a yearling spike when given the choice to shoot a mature, 130-class, eight point!
If your goal is to maximize antler size, while also maximizing economic return, then you still should not shoot spikes. Under this management scenario, where the adult sex ratios are balanced and the age structure in the buck portion of the herd is also balanced, very few young bucks will have the opportunity to breed does. Thus, whether they are inferior or not, they really don't have a chance to pass on their genes until they move up the pecking order as they mature.
Recent research has shed new light on the question of ‘who is breeding who’ and reinforces the idea that young bucks do very little breeding. Randy DeYoung, a Ph.D. candidate at Mississippi State University, used DNA collected from 435 deer to determine the paternity (e.g., sire) for 109 fawns. All of this DNA was collected from deer within a 3,200-acre fenced property in Oklahoma that is managed under Quality Deer Management guidelines. Under this management scheme, the goal is to reduce the harvest of young bucks in order to increase the number of middle-aged bucks in the population.
Randy discovered that bucks three-and-a-half years old or older sired a disproportionate number of fawns (Table 1). These older-aged bucks sired 64% of the offspring even though they only made-up 30% of the buck population. He also found that the minimum lifetime reproductive success was very low for the majority of successful bucks. The median number of fawns sired by any buck was one and the median age at first reproductive success was two-and-a-half years of age. The total number of fawns sired by individual bucks in his study ranged from one to nine, while one buck managed to sire at least six fawns in a single year. A minimum of 47 different bucks successfully bred and produced offspring. Finally, Randy reported that less than 20% of bucks achieved reproductive success in any single year.
Remember that this property was managed under Quality Deer Management guidelines. It is likely that even fewer young bucks would have the opportunity to breed on properties managed under trophy management guidelines, where upwards of 45% of the buck population may be mature and five-and-a-half years old or older.
Obviously, if increasing economic return is also a goal, landowners should not harvest spikes because these same bucks will be worth a lot more money at an older age when they are fork antlered. If spikes are not going to negatively impact the genetics of the deer herd because they are unlikely to successfully breed, then they should be allowed to live until they reach an age where hunters are interested in paying for the opportunity to harvest them.
Things become more clouded however, if your goal is simply to maximize antler size. Under this management goal, the recommendation is more dependent on economics and property size as it relates to the ‘corral continuum.’
The ‘Corral Continuum’
I first learned of the ‘corral continuum’ concept from Stuart Stedman, a deer fanatic and a private rancher in south Texas. He used the concept to describe how deer management intensity varies across a continuum. At the left-end of the continuum, you find very large, low-fenced ranches where intensive deer management is cost prohibitive for all but the very wealthiest of landowners. At the opposite end of the continuum, on the far right, you find the very small acreage, high-fenced, deer-pen situations. Where your property sits on this continuum determines whether or not you should shoot spikes.
If your property sits at the left end of this continuum, you should not harvest spikes. On large, low-fenced ranches it would be extremely difficult to ever harvest enough spikes to insure that the very best bucks within the yearling age class did the majority of the breeding. In the Kerr Wildlife Management Area study, they hand selected the best 15-30% of the yearling bucks produced each year as breed sires. To duplicate this in the wild, 70-85% of your yearling bucks would have to be harvested each year to insure that they did not breed. This large of a yearling buck harvest is unrealistic on very large properties.
The 825,000-acre King Ranch is an extreme example of a property that sits at the left end of this continuum. In the case of the King Ranch, where deer densities average one deer per 30 acres by raw count (actual numbers are likely three times this amount), adult sex ratios average about two does per buck, and fall fawn crops average around 30 fawns per 100 does, there are an estimated 7,500 to 10,000 yearling bucks on the ranch in any given year. As we learned in Part II, an average of 40% of these yearling bucks will be spike-antlered. Therefore, hunters would have to harvest somewhere in the neighborhood of 3,000 to 4,000 spikes each year. However, this level of harvest still would not insure that the best 15-30% of the yearling age class did the breeding, an additional 2,500-5,000 yearling bucks would also need to be harvested each year to accomplish this!
On large, low-fenced properties, it is also impossible to selectively remove inferior does. In the Kerr Wildlife Management Area study, the best yearling bucks were isolated in individual pens with 8-16 does. Adult females that had produced spike-antlered offspring, or were a sibling to a spike, were selectively removed. How is this same selection from the doe segment of the herd possible in the wild, especially on large properties?
One option for selecting inferior does on smaller properties is to selectively harvest older-aged does because these are the does that are least likely to have been produced from the ‘superior’ bucks that are left in the population to do the breeding. Although overly mature does may be recognizable, it would be extremely difficult to accurately harvest a sufficient number of older-aged does to make an impact.
As mentioned, small-acreage, high-fenced ranches sit at the opposite end of this continuum. Ranches under this scenario, much more closely match the situation at the Kerr Wildlife Management Area deer pens, where they have shown conclusively that it is advantageous to cull spikes. In these situations, where nutrition and who breeds who can be more easily controlled, the recommendation is to shoot spikes. Obviously, the smaller the property, the more control the landowner has over nutrition and which deer do the breeding. As you move away from the deer pen situation, or corral however, the culling of spikes becomes less and less likely to be beneficial.
Hopefully, this three-part series has shed new light on the spike buck controversy. Obviously, the question of whether or not to shoot bucks varies according to management goals, economics, and property size. Also, the question of whether or not spikes in the wild are inferior is still unanswered. In the future, after our South Texas Buck Capture Project has been completed, even fewer questions will remain when it comes to making the decision of whether or not to shoot spikes.
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