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A View From Afar
by Dr. Mickey Hellickson
 Though my education in deer management and my career path have taken me to Texas, I always dreamed of applying what I learned in my home state of Iowa. In the agricultural Midwest, the potential for QDM is likely higher than it is anywhere else on earth. Long-time readers of Quality Whitetails know that my dream became a reality in 1996, when a partner and I leased the hunting rights to a 1,480-acre tract in south-central Iowa. Implementing QDM techniques in Iowa has been a learning experience, one that I have shared in previous articles, and looking back over the evolution of our efforts, it is clear that much of our success has been made possible by our deer surveys using infrared-triggered trail cameras. The adjustments we have made to our survey methods over the last 10 years, and the ways in which our data has documented and even enhanced our success, may help other deer managers hoping to start their own camera survey.
How Many Deer Are There?
When we acquired our Iowa lease, our first order of business was to survey the deer population to determine adult sex ratios, fawn recruitment, buck age structure, and how many deer were present on the property, all of which are prerequisites for establishing accurate harvest quotas. The first two years we employed the survey techniques that the Iowa DNR was using to survey the state’s deer herd.
During winter 1996 we hired a pilot and flew a plane over the property to survey the deer herd. Unfortunately, the speed and altitude required to keep the plane in the air meant that many deer were neither seen nor counted. In addition, because of the speed and altitude, it was not possible to accurately separate the deer that were sighted into sex and age groups. In the end, the plane survey only provided a gross underestimate of the total number of deer present and little else.
As a result, the next fall we initiated a series of spotlight surveys on the property. Unfortunately, this technique proved less than ideal as well, mostly because deer were not sighted as they occurred in the population. Bucks, especially older-aged bucks, were more likely than does to flee from the approaching vehicle before being counted. And fawns were undercounted due to their shorter stature and the decreased likelihood of seeing their eyes shine in the spotlight. We counted an average of 16 does, six fawns and only two young bucks during the surveys. This resulted in an undercount of the population, as well as a very biased estimate of the adult sex ratio (an unrealistic 8 does per buck), fawn recruitment (only 38 percent), and buck age structure (0 percent mature).
Iowa’s First Trail Camera Survey?
Finally, after these two survey techniques failed miserably, we made the decision to invest in infrared-triggered trail cameras. During fall 1997, we purchased two CamTrakker units and initiated what may have been the first-ever trail camera survey of an Iowa deer herd!
That first trail-camera survey more than 10 years ago taught us volumes about our deer herd. We rotated those two cameras across six different sites, taking more than 700 photos of our deer herd over the course of two months. We were able to identify 32 different bucks (versus only two different bucks sighted during the earlier spotlight survey). It is likely however, that this first estimate of the buck population was still conservative, because only six camera sites were used resulting in a relatively low camera density of one per 250 acres (one camera per 100 to 160 acres is recommended; see the do-it-yourself guide on page 65 for more details about conducting a camera survey).
Within the 700 photos we counted 187 buck occurrences, 381 doe occurrences, and 359 fawn occurrences. The resulting adult sex ratio was 2.04 does per buck (versus the 8.0 does per buck from the spotlight survey), while fawn recruitment was 94 percent (359 divided by 381; versus only 38 percent from the spotlight survey). Of the 32 different bucks identified, we estimated that 17 were yearlings, eight were 21/2 years old, six were 31/2 years old, and one was mature (51/2+ years old). By comparison, no bucks older than 11/2 years old were sighted during the spotlight survey.
The above ratios resulted in a population estimate of 158 deer (32 bucks, 65 does [32 x 2.04], and 61 fawns [65 x 0.94]). This population estimate translates to one deer per 9.4 acres or 68 deer per square mile. Again, this was likely still a conservative estimate because our buck population estimate was conservative due to the low number of camera sites. By comparison, our spotlight survey on the same property that same fall resulted in a ridiculously low estimate of only 24 deer (one deer per 61.7 acres or 10 deer per square mile), which was more than six times lower than the estimate by trail camera. Our plane survey the previous winter resulted in an estimate of 91 deer (one deer per 16.3 acres or 39 deer per square mile).
What To Do With The Results?
Finally, we felt comfortable enough with our survey technique and the resulting estimates we had of the deer population and the various ratios to implement harvest quotas. We were afraid to implement a doe harvest the first two years of our lease because our plane and spotlight surveys indicated that we had relatively few deer and no older-aged bucks! Now, thanks to the trail cameras, we had a much more accurate "picture" of our deer herd upon which to base our harvest quotas.
As a result of only identifying one buck above 31/2 years old, we established a very conservative buck-harvest quota. Further, because the majority of our lease membership wished to limit the buck harvest to mature bucks only, we implemented very selective buck harvest criteria targeting bucks estimated to be 51/2 years old or older. Now that we knew we had a lot more deer than either the spotlight or plane surveys had indicated, we also intensified our doe harvest. Due to the poor buck age structure and the low number of mature bucks, we instructed all members to try to harvest an adult doe instead of a buck that hunting season. The resulting harvest for the 1998-99 deer season was 10 adult does and one 41/2-year-old, 145-inch, 9-point buck.
The Camera Survey Evolves!
Over the ensuing years we continued the trail-camera survey, using the results to monitor annual trends in the deer population and set harvest quotas. Over time however, our camera survey evolved to the point that we also used the images to develop a "shoot–don’t shoot" list of eligible and ineligible bucks. The images of individual bucks were used to estimate age and antler size to identify bucks that appeared to meet our very strict harvest criteria, as well as middle-aged bucks with great potential that should be protected. Eventually, a "shoot–don’t shoot" guide was printed in color, spiral bound, and provided to each member before the annual December shotgun hunt.
The fact that I had put into print my on-the-hoof age and gross Boone & Crockett (B&C) score estimates of all individually photographed bucks before the hunting season allowed for measuring the accuracy of my estimates. When these same bucks were later harvested, aged by Matson’s Laboratory using the cementum-annuli technique, and measured to determine gross B&C score, we could compare my before-harvest estimates to the actual measurements after harvest. Over the years, our members have harvested 20 bucks for which I had previously estimated ages and scores. My age estimates were accurate for nine of 17 bucks (53 percent), within one year for six bucks (35 percent), and within two years for the remaining two bucks (12 percent). I tended to overage bucks, missing their actual age by an average of 0.5 years. Based on this result, I will be more conservative with my on-the-hoof age estimates in the future.
When I estimate a buck’s gross B&C score on the hoof, I always "frame" the score by guessing a 5-inch range instead of taking the time to try to guess the exact gross score. My score estimates accurately framed the actual score for six of 20 bucks (30 percent), were within 5 inches for nine bucks (45 percent), were within 10 inches for four bucks (20 percent), and missed the mark by more than 10 inches for one buck (5 percent). I tended to overestimate the gross B&C score, missing the actual score by an average of just under 5 inches. In the future, I will also be more conservative with my on-the-hoof antler-score estimates.
Once you have taken the time to estimate the ages of all of the different individual bucks that are photographed, it is a simple matter to also calculate the buck age structure, which is the ratio (or percentage) of bucks within each age class. This buck age structure can then be used to compare to previous years to determine if your harvest restraint of younger-aged bucks has been successful in producing an older buck age structure.
What Else Can You Learn From A Camera Survey?
Obviously, purchasing trail cameras, batteries, film and/or memory cards is expensive, not to mention the labor required to check cameras and re-bait camera sites. Therefore, we have tried to maximize the information gained each year from our camera surveys. In addition to the number of buck, doe, and fawn occurrences; the number of individual bucks identified; and the development of a "shoot–don’t shoot" list, we also maintain the following additional records by camera site:
1. Ratio of buck photos taken during daylight hours. This information is helpful in selecting hunting stand sites. Obviously, stands near camera sites with the highest ratio of daytime buck photos are likely better hunting areas than camera sites where nearly all bucks are photographed at night. Not surprisingly, this ratio varies considerably from one camera site to another based on the amount of nearby security cover and other habitat features. Our best camera sites result in 50 to 60 percent daytime photos, while the worst sites will not have any daytime buck photos. On average, around 25 percent of our buck photos are taken during daylight hours.
2. Number of individual bucks by camera site. Again, this information is obviously helpful in selecting stand sites. At our best camera site, we photograph an average of nearly 20 different bucks each year. Not surprisingly, this camera site is just inside our largest block of timber. We photograph an average of less than three bucks each year at our worst camera site and an average of 8.5 different bucks at all camera sites combined.
3. Number of individual bucks estimated to be mature by camera site. In our case, we do not classify bucks as mature until we judge them to be 51/2 years old or older. Based on this criterion, we keep totals of the number of different mature bucks photographed each year by camera site. At our best camera site, we photograph an average of one mature buck each year. Of the 30 different permanent camera sites that we maintain, we still have yet to photograph our first mature buck at 10 of these sites.
4. Adult sex ratio. Surprisingly, the adult sex ratio can vary widely from one camera site to another. In our case, the average has varied from a low of only 0.5 does per buck to a high over 15 does per buck. The adult sex ratio information is helpful in selecting stand sites as well. If you are targeting does during a particular hunt, or you just want to see a lot of deer, you would obviously want to select a stand site nearest the camera site where the adult sex ratio is most skewed toward does. If, on the other hand, you are targeting bucks, you should hunt where the ratio is most skewed toward bucks to not only increase your odds of seeing a buck, but at the same time decrease the odds of your location being detected by a doe. Other trail-camera studies have determined that the adult sex ratio can vary by season on the same property. Therefore, we make an effort to conduct our annual survey during the same time frame each year.
5. Fawn recruitment rate (ratio of fawns per doe). In addition to the above, we also track the fawn recruitment rate each year by camera site. Our long-term average fawn recruitment rates vary from a low of 0.36 fawns per doe to a high of 1.73 fawns per doe. If one of your harvest goals is to orphan buck fawns by removing their dams (to improve the odds that these fawns will remain on your property), you can select stand sites nearest camera sites where the fawn recruitment rate is highest. If your goal is to harvest "barren" does, you can select stand sites nearest camera sites where fawn recruitment is lowest.
Using Trail Cameras To Identify Important Habitat Features
Once you have acquired several years of survey data from the same camera sites, you can even start to make judgments of your habitat based on the results. In our case we now have six years of survey data from the same 30 permanent camera sites on our core property.
We can identify habitat characteristics that bucks select based on the habitat present at sites where high numbers of bucks are photographed, but absent at sites where few bucks are photographed. We have 10 different camera sites where an average of 10 or more different bucks are photographed each year. Common habitat features shared by these 10 sites include proximity to security cover, type of security cover (either a large block of timber or an area of smaller timber buffered by dense cover such as eastern red cedar), and terrain features that "bottleneck" buck movement (such as a fenceline, a pond, or intersecting "fingers" of timber). Our survey results also allow us to identify habitat features important to does and fawn recruitment by identifying those features that are unique to camera sites where the adult sex ratio is most skewed toward does and where recruitment rates are highest.
Once you learn the habitat features that are important, you can modify your property to increase the number of these features. Most of our habitat improvement projects have been targeted toward adding features important to bucks. During the past several years we have planted tree seedlings in corridors to connect large blocks of timber; we have planted conifers along the outside edge of smaller timber stands; we have modified existing cross-fence by cutting gaps in the fence nearby other terrain features; and we have even constructed several small ponds within timber stands to create bottlenecks for buck movements.
Investing in Camera Surveys
There are many quality cameras on the market these days. Do you homework, ask around, and select a durable, practical camera that takes clear, sharp photos. Purchase as many cameras of the same make and model as your budget allows. In our case, we mistakenly purchased the most economical cameras available each year. We now have eight different camera models and eight different sets of instructions and battery types.
Many deer managers overlook camera surveys because they can’t see beyond the intial cost of the cameras. While it is true this project may sting your wallet, remember that you can use camera rotation to reduce expenses. Also remember that the cameras should be useful for years to come. More importantly, the amount of information you can gather will greatly enhance your QDM efforts and your hunting success. Pool the resources of your hunting club members or Cooperative members if necessary – it’s an investment that will pay off!
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