Understanding the Buck to Doe Ratio
May 23, 2012
"The buck-to-doe ratio is all messed up." If I had a dollar for every time I've heard that complaint from an irate deer hunter, I could probably a new bow. Admit it, most of us are looking for a buck, and when we don't see what we want, we have to blame something. We see plenty of does, so that must be the problem -- too many does. There's a lot of faulty logic behind that assumption.
First of all, to avoid confusion, we'll use the term "sex ratio." I've often wondered why it's referred to as the buck-to-doe ratio when does are listed first in the formula. A 4:1 ratio means four does for every buck.
Hunters hear about ratios of 2:1 or even 1:1 as being ideal, but seldom observe anything close to that. We see lots of does and a few bucks and quickly, erroneously proclaim highly skewed ratios of 10:1 or even 15:1.
Mathematically, you can't get much more than 5:1, in the absence of extremely intensive management inside an enclosure -- and who would want to do that?
To illustrate, I'll use an abbreviated version of the example provided in the Quality Deer Management Association's 2012 Whitetail Report. We'll start with a hypothetical population of 120 adult deer, unnaturally skewed toward does with a 5:1 sex ratio -- 100 does and 20 bucks. Hunters kill 90 percent (18) of the bucks and none of the does, resulting in a post-hunt population of 100 does and two bucks -- 50:1.
Next, we'll factor in a natural mortality (old age, vehicle collisions, disease, predation, etc.) rate of 50 percent for bucks and 10 percent for does, though it would likely be more balanced between the sexes. That leaves us with a 90:1 ratio.
Now we'll apply a recruitment rate of 0.66 -- the number of fawns that survive to six months of age. This gives us 60 fawns. Approximately 50 percent of fawns born each year are bucks. The population now has 120 does and 31 bucks -- a 4:1 ratio. Biologically, that's still a rather skewed ratio, but it illustrates how quickly things balance out. Add even a limited doe harvest and things become even more favorable for bucks.
It's also important to note that when biologists refer to sex ratio, they are considering the pre-hunt population. Most hunting pressure is directed toward bucks, so the ratio of post-hunt populations will indeed be skewed toward does.
PERCEPTION VS. REALITY
There's also a perception issue. Antlerless deer tend to be more viewable than antlered bucks during the hunting season. Additionally, most hunters consider all antlerless deer to be does, when in fact, roughly 50 percent of fawns are bucks. And as the authors of the Whitetail Report point out, a 4:1 sex ratio could easily lead to hunters observing 10 or more antlerless (does and fawns) deer for every antlered buck during the hunting season.
If you still think the population you hunt has a skewed sex ratio, maybe you should view it not as a problem, but an opportunity. For starters, there's nothing wrong with shooting a doe or two -- or even three. When I'm strictly buck hunting, I find doe sightings rewarding. But once I make the decision to take any deer, I get just as amped up when a big doe comes on scene as I do over a buck.
An old, long-nosed, mature doe is every bit as challenging to kill as a mature buck, maybe even more so. All a buck has to worry about is itself. An adult doe that has experienced several hunting seasons and numerous negative encounters with two- and four-legged predators is looking out for itself and its offspring. One of my best trophies is a 9â€‰1/2-year-old doe I arrowed late one season.
If nothing else, hunting does is a good warm-up -- a way to test your bowhunting skills with less pressure and less at stake. A missed doe doesn't carry the sting of missing a trophy buck. Putting a doe on the ground, and in the freezer, takes a lot of the pressure off future hunts. And if you're concerned about sex ratio, it's a step in the right direction.
Removing does is actually an important part of proper herd management. Some states, such as New Jersey, have earn-a-buck programs that require hunters to take a doe before they can receive a buck tag. Many outfitters not only allow but encourage hunters to take a doe, and some even give away a hunt the following year to the person who kills the largest doe.
Modern hunters are increasingly, voluntarily, taking on more responsibility as deer managers. It behooves us to have a better understanding of the resource. That means learning about things such as sex and age ratios (the latter of which we'll cover in a future column) and contributing to better herd management in whatever way we can. I for one am happy to oblige by taking out a few does wherever and whenever the opportunity presents itself.