How to Manage Whitetails on Private Lands: Part 4

Sound management decisions are based on accurate data from the deer you harvest each year, and that is what this installment is all about!

A good friend and colleague once said, “Many a beautiful theory has been murdered by a ruthless gang of facts! Without good data, everyone’s opinion is as good as another!” Each deer you harvest from your land has a huge story to tell you, if only you ask the right questions and collect the most important information.

The average deer hunter kills a buck or doe, tags the carcass, field dresses the animal, throws the carcass into his vehicle and heads home. If the buck is big enough, the hunter probably takes a photograph to post on social media or show to his hunting buddies. That is sum total of data collected from each deer taken either from public or private property!

A Check Station?

Most of you probably are familiar with the check stations operated by state agencies used to collect information about that season’s deer harvest. Data collected usually are pretty rudimentary,
most commonly sex, relative age and sometimes dressed weight.

Some states use “Telecheck” through which you record your harvest, but whether at a check station or online, it is my opinion valuable data are lost that could significantly improve deer management. Just because you are managing deer on private land does not mean you cannot establish your own Check Station, where every deer harvested provides valuable data to your management program.

A check station does not have to be elaborate, just a simple place where you can take your deer before leaving for home. You should have a rule that no deer leaves the property without having the necessary data recorded from it. It is a good idea to have a place where you can get out of the weather, since many deer leave the property after dark in the rain or snow, without having critical data recorded!

The hunter tells himself he will collect it later or get the information from his taxidermist, and that never happens.

So, let’s go over what data are needed. Data should be recorded on a form in a weather-resistant binder (see photograph), and always in pencil! Pencil lead does not run when wet and you can erase an entry if you make a mistake.

Obviously, the first data would be the sex of the deer. Then you should weigh your deer as “field-dressed” weight, meaning with the internal organs removed, and nothing else removed (such as legs). In most cases, field-dressed weight is about 70 to 80 percent of live weight, but it can vary greatly depending on whether the deer has just fed or drank.

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So, field dressed weight is the standard used in deer management. You should have a reliable scale from which to hang your deer, and it should be checked regularly for accuracy. I once got a call from one of our technicians, all excited about an almost 10-pound weight gain by the bucks at the property!

Fortunately, I carry a standard 10-pound weight with me for checking scales, and I checked it on arrival. It turned out the technician would hook the scale to the leg of the deer, then crank it up off the ground to get the weight. The act of doing that over and over had stretched the spring in the scale, and the 10-pound weight quickly revealed the problem. Needless to say, the deer had not gained 10 pounds that year, as much as I would have liked to see that.

Next, you should field age your deer, by examining the teeth. To do so, you may have to cut the jaw, something you don’t want to do for a buck you plan to mount. To eliminate the need to do so, we keep a commercially available jaw spreader (available from online sources) to avoid having to do this. We keep it conveniently hanging near the scale.

A good flashlight also should be available for seeing into the mouth of the deer. Now, I know what you are saying to yourself: “I hear that aging deer by their teeth is not very accurate, and besides, I don’t know how to do it!” First of all, there is variation in anything you measure on animals, and tooth wear is certainly one of them.

We have been working with hundreds of landowners over the last 50 years, and we have developed a workable system for getting a reasonably accurate age. We train each hunter how to remove the lower jaw on one side, using the jaw spreader and a pair of pruning loppers. He then fills out and attaches a tag (provided) to the jaw and drops it into a wire fish basket hanging out of the weather at the check station.

The hunter can record what he thinks the age is, comparing the jaw against a laminated chart or set of jawbones kept at the check station. Later, the biologist or manager can go through the jawbones, check the age, and correct what has been recorded.

We schedule “aging bees” with our hunters and go over the jaw from his deer. Believe it or not, by using this method, we can quickly train every hunter how to accurately assign age to his deer! We now have cooperators who can age a deer as well or better than many professionals!

For those of you who still want more accuracy in aging, there is always the cementum annuli method, which will require you to remove an incisor and ship it off to one of the laboratories offering this service. There a technician will decalcify the tooth, imbed it in a medium, and section it using a microtome slicer. The sections are stained and the deer is aged using the number of growth rings in the tooth. Cost varies but generally runs about $25 per tooth.

There still is disagreement, however, about the accuracy of this method, especially in older deer. Then again, nothing is ever 100 percent correct. Most managers agree that, with training, the tooth wear and replacement method is adequate for most management decisions.

As with aging live deer, we learned that you really do not have to age a deer to a specific year, rather to one of the following age categories: fawn, yearling, immature (2 1/2 to 3 1/2 years), mature (4 1/2 to 5 1/2 years) and over-mature (6 1/2-plus years).

The value of keeping data on ages of bucks harvested from your property over time, is that you can easily assess the effectiveness of your management program. I worked to improve the distribution of bucks harvested at the Turtle Lake Club (Hillman, Michigan) from 2005 vs. 10 years later (2015). We saw clear progress toward their stated goal of producing older bucks.

Manager Wayne Sitton jealously guarded the keeping of harvest records from EVERY buck taken over those years, and he continues to do so even today. That is just one metric for deer management. I will provide additional examples later in this series.

It is important you obtain the proper measurements also for the antlers of each deer. There are two ways to go about this. First, you can measure each antler using a Boone & Crockett or Pope & Young measurement form for each buck. This will provide you with all the detail you will need in later analyses.

Some managers just record the numbers of typical and non-typical points for each side and collect the measurements for what I call the “Frame Score.” It effectively measures the “size of the box” it would take to contain the antlers; in other words, a “beauty” index. The frame score is calculated by recording the average length of the tines, the average main beam length and the inside spread.

An impressive buck would have the following measurements: average tines (9 inches), average beam length (24 inches), and inside spread (19 inches) — 52 inches total. We require our cooperators to collect all Boone & Crockett measurements, but still calculate the frame score from the form.

There is still more to record about the deer. If it is a doe, we examine the utter to see if it still has milk in it; something you can do when you field dress it. A doe can wean her fawn(s) and still have a small amount of milk in her utter for weeks. Sometimes it may be brownish in appearance. If there is milk of any type present, there is a place on the record form to record “In Milk.”

This is important in obtaining a comparison against your visual sightings and trail camera data. If a doe was in milk at time of fall harvest, that means she nursed at least one fawn that summer, which is a conservative indicator of fawning success. This is expressed as “percent lactation,” in later analyses, or the number of does in 100 that had nursed at least one fawn. That is where the term, lactation rate, originated.

That is all the physical data you will need to govern decisions about your deer herd. Yet, there is more you can look for, although not necessary for the average property. You can also examine the deer for external parasites such as ticks and keds (flightless flies), and record a general classification of abundance: absent, low, moderate and heavy.

We also examine the carcass for injuries or signs of infections, and record any found as a description of the appearance. We also examine the hooves of each deer, looking for signs of Epizootic Hemorrhagic Disease (EHD), which is manifested as an obvious line across the hoof where growth was interrupted while the deer was suffering from the disease and not eating.

Finally, if your land is in a state with a late doe (antlerless) season, you may be able to determine when your deer are breeding, as well as, what the coming year’s birth rate will be. There are several states that offer a late antlerless season of one type or another that will allow you to identify fetuses in the doe you harvest. There is a fetal scale on the market that we trust and use regularly to measure fetuses that will give you a statistically accurate age of the fetus.

About the Author

Dr. Kroll is founder and director of the Institute for White-tailed Deer Management & Research in Nacogdoches, Texas.