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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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.