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Long Term Harvest Rates

Written by: Mark Richman

When I first started using the percentage of available bucks and bulls being harvested as a trophy potential index a few years ago, I was shocked to find units that would rival places with national reputations.  However, I was a taking a one year snapshot and did not know whether those units were just occasionally “enjoying” a bad harvest year or if the numbers were truly indicative of their potential.  So I finally decided to finally take longer term look at Colorado’s trophy potential by examining the past 7 year’s worth of harvests.  I may expand this to other states if you guys like it.  If you don’t know what to do with the numbers, or what they mean, that’s what this article and the others we’ve posted on the site are about.

People who are new to my data often confuse my trophy potential index with a success rate.  The percentage of bucks or bulls being harvested is NOT a success rate.  A success rate is simply the number of animals harvested divided by the number of hunters.  A lot of things affect success rates and I wrote about some of those variables last year.  You can find that article on the website, it’s entitled Variables of Success. 

Anyway, what I’m talking about here is a way of determining units that will have older age classes of animals.  Over the past few years, I had been using a one year look at harvest rates.  When I tried to project survival odds using that single year’s worth of harvest, it could be heavily distorted by a good or bad harvest year.  For instance, back in 2007, the DAU that makes up units 15 and 27 showed an 8% bull harvest.  That’s as good as some of the best trophy units in Colorado.  However, 2007 was just an unusually low harvest rate.  More typical were years where 25 to 35% of the bulls were harvested, which is about average for Colorado. 

Along those same lines, unit 40, a trophy unit showed a 22% bull harvest in 2007, which is barely better a run of the mill unit, indicating the unit wouldn’t be worth using your preference points.

One last example:  unit 1.  Before I began studying the data to this extent, I thought unit 1 was supposed to be a trophy unit.  The success rates were on par with units 10, 2 or 201, and it required similar numbers of preference points, so why wouldn’t I think it’s a trophy unit?  Well, that’s probably the thinking of dang near everyone else.  All units will occasionally produce an older bull, as even the most heavily hunted units won’t kill every bull every year.  So when you hear of a 320 inch bull in unit 1, you’d think, “Well, of course, it’s a trophy unit”.  I got news for you:  Unit 1 is not a trophy unit.  The Colorado Division of Wildlife manages it as a crowd controlled unit, not a quality unit and the average bull harvest rate is over 30%.  But that’s not all, two out of the past four years had harvest rates over 50%!  Is that where you’d want to spend your 12 points for a muzzleloader hunt?

So how do we apply this information towards trying to determine what age class of bulls are available?  To give a more practical use for the data, other than a number with which to compare other units, I tried to determine the odds of an individual bull surviving 7 years.  No, the calculations do not factor in natural mortality nor do they factor in antler restrictions or other forms of selective harvest.  We just have to accept that those factors introduce far too many unknowns into the equation.

So, based on the present numbers, there’s at least 14 Colorado DAUs where a bull has a better than 10% chance of living 7 years, and some of those are OTC areas.  If you’re anything like me, you understand that it’s incredibly difficult to kill those older bulls, but I at least want to feel like they are out there.  In some of the most heavily hunted units in the state, I can’t even fool myself into thinking that a mature bull is lurking somewhere in the woods.  In places like unit 4, where the average bull harvest rate these past 7 years is over 40%, the chance of a bull surviving 7 years is just 1.8%.  To me, that may as well be 1 in 1,000.  You’re not going to look over 100 bulls before making a harvest decision, but in a low pressure unit with enough time to hunt, you may be able to look over 5 to 10 bulls.  Every one of those OTC units are fairly low pressure with plenty of wilderness.  Combine that low pressure, with fairly low success rates (if you’re read some of the other things I’ve written, it shouldn’t be news to you that wilderness heavy units tend to be low success units), and you’ve got a recipe for older bulls.

Everyone prioritizes things differently, but if you want to at least know there are older bucks or bulls out there in the woods with you, take a look at the Long Term Harvest Rates in the latest version of the Colorado data rankings.  Sure, I’ll shoot raghorns and the occasional forky, but I don’t dream of shooting young bulls. When I’m planning hunts I want to know there’s an older bull somewhere on that mountain.  It’s great to hear even young bulls trying to fire off their squeaky little whistles, but once you’ve heard that deep, throaty roar of a bugle that only an older bull can make, it’s just not the same.  Those bugles that feel like they are rattling your tent are what I want to hear when I’m a day’s march into a wilderness area.   Or you can delude yourself into thinking there are older bulls in the Flat Tops or Bear’s Ears and their reputation for raghorns are unfounded.



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