Well, I think it is about time to pull another post up from the SE Deer Study Group that I attended at the first part of last week in Tunica, Mississippi. I will write about a commonly used trail camera survey used by wildlife professionals, land managers, and even dedicated sportsmen to estimate the population of white-tailed deer on a property and get an idea of sex ratio. It was developed by Dr. Jacobson at Mississippi State University.

Nice 3 1/2 yr. old shooter buck from one of my NC properties

For those of you not familiar with the technique, here is a step-by-step guide to using the technique on your property this coming fall. Surveys are most useful if conducted immediately after deer season has ended or in September before deer season starts in the fall. Using a camera density of approximately 1 per 100-150 acres provides sufficient reliability for your estimates. In fact, Dr. Jacobson and his research team found that in a 10 day study, their cameras at the prescribed density took pictures of over 90% of the marked animals in their population.

Once you have your camera locations picked out, pre-bait your survey sites with 10-15 pounds of corn - make sure your local laws allow for baiting!!! Once your bait sites are being hit by deer, engage your cameras to take a picture on a 10 minute time delay. Keep a close eye on your bait sites and replenish as necessary. Also, be sure to always have functioning cameras in the field. A broken camera or filled memory card can have a nasty impact on your census estimates. Keep your bait sites active and cameras taking pictures for 10-14 days. Research has shown that 10 days captures approximately 90% of what you would have captured in a 14 day census, so you can make your own decision concerning that…each day = more $$$.

Now, you have all your pictures either developed or pulled up on your PC. Now you can start working with the #’s.

Count each doe, fawn, and buck in all photographs (early September is good because fawns are more easily distinguished). Count repeat individuals every time they occur in photographs, even if you suspect they are the same deer over and over again…the statistics take this into account. You now have a # of does, fawns, and bucks captured in your pictures.

Wide 7 pt. I photographed in Maryland, 2006.

For the bucks, you need a total number of bucks (including repeat visitors, i.e. if that BIG 8 showed up 7 times over the 10 days, count him 7 times) and a number of individual bucks. As long as the number of photographs of unidentifiable bucks is not a lot, throw these out of the census completely. You now have all the numbers you need. Time to crunch them.

Pull out a calculator and do the following calculations…

To acquire your population factor, Divide the number of unique bucks by the total number of buck photographs (including repeats). Then multiply the resulting # by the number of does and fawns in your pictures. The population factor accounts for repeat visitors. One caution: it assumes bucks and does visit corn piles at the same rate.

Once you have your buck, doe, and fawn #’s, you can compute a buck:doe, doe:fawn ratio, and even break down your bucks by age structure.

All of the above is old news. But there were a couple of precautions presented at the meeting concerning the camera census technique coming from a study of closed deer populations in Texas with a known number of individuals. In the Texas study, the researchers found that the camera census underestimated populations by 25-35%. Also, although a previous study showed that does were equally visible as bucks at bait piles, this study showed that bucks were 1.5-2 times more likely to be captured at bait site cameras. If this was true in your camera census, this would skew your sex ratio.

So, if your overall population is a lot lower than you were expecting, you might consider the potential underestimation using the technique and you might consider that your sex ratio might be tilted a little too much towards the bucks.

Well, I hope you enjoyed the post. I think taking a camera census of a property is most useful is you own large acreage (> 1 square mile, 640 acres), but anyone can do it. Most of all, have fun. Kids love looking through pictures! If anything wasn’t clear, please leave me a comment and I’ll try to clarify. Thanks.