The
Biology Behind QDM
Ted Wawrzyniak BS, RRT
Wildlife Biologist, MN QDM Inc.
By now, you have heard about the biological merits of QDM. You have
heard about how QDM creates a biologically sound and balanced herd.
So what exactly does that mean? It is important that you know the
answer to this question so you can help to spread the word about QDM.
To answer this question, let’s look at the two harvest strategies
involved in QDM. That is adequate doe harvest and restriction of the
harvest of young bucks.
Most importantly, QDM encourages adequate adult doe harvest. Adult
doe harvest accomplishes two things. It is by far the most effective
method of holding deer populations to a sustainable level and it balances
the buck to doe ratio to a more natural level. Adult does are the
most productive segment of the deer herd. They are the most likely
to successfully raise one, two, and even three young the next year.
So by taking an adult doe, you take out 2-4 deer from next year’s
deer population. The harvest of a buck or a fawn only eliminates one
deer. On the surface, this may alarm some people. You may anticipate
a large decline in the population. Some have asked, “What happens
if we have a bad winter?” This is exactly why we need to decrease
the deer population. Before I explain what I mean, let me give you
a couple definitions. The carrying capacity is the maximum level that
a particular habitat can maintain. This capacity goes up and down
with certain conditions. With recent mild winters, this capacity has
increased steadily. In some of the more agricultural regions, this
capacity has increased even more than other areas. I doubt that we
are at that level because we would have to have virtually no hunting
season to maintain this, however, we are likely very near that level.
This is why you see the liberal doe harvest limits. Another level
which is extremely important is the sustained yield. This is a level
in which the maximum number of fawns are born and survive. This is
a level in which deer are in the best condition, in which they have
plenty of food, cover, and water. Their weights going into winter
are the highest and they show an increased resistance to stresses.
Now, I can go back to why we need to lower our deer population. Currently,
with the state of the deer herd, a severe stress such as disease or
a bad winter could decimate the population. With the population at
this lower sustained yield, the deer will likely be more than adequately
prepared to deal with any stress that it could face. Deer populations
will remain much more stable and predictable. This makes deer populations
much easier to manage. When populations are near carrying capacity
stresses such as bad winters can bring the population to well below
sustained yield levels, possibly requiring the DNR to severely restrict
harvest or even cancel the hunting season all together for a year
or more. The DNR tries to manage deer numbers closer to the levels
of this sustained yield. I have not been able to have a discussion
with a DNR Biologist regarding what level they try to maintain, but
it is generally 50-60 percent of the carrying capacity. The DNR regularly
evaluates what levels they would like to maintain in each area of
the state based on a particular sustained yield and sets harvest regulations
based on that level. There is much more population dynamics that go
into population levels being held near carrying capacity, but that
goes beyond the scope of what I want to accomplish with this article.
You can increase the sustained yield level in your area by planting
food plots and managing your habitat to provide food and cover. These
areas are covered in other parts of this and other newsletters.
A natural buck to doe ratio is about one buck for every doe (1:2).
It was proposed by Guynn (1991) that deer herds should be managed
so that the natural structure of populations is maintained. This goal
ensures that the behavioral and biological mechanisms that shape deer
populations are allowed to function. The density, sex ratio, and age
structure should mimic a population regulated by natural predators
and hunting by the Native Americans. Elder (1965) reported age composition
of prehistoric Native American deer harvest based on mandibles from
three sites in Missouri. Age compositions from the sites are remarkably
similar and suggest that the Native Americans killed few fawns (8
percent or less), many deer survived to older ages (20 to 26 percent
was 6 ½ years or older), and longevity of deer was great (some
deer were 10 ½ years or older). Obviously, we are currently
nowhere near this level with our harvest.
The other harvest management strategy that QDM promotes is a restriction
in the harvest of young bucks (all of the yearlings and most or all
of the 2 ½ year olds). This will create a buck age structure
that consists of many more mature bucks in the population. This improved
age structure, along with a balanced buck to doe ratio, is what we
are talking about when you hear about a “natural or balanced”
herd or population. It is what QDM advocates consider a “biologically
sound” herd.
So what does this all lead to? What does this create other than simply
“larger racks”? Of course, you see bigger and healthier
deer all around (including does) that are able to maintain a steady
population level through all the stresses that they may encounter
(winter, drought, disease, etc.). What you don’t see is that
only the older, most dominant and genetically superior (and healthiest)
bucks are doing the breeding. This allows for natural selection to
run its course. You not only have genetically superior bucks, but
you have genetically superior does as well. In the presence of mature
bucks, the testosterone levels of yearling bucks is suppressed, resulting
in only the superior, mature bucks that win the right to breed to
do the breeding. Does are generally bred over the span of 30 days
rather than 90. Now you want to talk about a quality hunt. The sight
of a mature buck charging to your grunt call, doe scents, and rattling
antlers is just about the most rewarding experience anyone can achieve
(even if you don’t shoot anything). Very few hunters in Minnesota
even know what this feeling feels like, but when they do, they will
never want to go back. These 30 days will be the most intense period
of time you could imagine. This is in my opinion, a hunt of greater
quality than anything that is possible right now. And I’m not
even talking about shooting anything yet! At this point, it really
doesn’t matter. Remember, the sport is called hunting and not
shooting. I have had years where I did not shoot a deer and still
had a great time while I was “hunting”. Yes, it would
be nice to have a nice buck on my wall, but the experience is what
most QDM advocates are after. In fact, I would have even a greater
experience shooting does if I know that I may get to see a buck every
time I go out and blow on my grunt call. Maybe my wife would even
quit yelling at me every time I came home smelling like doe pee, knowing
that I actually have a chance of that stuff working.
The biggest complaint you hear from some people is that QDM is all
about “large racks”. This is a statement made only by
the uneducated, because as you can see, QDM is a package deal. No,
there really is no detrimental effect of having a buck to doe ratio
of 1:7 (as an example). You can’t give a simple explanation
of why it is wrong to have a messed up buck age structure in which
90 percent of all bucks are yearlings or less. It is all tied in to
a larger picture of which doe harvest is the cornerstone. If you don’t
believe that, than QDM is not for you. If all you are trying to get
out of QDM is “larger racks”, please move to Texas and
practice what you truly mean to practice – trophy management.
QDM in Minnesota is going to be what it truly was meant to be. That
is something that focuses on the big picture. Looking at the population
as a whole and using sound biological principles to attain a hunting
experience that is of the highest quality possible. Yes, larger racks
are a product of a more natural population. That is what gets all
the attention because they are promoted on TV shows, magazines, and
in hunting clubs. Unfortunately, you don’t see too many pictures
in magazines of the mature doe that someone shot during muzzleloader
season. It is human nature to want to get something that is bigger
than everyone else’s. I will admit that I dream of shooting
“The Big One”. But how can you not get excited about that.
We as deer hunters do not have to make any excuses about our passion
for deer hunting and the quest for a trophy. But anyone practicing
QDM knows the importance of doe harvest and how it all ties into the
big picture. In addition to that, I haven’t even mentioned that
QDM advocates often use does to fill their freezers with delicious
meat.
Make sure you make plenty of copies of this article, because next
time you get a question like: “What is a balanced herd structure?”
or “Why do you want a balanced buck to doe ratio?” or
“Isn’t QDM only about bigger racks?”, simply tell
them that QDM is a package deal. It can’t really be explained
in one part. Give them this article. I think it will help them to
get a feeling of why we practice QDM in Minnesota. They can email
me at tedw@mnsportsmen.com if they have any more questions. From time to time, I
may adjust or add to this article, so please check our website (www.mnqdm.com)
for the latest version. I hope this article will influence they way
you approach your hunting season this year. If it does, please email
me with how it changed your experience. I always enjoy hearing about
those sort of things.
Literature cited: Miller and Marchinton. Quality Whitetails (1995)
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Webmaster's Note: MBI has not yet taken a formal
position relative to QDM. This article is presented in the interest
of providing Minnesota bowhunters with information from a variety
of sources.