WATCH: Improve Your Hunting With Realistic Deer Management Goals
The number of deer inhabiting a property is important, but regardless the population survey technique employed, the findings are, at best, an estimate. Can you reach your goal of producing heavy-racked bucks without knowing precisely how many deer are on your land?
Deer management is a numbers game. Too many deer means a significant amount of pressure will be placed on the habitat. An abundance of male fawns equates to an increase in buck numbers and a higher probability of trophy caliber deer because more bucks will potentially reach the mature age classes when they are capable of developing those larger racks. Too few deer and hunter success plummets.
Statistics are important. Everyone wants to know how well their 401K is performing, a number that is precise, but fluctuates daily. When it comes to managing deer on small properties with a goal to increase the number of bucks reaching maturity, it’s difficult to know exactly how many deer exist, and more importantly how many actually live on the property.
So how can sportsmen manage for quality deer without knowing the number of deer that exist on the property? First of all, a goal should be established. For example, the goal for Ranch DDH is the development of mature bucks that exhibit racks that gross score above the county-wide average.
Not only is this goal realistic, it is achievable. More importantly, however, are the objectives that lead to the goal. One objective might be that mature (41⁄2+-year-old) bucks in the harvest gross score on average 145 inches. Thus, on an annual basis when the harvest data is tabulated, should the average gross score for mature bucks exceed 145, the management practices are effective.
However, if the average gross score is below the benchmark, you might not be employing an effective strategy. Should no mature bucks be harvested, you can assume that few exist and a reduction in the buck harvest is required.
The point is, harvest data is actually more applicable than population data. In other words, if antler size and body weight of deer per age class continues to increase on an annual basis, how many deer exist is actually irrelevant but obviously nice to have.
The impact deer have on native vegetation is also important because it represents both nutrition and cover, and it’s important to be familiar with those plants preferred most by deer. For example, whenever I visit a new ranch I inventory the vegetation, listing the species observed in a table based on their preference level. By doing so, I can determine the quality of the vegetative community based on the number of the top 10 species preferred by deer. I also conduct a bite stem count on those highly preferred plants.
Results are based on the number of bites by deer observed on the vegetation analyzed. This information allows me to numerically and visually measure the impact deer have on the plant community. For example, 10 to 30 bites per analysis of 100 stems on a highly preferred plant is normal, but 60+ bites would be quite high, and an indication of an excessive deer population.
The consumption of non-preferred plants such as cedar also tell a story. Since deer rarely consume cedar, bites by deer on this species indicates both an abundance of deer, and that preferred plants are extremely limited. The point is that awareness of the impact deer have on preferred vegetation encourages managers to adjust the harvest in order to assuage the acute demand deer place on the environment. Should minimal use of the vegetation by deer be determined, a reduction in harvest might be in order.
Although it is not imperative to know the exact number of deer on a property, there are some easily obtained population parameters that are extremely helpful for managing a deer herd. These include sex ratio, age class structure of bucks and fawn survival. These statistics can be obtained by incidental sightings, or what I refer to as windshield biology. Basically, sportsmen take time to record all deer sightings throughout the fall and winter period. Data collected includes doe, buck and fawn numbers, which yield extremely accurate measurements of both the adult sex ratio and fawn survival.
Observers can also record the age of bucks observed. By doing so, they can determine the age class structure for the male segment. To a manager interested in producing older, larger-racked bucks, it’s important to know what percent of the deer herd is made up of mature bucks. And based on my experience, a minimum of 45 percent of the bucks observed should be in the mature age class before exceptional antler quality can be expected.
What is important to understand about surveying deer populations is that like aging deer based on tooth wear, the techniques employed are not always accurate. For example, there was a time back in the 1970s when I believed we could see 100 percent of the deer on a South Texas ranch whenever we utilized a helicopter. And although I now know that this is not the case, I still employ the technique because of its collateral benefits.
And even though 50 percent of the deer could go unobserved while conducting an aerial survey, it remains the most rapid method of gathering an abundance of data in the low-lying brush environment characteristic of South Texas. But like any tool employed, whether it’s a spotlight or a helicopter, the experience of the individual conducting the survey makes a difference.
Timing of a survey is also critical. In South Texas, aerial surveys are sometimes conducted as early as August, but results are less accept- able because of the excessive temperatures at this time of the year that restrict deer movement and reduce deer observations. The dense understory is also a concern because it provides additional opportunities for deer, particularly those older, reclusive bucks, to avoid being observed. The most productive data gathering time period is during the post hunting season, or late January through February, when temperatures are more conducive to escalated deer movements and leaves have desiccated, increasing visibility.
Whenever I conduct an aerial deer survey, I don’t just record buck, doe and fawn numbers. I segregate buck observations into five distinct categories. No. 1 includes all yearling spikes; No. 2 contains all yearlings and 2-year-old deer with branched antlers; No. 3 includes all middle-age bucks (3 to 4 years of age); No. 4 includes all mature bucks (5+ years old); and No. 5 includes all bucks exhibiting above average sized racks exhibiting a benchmark antler size designated by region.
For example, in South Texas, a free-ranging buck that gross scores 160 inches is considered exceptional, while in the Hill Country it might be in the 140-inch range. An increase or decrease in trophy caliber bucks can be considered as a measurement of management. But by collecting this data, you can break down the deer herd into age classes. Simply put, if we don’t know the age class structure of the males, a mature buck harvest is difficult to recommend with confidence. More importantly, if few mature bucks are observed, it means that too many bucks are being harvested, and a reduction in the male harvest should be considered.
A helicopter is also an ideal tool to obtain collateral species information. This includes quail, turkeys, hogs, coyotes, hawks, exotic hoof stock and at times domestic stock. All of this information affords the manager a means of diagnosing potential problems. For example, if a high density of coyotes is observed and a low fawn survival is experienced, predator control might be warranted.
The deer survey is simply that — a survey, not a census, where every animal is accounted for. But it does provide a substantial amount of data that can be employed to enhance the quality of life for all species occupy- ing the area.
COST EFFECTIVE CAMERAS
One of the most effective methods of gathering population data is the use of motion detection cameras.
By positioning cameras over bait on a densely wooded 10,000-acre in southern Mississippi, Dr. Harry Jacobson and his colleagues from Mississippi State University found that during a period as short as 10 days, 97 percent of the bucks and 72 percent of the does they had marked were caught on film, making cameras an efficient tool for surveying deer populations. This technology represents one of the most efficient and cost effective methods of obtaining deer population data.
Knowing exactly how many deer inhabit your property is virtually impossible, but habitat and herd condition can be measured, which is vital to making management decisions. After all, if the average antler dimensions of mature bucks in the harvest meet your expectations, it is reasonable to assume that deer are in good shape.
The collection of population and morphological data consolidated and compared annually represents a road map when it comes to achieving management goals. Thus, the more information collected, the closer you come to actually knowing how many deer exist on a property, and more importantly how many can be harvested without disturbing the overall quality of the herd.
— Bob Zaiglin is a certified wildlife biologist from South Texas. He has been a D&DH contributor for more than 20 years. He is the CWB Coordinator of Wildlife Management, Southwest Texas Junior College.