Helicopter Deer Surveys | Population Management is a Numbers Game
By: Justin Bryan and Bob Zaiglin
I have to admit there are few things in life I like more than being in a helicopter, on a well-managed ranch, flying deer surveys in the late summer of each year. I wouldn’t consider myself a “deer freak” but I do enjoy the opportunity to partake in activities that encompass a quality deer population. That’s normal, right? If it is said, that one is the average of his five closest friends I choose to surround myself with hunting enthusiasts.
For those of us that live in country that is agreeable to surveying deer from the air, it is a blessing as this technique, although not perfect, currently provides the best method for evaluating a whitetail population. The other options available include a spotlight deer survey and/or trail camera deer surveys and to say that they are laborious and time-consuming techniques is an understatement, especially on properties that are greater than a couple of thousand acres in size. In addition, the data acquired tends to be of less quality than a helicopter deer survey, although I must admit a helicopter survey is by no means perfect. But the latter two are at times, especially on small properties, the best and most appropriate techniques to use and we as managers understand that.
As wildlife biologists, surveys provide us with an annual review of sorts regarding our prior implemented land management activities and how wildlife have reacted, positively or negatively, to them through the year(s). Being in the air simply provides that 10,000-foot view; the best opportunity to assess a large “sample” of a given deer population. In addition to gathering demographic data, we also have the chance to quickly evaluate current body condition of those deer, native vegetative health, density, spatial arrangement of the habitat, and to take notes regarding other species that are viewed during the deer surveys such as quail, hogs, turkey, coyotes, mountain lions, and exotics such as axis deer, blackbuck, etc. Collecting this data annually, and thus accumulating long-term information, allows us to begin to understand how the world the deer lives in is evolving due to natural events and/or man implemented techniques and how we can best work with that world to meet or exceed our management goals year-in, year-out
August, September, and October are when most surveys for white-tailed deer are flown in Texas. Following a predetermined flight transect; bucks, does, and fawns are counted and additional descriptive characteristics for bucks, such as age categories and antler characteristics are documented as the survey is flown. An example of data that is generated includes the ratio of fawns to does which allows us to estimate the recruitment of fawns into that population for that given year. While the ratio of does to bucks give us an idea of the balance or lack thereof between the numbers of males and females in that population. In addition, we can gain an idea of the current buck age structure (young, middle, mature) for a particular property and finally we can calculate an estimate of the deer density (deer per acre). Thus a picture of a particular population begins to develop.
The number of does, fawns, and bucks a given population consists of prior to the hunting season is important to know if we are to actively manage a given population to some extent via harvest. With this data, harvest recommendations are prescribed that are designed to continue to move this population toward the predetermined goals established by the landowner and the biologist.
Now knowing that helicopter survey data is not perfect, it is not uncommon to fly a second survey in late winter such as January and February to compare with the fall data. Unfortunately, when flying surveys in the early fall months we generally still have quite a bit of leaves on trees and brush, which means some deer will likely be obscured from our view due to the dense canopy cover. In addition, there can be quite a few fawns that are small and thus tougher to detect. All of which we know impacts the quality of our data. Late winter surveys, deep into many freeze events, solves the problem with leaves and obstructive canopy cover and in addition provides a couple of more months of growth for fawns which should make them easier to see. Theoretically, a late winter helicopter deer survey will create the opportunity for better data but only by comparing the fall and late winter data will we fully understand the quality of data we are gathering.
Remember, “If you can’t measure it, you can’t manage it.” If we are to actively manage a population we have to know where we are currently at, where we are going, how we are going to get there and then get busy doing the right things but being flexible enough to make adjustments as needed along the way. If we are not collecting data and evaluating it then we don’t know where we are at nor where we are going. Successful management means being dedicated to doing it right, hire the right people to develop and implement the plan and stay the course.