Trophy Potential

Throughout the years, it has been difficult to determine trophy hotspots outside of areas that claimed to specifically manage for older age classes of animals. Trophy hunters were told to peruse the B&C or P&Y record books to uncover areas that have produced well in the past. However, the record books generally only recorded a county of kill, which won’t always be useful in determining an individual unit. Additionally, those kills may have been 100 years old, or so few and far between, that the records are virtually useless for determining places that routinely produce older animals. Also, keep in mind that a Boone and Crockett class animal is a freak of nature, whose antlers far exceed anything else in his age class.
Age, genetics and nutrition all play a role in producing large antlers, but age is the single most important factor. There is currently no practical way to determine the genetic potential in an area, and nutrition is usually sufficient in a mild year to come close to maximizing an animal’s antler growth for his age class.
However, at WesternHuntingData.com, we have devised two statistics to help you determine which areas have the greatest potential for older age classed animals. One of the statistics in our data sets shows the % of male animals harvested yearly. Obviously, harvesting a lower % of male animals increases the likelihood of allowing bucks or bulls to live an additional year, thereby growing larger antlers. Comparing between units to see which ones kill a smaller % of males is primarily how the statistic was designed, but can you use those statistics to determine an age class of animals to expect to be able to harvest? YES! Here’s how:
Let’s pick on my favorite unit to bash, unit 12 in Colorado, the most popular of the famed Flat Tops units. Unit 12 is part of a Data Analysis Unit where 45% of the available bulls are harvested yearly. Think about that, spikes aren’t generally legal, so hunters are harvesting over 45% of the bulls age two and older (spikes are almost always yearlings). Since spikes aren’t legal, that 45% bull harvest is a lot of pressure on the two and older class. So what’s the chance of harvesting a 3 year old bull? You have to make some assumptions here, but let’s assume a typical 40 calf: 100 cow ratio, with half of those calves being bulls, all of whom grow up to be spikes the following year. Now, in a unit whose pre season (not postseason) sex ratio is 40 bulls: 100 cows, it could be that nearly half of the bulls available are spike antlered yearlings. So, a 45% bull harvest, could be more like a 90% harvest of bulls age 2 and up if half of the bulls are spikes. The chance of surviving past age 2 is about 10%! Yikes. So since your typical 2 year old is a raghorn 3x4, 4x4 or maybe 5x5, and most three year olds are 5x5s or skinny 6x6s, what’s the chance of finding mature 6x6 5 year old bull? Nearly impossible, but let’s try to do the math. If a bull has about a 10% chance of survival from age 2 and on, to make it to hunting season of age 5, we multiply 10%(odds of making to age 3)x10%(to age 4)x10% (to age 5)=0.001, or 0.1%. That’s 1 in 1,000 bulls.
HOWEVER, this isn’t the whole story. These are the odds for the entire DAU (11,12,13,23,24,25,26,33,34,231,211,etc), not just unit 12. There is a lot of elk on private land that never ventures onto public ground, so maybe on those properties there is a 10% chance of making it to 3 years old or older. Not in unit 12. By applying the elk density to just the public land (which is likely higher than the entire DAU, so these are conservative estimates), and then extrapolating the number of available bulls, that 90% bull harvest jumps dramatically. You’re now looking at 288% of the extrapolated number of bulls being harvested (this is what we call the public pressure index). Of course they aren’t killing 288% of the bulls, but this number is useful in comparing other units. More than likely, private land harvest is having a significant impact on the total number of bulls harvested, thereby inflating the success rate. This number also shows that hunters are likely killing a heck of a lot higher % of bull elk on public land than on neighboring private lands. So in reality, the chance of finding a bull over 2 years old is almost impossible on public land. Compare this to unit 10, a famous trophy unit, not far from unit 12. The DAU% bull harvest is just 3% and the public pressure index is virtually identical (0.0477 or 4.77%), suggesting the vast majority of these elk are harvested on public lands. Well that’s a trophy unit, and it takes 13 resident preference points to hunt there. Would you believe that there are OTC units in Colorado that harvest less than 20% (and some less than 10%) of the available bulls in the DAU? And they clearly aren’t coming just off of private land when they have public pressure indices that are the same as or better than trophy units like 40 and 76 (but not quite as good as 10). So, in a unit where 20% of the bulls are being harvested on public land, what’s the chance of finding a 5 year old bull? Assuming no natural mortality and no spike harvest, the odds of the bull you found being 5 or is nearly 22%. That’s not bad at all. These units are out there and they are available over the counter. Nobody talks about them for a reason.
Similar things apply in every state. In some states (Montana for instance), spikes are legal with the bull tags in some units, so there is far less pressure on the older bulls. There are Oregon general season tags for units where less than 10% of the bulls are harvested yearly. In Idaho, a handful of units harvest less than 10% of the bulls, and many general units harvest under 20% of the bulls.
Now for deer, especially in places where spikes are legal, the odds of making it to an older age group change slightly. If yearlings are legal, we have to apply these mortality rates to yearlings. And of course, natural mortality is much higher with deer. Now let’s pick on unit 52 in Colorado. The % of bucks harvested in that DAU (includes 521 and others) is just 21%. So to make it to age two, you are looking at 100-21=79%. Well that’s pretty good, but we all dream of 4x4s, not big forkhorns. So to make it to age 3, assuming no natural mortality, multiply .79x.79=53%. Once again not bad, thank goodness for all deer tags being controlled in Colorado. But we forget about the public pressure index, which suggests closer to 80% of the available public land bucks are harvested. So in unit 52, you might be seeing all sorts of great deer on the ranch land as you drive up into the national forest, but all of a sudden, the big deer are gone, and you are only seeing little forkhorns. That’s because to make it to just to age two, that little buck’s odds are just .2x.2=.04, or 4%, not including natural mortality. So there is a chance of seeing a two year old, but it’s pretty slim.
So think about these things when selecting a unit if trophy potential has any meaning to you. Be honest with yourself, if you won’t be happy settling for a raghorn or forkhorn, whose meat is certainly delicious, don’t shoot it. Leave that animal to someone who would be happy with him. And if all you are seeing are little bucks, and you aren’t happy with them, you’re probably in the wrong unit.
Good luck this season