Census Your Deer Herd with Moultrie Cameras

Over decades of trial and error, my team at the Institute for White-tailed Deer Management and Research in Nacogdoches, Texas, has simplified our techniques for using trail cameras to conduct whitetail census work. So, using our methods, you can easily conduct a trail camera herd survey on your property. Here is a step-by-step tutorial on how to do it.

Our research has proven you need a camera density of one to 80-acres, but the cameras must be distributed systematically to account for all your habitats. Now, I know full well that everyone reading this has at least 80-acres, and all land is square, right? Nope. You must adjust the census to fit your property. If you have less than 80 acres, one or two cameras may be all you need to obtain reliable results. Unless your property is high-fenced, you will be sampling 80 acres no matter how small your property. It just includes the neighbors.

First overlay an 80-acre grid over the property (see attached image of 291-acre property). How can you do that? Eighty acres contains some 3,484,800 sq. ft. of land. The square root of this large number is 1,867 ft., which represents the sides of a square with 80 acres inside. Find the scale of your aerial image (easy on Google Earth) and draw a square over any part of your property that has 1,867 ft on each side.

Next create an 80-acre grid that best fits over most of your property. In this case, it takes 5, 80-acre squares. So we are sampling 400 actual acres (including some neighboring property).

Once you have your map grid completed, you can distribute a camera as near to the center of each grid as practical. Obviously, if the center falls in the middle of a pond, you cannot place a camera in that exact location, but you can get as near as possible. In this example, grid square one contains only a small portion of the property on the northern edge, so you would locate the camera station as near to the northern boundary as possible (red star).

It’s important to consider if you’ll be allowed to legally use bait or attractants during your herd survey. Of course, check your state and local wildlife regulations and game laws before doing so.

If you are allowed to bait, I’ll explain the proper setup for your trail camera station. In most cases, the camera should be pointed to the north to avoid solar flare. It should be positioned on a tree or post no more than 30 inches above ground. Corn is the best bait, and it should be distributed on the ground about 15 feet from the camera. You may need to visit the site periodically to replenish corn during the duration of the census.

A confounding factor can be wild hogs in some areas, that quickly discover the baiting site. We discovered that there are other baits that do not attract hogs as well as corn. We have had some luck using cottonseed as our bait; as hogs do not seem to like it.

The ideal duration of the trail camera census study is 10-12 days. I like to use a photo delay setting of 3-5 minutes on baited cameras. It is not a good idea to use video. The number of photographs obtained will be highly variable, depending on the size of your deer population. I usually collect 50-600 photographs per camera station, using a 5 minute delay.

If you are tempted to use one of your feeders, instead of spreading corn, you will bias your study toward bucks. They tend to dominate feeders, and does sometimes shy away from them, which in turn can skew the counts. While feeders are great for attracting deer and preserving corn during hunting season and throughout the year, they’re not ideal specifically for census surveys, I’ve found.

Now to the those of you in the growing number of states where baiting is illegal. When we conduct trail camera surveys in these states, we look for likely locations to incidentally photograph deer as they move about the property. You should look for well-used trails, creek crossings and seasonally, feeding areas. The edges and entrances to food plots or agricultural fields can be productive locations for sampling your deer population. Funneling areas caused by topography, fences and dense vegetation such as young forest plantations often route deer around them, where you can find trails.

We have tried putting out cameras randomly, with dismal success rates. I left randomly located trail cameras out for as much as 3 years, and obtained only a handful of photographs, so that is certainly not a good idea.

Collecting and Processing Your Data

Once you have completed your trail camera survey of 10-12 days, collect your images on SD cards or in cell camera libraries for analysis. I like to “cull” my photos, by removing all non-deer images on my laptop or desk PC computer. You could do this as you review the photos, but I have found it is much faster to cull before you examine the photos. Then the work begins.

Using your computer, setup photo folders for each camera station labeling with either a station number or name. Then create subfolders with the following labels: Bucks, Does and Fawns. You can also setup a folder for interesting images or clips. What you will be doing is called “Sampling with Replacement;” in which you measure something, then return it to the population, where it can be chosen again in the process. You look through your photos one at a time, recording on a ledger, notepad or spreadsheet the number of does, bucks and fawns in each photo. This is NOT counting your deer, rather it is counting the frequencies in which they occur.

Now let’s take an example dataset to illustrate the process. Suppose you have finished all your photographs by station, and you have the following counts:

• 346 bucks
• 617 does
• 439 fawns

The first step is to determine your buck:doe ratio and doe:fawn ratio. To do so, we divide the number of doe photos by the number of buck photos, in this case 617/346= 1:1.78. So, there are almost two does for every buck on your property at the time of the census. Next, we divide the number of fawn photos by the number of doe photos to obtain the doe:fawn ratio; 439/617= 1:0.71. This also can be converted to a percentage fawn crop by multiplying by 100, which in this case means a 71 percent fawn crop. These are meaningful numbers in their own right, and very useful in making management decisions; however, it does not give you an estimate of the population number.

To accomplish this task, you go to your BUCKS folder and set up a series of subfolders representing each unique buck, giving him either a number or a name. My colleagues who do this kind of census have several ways of ending up with an accurate log of unique bucks. I start out with folders labeled by the number of mainframe points (2, 3, 4,….12, etc.); and, one labeled “Non-Typical.” Then I go through the photographs and pull-out bucks fitting each description. This will reduce the number of photos in each category to a more manageable number. Then, you select each folder and go through them to identify each unique buck.

It sounds laborious, but it is easier than you think. Pull the photos of each unique buck and store them in an appropriate subfolder. I understand there are several folks working on AI applications to do this, and I am hopeful it will significantly reduce the effort.

Let’s review what data we now have from our camera census. We have the ratios of bucks to does, does to fawns, and the number of unique bucks on the property at the time of census. Let’s suppose in the above study, we identified 17 unique bucks were on the property at that time. This is our “Key number.” If the buck:doe ratio was 1:1.78, then there are 1.78 does for every buck; which translates to 17 X 1.78= 30.26 does (rounded to 30).

And, if we now know we have 30 does and the doe:fawn ratio is 1:0.71, we have 30 X 0.71= 21.5 fawns (22). So, our estimated deer population is 17+30+22= 47 adults and 69 total deer.

This can all be a great deal of work, but the results have proven to be reliable and certainly useful in making management decisions. For larger properties, where there are larger numbers of deer, I conduct this detailed analysis every three years. In the interim, I still conduct the camera survey but only calculate the ratios.

This article does not exhaust all the uses for trail camera photos; it is only meant to provide you with a way to answer the age-old question: How many deer do we have? Hopefully, it’s useful and aids you in doing just that. Happy deer-counting!

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