Buck To Doe Ratios

Before I start the major subject of this post I would like to say that I strongly support and believe in QDMA and the approach of Quality Deer Management, even though what follows may not appear that way.

If you spend much time reading hunting magazines, watching hunting shows, or talking to other hunters the subject of buck to doe ratios is something that everyone concerned with management is talking about. Most hunters, and until recently myself included, believe that buck to doe ratios were severly skewed towards females. I personally would have put the ratio where I hunt at 1 antlered buck to 8 or 10 does. And for this reason my philosophy was "shoot every doe that you legally can". While I still believe in shooting at least as many females as males, I no longer believe in the idea of badly skewed buck to doe ratios. Let me explain...

I recently read an article in Deer and Deer Hunting Magazine that I had to read about 5 times and I still didn't believe what the author had written, until I did the math. Basically the author was saying that antlered buck to adult doe ratios could not be more than 1 antlered buck to 3 adult does. The author, Jim Slinsky, was citing the work of noted deer researcher C. W. (Bill) Severinghaus.

The first time I read this I thought this guy must me nuts and I didn't even finish the article. Later I picked it up and read it through. Then I read it a few more times and decided to prove him wrong. I set up an excel spreadsheet to do the math and was astonished at what I found. My imaginary deer herd started out with 300 deer: 100 adult bucks, 100 adult does, and 100 fawns (50 buck fawns and 50 doe fawns because when fawns are born basically half will be males, half females). I decided that in my imaginary herd, every year I would kill 90% of adult bucks, no does or fawns would ever die, only adult bucks. I also determined that every adult doe would give birth to 1 fawn every year and the doe fawns would also be bred and have 1 fawn every year. I thought this would surely show antlered buck to doe ratios to be severly skewed, but I was wrong!! I ran this scenario for a 20 year period and the antlered buck to adult doe ratio NEVER went to more than 1 antlered buck to 2.8 adult does before hunting season in any year. Even if I showed the ratio as antlered bucks to antlerless deer (which would include all fawns) the ratio NEVER gets higher than 1 antlered buck to 5.6 antlerless deer before hunting season.

So I was wrong!! I cannot see a way that mathematically there can possibly be sex ratios of more than 1 adult buck to 3 adult does prior to any hunting season which goes against everything I previously thought to be true. However, what is severly skewed is buck age structure. In an area like my imaginary deer herd, the vast majority of adult bucks will only be 1 1/2 years old, not a very good place to hunt if you are wanting to kill mature bucks!!

While I still believe in killing does to keep overall herd numbers in check, getting sex ratios in line is no longer my concern. If you think I am wrong/crazy run the numbers yourself, or I will be glad to send you my spreasheet, or post it here if I can figure out how. If you can prove these numbers wrong please let me know, I have tried several ways to make the numbers be what I thought they should be but I couldn't change nature.

Very interesting Bone. Yes you can show your excel sheet. Well..Actually i would have to se tup a page for it. But thats simple. If you would like to send me the file I can do it! Go here Upload File
After it has been uploaded you will be given a download link. Just copy and paste the link in your post. Post back to me and I'll make a page. I would be interested in seeing myself. I'll make a page for it where members can view it. Great Job!

http://www.egupload.net/download.php?file=133714363-Deer_Sex_Ratios.xls

Boss Man, here is the link to my spreadsheets. The first sheet starts with equal numbers of adult bucks, adult does, and fawns and more importantly, the herd has good fawn recruitment every year. The second sheet is the same with the exception of starting with a 1 to 8 adult buck to doe ratio. This sheet shows the importance of fawn recruitment and how fast the adult sex ratio can be turned around. Sheets 3 and 4 show the same information with poor fawn recruitment. Adult sex ratios are higher, but never reach more than 1 to 5.

All that this shows is that basically in the real world adult sex ratios are self correcting based on fawn recruitment. Let me know what you think..

Bone Collector,

Does your spreed sheet calculate the fact that adult females are being shot as well as bucks?

No it does not. I was trying to disprove the theory of self correcting sex ratios, so I wanted to leave all females alive to make the ratio as skewed as possible towards females. In the real world where females are being killed by hunters, cars, predators, etc. the ratio will be even tighter than my spreadsheet shows, that is, as long as fawn recruitment is normal. As I stated earlier, buck age structure will be terrible, but adult sex ratios will self correct based on yearly fawn recruitment.

Good work...very interesting data IMO

I noticed that you had each Adult doe produing 1 fawn.
How do or would the ratio number change if each adult doe produced 2 fawns(1male/1female). My reasoning is that I believe that most does produce 2 fawns each year.

Very interesting!

From the little bit of research that I have found on this, mainly does, I didn't find anything really saying that most does produce 2 fawns a year. Don't quote me on that. What I have found is that the older does are more likely to have twins than younger does, but the younger does are more fertile and are more likely to concieve.

Popeye, if you find an article from which you base your info on post a like or something. I wouldl ike to check it out. And don't take this that I am trying to prove you wrong, cause I am not. Just stating that I have only seen what I posted above.

Hey Bowsticker,

No problem. My belief that most does produce two fawns is based purely on my personal observation. I live out here in the boonies and it appears to me that most does have 2 fawns instead of 1. I admit that's not a scientific study nor is it based on an article...wish I had something more concrete to give you but I don't.

Popeye,

I am going to do alitle research and see what I can find on this matter. I would agree that I have seen many does in the last few years w/ more than one fawn. Not sure why, but I am going to try and find out!

Popeye,

I did alittle research and found this.

According to noted deer researcher Harry Jacobson, a primary reason for the whitetails’ success “is its reproductive strategies: The whitetail can breed at an early age, select the best sires in a herd, produce more than one offspring per year, arrange for the young to be born at a favorable time of year, and even alter the sex ratio within the herd to maintain a healthy population.”

So, what you said definatly is correct. I haven't found anything yet on what I said, but im pretty possitive that it is correct as well. Just think if an older doe had twins twice in the same year! I, however, did not know that a doe could alter the sex of the fawn!

You can check more out at Whitetailinstitute.com. Let us know what you find!

Excelent guys! Yes ...popeye and Bowsticker...stays on this and let us know! Very interesting information! Where in Bonecollector? Is he out west on a trip ? Hope he returns soon so he can give us his take! LOL Keep up the good work guys!

Bow Sticker,
This is a great topic. I'll need to check into this more.
I'm definately going to try the Whitetail Institute website but it will probably be this weekend before I have the time.

Natural self-correcting sex ratio....who would have thought that was possible.
Not me.

I guess that the need of maintaining the sex ratio for QDM might be a little overblown.

Where is Bone Collector anyway, I would like to hear his thoughts since he got the ball rolling on this.

Yes, it is very intersting to think that this issue w/ deer managament may be a bit blown out of the water. If does really do change the sex of the fawn depending on what the herd needs! I believe Bonecollector is in the Midwest doing a bit of hunting.

I just got back from hunting Mule Deer and Elk in Colorado. I was fortunate enough to get a 6 x 6 elk that I will post a photo of later.

I am glad to see that my post has generated some discussion. The article I read that got me thinking about this was from the March 2008 issue of Deer and Deer Hunting magazine and was titled "Too Many Does or Too Many Deer?". The author, James Slinsky, was citing research conducted by C. W. (Bill) Severinghaus in New York's Adirondack region over a 12 year period in the 1950's. His research used the actual reproduction rates in a healthy herd of 0.34 fawns born per doe fawn and 1.71 fawns born per adult doe yearly. Also, in nature fawns are basically born in even numbers of males and females. The numbers used in this study actually show 109 males were born for every 100 females. So basically the only time antlered buck to adult doe ratios can be greater than about 1 to 3 is when reproduction falls below 1 fawn per adult doe. The research I have done to this point shows that with poor fawn recruitment (which generally results from an unhealthy herd that is out of balance with the land) and excessive buck harvest it is possible to skew sex ratios for a period of time. However, it seems that eventually nature will self correct the issue.

Popeye, your observation of 2 fawns per doe is pretty close to the 1.71 fawns per adult doe used in the study. I ran the spreadsheet with these numbers and it really didn't change the ratios much at all.

As far as does having the ability to change or alter the sex of an unborn fawn, that is something I have never heard before. I have heard of does aborting or having a miscarriage in years where food supply is low or in areas where deer numbers are above the carrying capacity of the land.

This brings me to the point I believe the author was trying to make. Shooting does is important to keep overall deer numbers in balance with the land which is ultimately what the QDM philosophy is all about with the byproduct being bigger, healthier deer covering all age classes which will yield more big, mature bucks. It is much easier to sell the "skewed sex ratio" argument to most hunters than the "too many deer" argument. What hunter wants to hear there are too many deer where he/she is hunting? Have you ever seen too many deer? Me either. However I have witnessed the results of too many deer for the land to support. Take a drive through West Virginia in the summer and notice the browse line through the woods. There is next to nothing from the ground to about 5 or 6 feet high.

As far as this being a management issue that has been blown out of proportion, I think it is more an issue of something being marketed in a more attractive package to achieve the same results. For me, I still strongly support and fully believe in QDM. I think we should shoot at least 1 doe for every buck we shoot. After all, God made it so that they came into the world in equal numbers, shouldn't they leave the world in equal numbers as well??

Bone I just ran across your post. I did exactly what you did after reading this article last spring. I made a worksheet and posted the experience on the Michigan Sportsman's Forum:

Here is the thread:

http://www.michigan-sportsman.com/forum/showthread.php?t=215254

I went quite a bit further and added some other considerations into the model, including button buck mortality and fawn recruitment. I discovered two ways that the ratios can be skewed. One is the case where button bucks are preferentially killed by hunters. This can happen because button bucks are so dumb and clumsy that they are more likely to be shot by hunters that are not careful enough about shot selection on antlerless deer. Nor are they reported at volutary check stations as often. The second way is to have very low fawn recruitment. At greater than 0.7 fawns per doe recruitment, pre-hunt ratios cannot exceed about 3 does : 1 antlered buck, but if the recruitment falls below 0.4, the ratio can start to get skewed (but this is the extreme case with 100% buck mortality and 100% doe survival). Statewide in Michigan, the DNR reports recruitment of 0.75 which would be borderline, except that buck mortality is only about 70% and doe mortality is about 25%, resulting in about a 2:1 prehunt ratio of does to bucks. Most hunters don't believe this because they see a lot more does than bucks. I think the reasons are threefold. First, does are out and about more than buck because they have those pesky offspring to take care of. Second, they travel in groups in the day time so they are easy to spot. Third, bucks are more nocturnal secretive during hunting season and tend to travel alone so are seen less and noticed less even when they are out and about. I find myself responding to hunters who say things like: my ratios are screwed up, I saw 22 "does" yesterday and no bucks (late gun season usually). Well, if they saw 22 antlerless deer, about 6-8 are adult does. Into the season, doe:buck ratios in Michigan are probably about 3 o4 4 to 1 because of the preferential buck kill. That leaves 2 or 3 bucks for that group of 22, and they were probably on their bellies until dark. If they went out during bow season, they would see about 2 adult does per buck, as my log book indicates.

I self-published a pdf article on my findings at this location:

http://www.scentbuster.com/Doe-Buck_Ratio.html

I can be reached at jbrauker@comcast.net if you have any questions.

Jim

Jim,
Awesome post! You really brought up some things that I think some of us hadn't thought much about! We've had a few down months w/ the number of visits and post. Hopefully just due to people hunting and the holidays. Keep up the good work and pass the word around about the site!

Derek

Jim, you are exactly right. I kept running numbers based on low fawn recruitment and found the same thing, at about .4 ratios do become skewed based on very high buck mortality and low/no doe mortality. However, in the real world this is highly unlikely as you mentioned with your info relating to the Michigan DNR. Also, even if ratios can become, or are skewed, it is amazing how quickly they recover based on elevated fawn recruitment even with high percentages of bucks being killed. The key to it all is fawn recruitment.

Bone Collector wrote:

Jim, you are exactly right. I kept running numbers based on low fawn recruitment and found the same thing, at about .4 ratios do become skewed based on very high buck mortality and low/no doe mortality. However, in the real world this is highly unlikely as you mentioned with your info relating to the Michigan DNR. Also, even if ratios can become, or are skewed, it is amazing how quickly they recover based on elevated fawn recruitment even with high percentages of bucks being killed. The key to it all is fawn recruitment.

If this kind of information becomes widely understood among hunters, it clears the way for what really is important, and that is not the sex ratio, but the ratio of mature bucks to immature bucks. In Michigan 70% of all bucks are killed every year, and 80% of that 70% are 1.5 year olds. It would only take two or three years of reduced harvest of 1.5 year old bucks to dramatically improve our hunting.