Using Sheds to Estimate Buck Numbers
 

I've been working on a new idea, and the math is going to get a little heavy. (So if math ain't your strong suit you're gonna get lost here. I'm half-lost myself. Just a warning, no hard feelings!)

I think it is possible to estimate with great precision the number of bucks on your spread by the sheds you find. The key question in the equation is how many matched sets you find. Let's get to it.

THE THEORY

Let's make two big assumptions to illustrate the equation, then later we'll try to deal with the real world and how those assumptions break down. Our first assumption is that all antlers are equally easy to find, and our second assumption is that the finding of a second antler (i.e. one that completes a matched pair) is an independent event from the finding of the first antler of the pair. remember the definitions; "first antler" is any unmatched shed found for a particular buck, "second antler" is any antler that completes a matched set for a particular buck.

We can find x, where x is the total number of sheds in your search area, with the following equation: # of second antlers/ # of first antlers = Total # of first and second antlers/x. Simply put, the percentage of matches you make from your first antlers represents the percentage of all sheds out there that you are actually finding. For example, suppose I found 9 sheds on my hunting lease this spring, and had two matched pairs among those 9. So, I have 7 first antlers and 2 second antlers. The equation becomes 2/7 = 9/x. Solving for x, we get x=31.5. I would predict that I have 31.5 antlers out on my lease. I found 9, so there's about 21 or 22 more still laying out there somewhere. I could also use this number to project that 15.75 bucks are using my lease in the spring.

THE REAL WORLD (with minimal apologies to MTV)

Of course assumptions break down when we enter the real world. The first assumption is that all antlers are equally easy to find. Of course this is not really true. One antler may be laying out in the open, and another may be stuck in a briar patch. Also, obviously a little forkie horn is going to be much more difficult to see than a BC bruiser shed. The first objection, that some antlers are better hidden than others should not be a concern for our equation, however, because this is a random factor. A big buck's shed is really no more or less likely to be hidden by terrain or vegetation than a small shed. But the second objection carries some weight. This factor is not random, yearling antlers are always going to be tougher to find than sheds off a 5 1/2 y.o. buck. If we lump all antlers together, we're going to get a distorted prediction.

The solution to this dilemma is to compare like to like. Ideally, we should calculate a different equation for each age class - one for 1 1/2 y.o. bucks, another for 2 1/2 y.o. bucks, and so on. Sample size being very imprtant to an accurate estimate, in the real world we would need to keep several years of data on this to attain an accurate picture. (I am starting a shed log book this year.)

The second assumption in my theory is the real sticker. Probably I don't have to argue too much to convince you that finding a second antler is not at all independent of having found the first antler. If you find a big ole shed, what do you do? You stop and start doing a grid search around that first antler, looking for the second antler. Unfortunately, this special effort blows the predictive equation all to hell. For the equation to work, the finding of a second antler must not be in any way the result of having found the first antler. Back to my example, where I found 7 first antlers and 2 second antlers, I should ask myself the following question about the second antlers: Would I have found that second antler even if I had never found the first antler in the the set? (Was the second antler laying fifty feet away smack in the middle of the trail I was following? Did I find it three weeks after I found the first antler? Or was it laying down in a hollow 90 degrees off my intended course, and I only found it because I started a grid search from the first antler?) If the answer is that, yes, I would have found the second antlers regardless, then the equation will hold. But if the answer is no, or some degree of maybe, we've got problems.

I believe this problem can be gotten around. Ask the question of any second antler: How likely is it I would have found this antler even if I had not found the first antler? Answer one of the following: likely, somewhat likely, somewhat unlikely, or unlikely. If the answer is likely score it as a second antler found. If somewhat likely, score it as 2/3 of a second antler. If somewhat unlikely, score it as 1/3 of a second antler. If unlikely, don't count it at all.

In closing, I could take the post by Carll on here titled "Sheds!!" and predict the total number of BC class sheds on his place. He has 5 first antlers and 4 second antlers. If the second antlers were completely independent finds, we would have 4/5 = 9/x, with x = 11.25. Carll would have to reflect on the circumstances of finding each of the four second antlers and tell us to what degree finding them was related to having found the first antler in order for us to fine tune the equation.

Anyhow, I invite any critiques or comments along two lines:

1) Is my math correct?

2)How do I make this equation more relevant to the real world? Can my assumptions be amended? Have I missed a key element?

RE: Using Sheds to Estimate Buck Numbers
 

The only way I see getting any kind of a number of bucks relative to the number of sheds is if you did a systematic sample of the hunting area. If you did one - 1/10th acre sample per acre and were lucky enough to find a few sheds in the sample areas you could assume the number of bucks. Thing is bucks do not stay in one area all the time due to changing food sources and of course the rut so the plot system would probably be only a way to spend a few hours in the woods............ I spend a lot of time in the woods cruising timber and it is very rare that I find a shed.

RE: Using Sheds to Estimate Buck Numbers
 

Weird, my math teacher told us something just like that. Your not a teacher, are you?

As for math, I lost ya half way through. But I think the only way to know the number of bucks on your land is to sit and watch 'em go by. at least thats how i think.

RE: Using Sheds to Estimate Buck Numbers
 

you know what they say when you ASSUME

RE: Using Sheds to Estimate Buck Numbers
 

I just hunt and add up the deer on the pile

RE: Using Sheds to Estimate Buck Numbers
 

Dirt....without beating around the bush cuz i don't feel like typing today, and at the sake of sounding rude which i apologize for in advance, your model is one of the stupidest things i have ever seen. you absolutely CANNOT count deer by shed antlers. IMPOSSIBLE. You may have an area that the deer winter in that is 5 acres in size and loaded with sheds that doesn't have a deer in it from april til december. on the flip, you may not find a single horn in an area that is loaded with deer in those times mentioned. deer travel GREAT distances is some circumstances to winter, and in almost every circumstance, they do not winter where they live the majority of the year. also....many many sheds are under water never to be found period...MANY. It's nice that your trying to figure things out, but the variables involved in this problem fluctuate far to much to even come up with a theory.

RE: Using Sheds to Estimate Buck Numbers
 

Actually, all of you were gentler on me than I expected. One thing I'm actually quite sure of is that this method can work.

The shed count I've laid out is simply another version of the classic capture-recapture method that is used all the time to estimate game populations. With this method, you capture as many critters as you can and tag them. Then, at a later date you recapture critters in the same area. This is exactly what the game departments are about when they ask you to return leg bands off game birds. Well, with my shed hunting idea, the "first antler" is the tag, and the "second antler" is the recapture event. Simple, really.

Timbercruiser, you've touched on one area I didn't include in the original post. Sample size, that is. You need to have at least 20, preferably 30 or more sheds in order to get an accurate prediction.

Livetohunt, no I'm not a teacher, but I do have a B.S. in wildlife management. (No, not that kind of b.s.!)

BobD, assumptions are an inescapable part of life. You see a lot of deer sign in an area, you set up a stand. You've assumed deer will be there again. You sit down in a chair, you assume it will hold your weight, right? Or do you stop each time and examine the chair minutely to insure that it can bear your weight? You start your car, you assume some mob guy didn't rig a bomb to your ignition. If we didn't assume things by the gross we'd never get anything accomplished in life. (By the way, next time some P.C.-type lectures you on stereotypes these same arguments can be adapted to a response. We simply must stereotype people and situations to get through our daily lives.)

Moosehornhunter, the winter range concern is one I actually aluded to, quite briefly, in my original post. I noted that the estimate you would get would be for how many bucks spent the winter/spring on the piece of land you're searching. It's going to depend on the specific region your in how many bucks stick around the rest of the year.

Anyhow, I'm just trying to shake up the field a little, get away from this brain-frying repetition of Do scent blocker suits work or not?, Is a .243 a good deer round?, and on and on and on. Then next month we can do it all over again, but that time we'll argue about 6 mm's instead of .243's.

RE: Using Sheds to Estimate Buck Numbers
 

You've got a novel concept there, Dirt, but I think in the real world it would be much more difficult to get accurate results, at least in some places, than using other methods. A spotlight survey is much easier and probably more accurately reflects the true number of deer. Mainly because the sample size would be much larger, theoretically making it more representative of the total population. It would also require a lot less man power. I'm not sure how many acres you would have to completely comb through to get a reasonable estimate.

One assumption your also making is that deer randomly access the entire property. This probably isn't accurate, as they will have favorite hangouts they frequent more often than others. They should then lose more antlers in this area, so your survey would have to encompass a large enough area to account for all that.

If you comb the area being surveyed thoroughly enough, you should be able to take care of your first assumption. Maybe your second with careful planning.

RE: Using Sheds to Estimate Buck Numbers
 

My theory is if you find lots of sheds then you probably have lots of bucks.

RE: Using Sheds to Estimate Buck Numbers
 

That reminds me of a tongue twister I know:

How many deer would a deer hunter have if a deer hunter could find antlers?

I know, corny as hell... but it's getting late!

RE: Using Sheds to Estimate Buck Numbers
 

Good points, North Texan. Spotlight counts might have some validity IF you've got a food source that draws the bulk of the deer nightly, and IF you've got roads that allow you to get beside those food sources. Neither IF applies to my neck o' the woods.

Certainly, deer do not use an area randomly, and to be purely scientific, one should randomly sample his/her entire property. Sadly, that ain't possible on "my" piece of land, which is about 100,000 acres of Forest Service land. A truly random search pattern would result in finding about 0.3 antlers per year! So I'm actually keying in on certain important terrain features where deer activity is higher. (At that, I've found 8 fresh sheds this spring, so I've got a couple more years of searching to go.)

I think my little method would be really ideal for a 40 to 160 acre tract of bedding cover.

RE: Using Sheds to Estimate Buck Numbers
 

If you have a food source that draws them specifically to that area in bulk, you really can't use it because it distorts the true numbers of deer on the property.

The spotlight survey does have its flaws, but it works pretty good around here. Although, the helicopter survey worked a little better and was probably a little more accurate.

RE: Using Sheds to Estimate Buck Numbers
 

interesting concept you have there Dirt2, I've been looking at it and I wouldn't buy it. I ran a little test of numbers on my own. I took your original 9 sheds, 2 matched pairs so you have
2/7 = 9/x solve X and get 31.5 sheds on your lease and a estimated 15.75 bucks. Now lets say you found an additional matched pair, instead of nine you found 10 sheds, so now the math goes to 3/7 = 10/x, you solve for X and get only 23.333 sheds on lease and 11.66 bucks on your lease. So now with just an additional matched shed you have 8.167 less sheds on your lease and 4 bucks less. Since I dont like the declining number, i find 8 sheds total with only 1 matched set, so I still have 7 first antlers and 1 second antler, i do the math 1/7 = 8/x and come up with 56 sheds on my lease and 28 bucks on it. As you can clearly see by simply finding an extra matched set decreases your bucks, or simply by not finding an extra match increases your odds. Also your equation would not work if you simply did not find the match to a shed because you cannot divide by Zero. my math if you found all 7 sheds plus match leaves to a total of 14 sheds on your lease, and 7 bucks roaming it. so depending on your shed hunting abilities if you find 1 match, you have 56 sheds, if you find 7 matches you have 14 sheds, that is a 42 shed difference. you decide if it works or not, neat theory though. ;) Maybe I dont understand your theory though, correct me if im wrong.

RE: Using Sheds to Estimate Buck Numbers
 

So how many did your neighbor find while trespassing, genius?

RE: Using Sheds to Estimate Buck Numbers
 

I dont know man... I see a lot of nice bucks every year when I'm hunting but have never found a shed. I have looked and looked and still havent found one. You say you need to find 20 to 30 sheds to have the equation work and tell me I have bucks living on my property. I can go bow hunting the first week in October and tell you there is a quite a few nice bucks there.

RE: Using Sheds to Estimate Buck Numbers
 

I just read Liv4Rut's post and he's got a huge point!! Just by finding one more shed it will through the numbers off by that much and in the opposite direction you would expect. I gotta agree with him!

RE: Using Sheds to Estimate Buck Numbers
 

Why not rent a plane for an hour and fly transects over the area before they drop their antlers. It's a lot more accurate. I'd have to agree about the sample size being to small. I seem to remember mark and recapture studies need very large sample sizes (more than 20 or 30)to be accurate. I just don't think that few antlers is enough to make reliable predictions. Besides, there's to many outside variables. Good idea for a thread though. Good to exercise the old thinker once in a while:eek:.

What's next? how about a model designed to predict where a buck is most likely to drop his antlers based on: seasonal variables (weather, rut intensity, time spent feeding/bedding), habitat selection (type of feed, distance to feed/bedding) and habitat type (fences/downfalls to jump, thickness of cover). Any volunteers to do the math on that one? I didn't think so;).

RE: Using Sheds to Estimate Buck Numbers
 

You are absolutely right, Liv4Rut, the sample size in my example is way too small. I would point out that I mentioned previously that you really need 30 or more sheds in the bag in order get a fairly reliable estimate. Take 30 sheds, with 5 matched sets among them. You get: 5/25 = 30/x; x = 150. Find one more match: 6/25 = 31/x; x = 129. So, you drop from 75 bucks to 65, still a drop but not by such a big percentage.

In the country right around my home, this would not work, because like some of you say about your areas, finding even one shed is a noteworthy accomplishment. But in the new area I'm scouting now, I'll have some pretty good numbers in a couple more years. So tune in in April 2007!