Late summer is not just a stress period for wildlife, its also the time of year to survey white-tailed deer! If you regularly perform surveys on your property, you know the importance of conducting annual population estimates. For those of you that do not, surveys allow deer managers to get a snapshot of the local deer population just prior to hunting season. Without this information, it’s difficult to make harvest recommendations that fall in line with your management objectives.

The first piece of data you need going into the fall is a deer density estimate, or how many acres are available for each deer.  In central Texas, where I am located, a good rule of thumb is to 8 to 10 acres of good deer habitat per deer. Free-choice supplemental feeding can drop that to about 6 acres per deer, but one thing to keep in mind is that typically as deer density goes up the quality of individual deer goes down.

The best way to estimate deer density is to perform spotlight surveys. The information collected during spotlight surveys not only includes the number of deer spotted during the census, but also the amount of acreage that was actually observed during the survey. For example, if you have a ranch that is 1,000 acres, you can visually see 200 acres during your census, and you count 20 deer, then you have 100 deer on your property. Without good visibility data the spotlight count data will be worthless.

The next piece of the puzzle you will need to estimate your fall herd is to perform daylight observation surveys for deer. These are simple surveys because you can do them anytime you’re out on the property during daylight hours. And let me stress that although the data is easy to collect it can be of greatest importance! During daylight surveys simply record the number of bucks, does, and fawns observed each day. It’s that simple. But don’t guess! If you can’t tell what it is, don’t skew the data by guessing.

Oh, and you may be wondering why deer are surveyed during the late summer and into the early fall? Well, it’s because it’s at this time of the year that we can readily see deer, so that helps get the most accurate buck to doe ratio for a given area. In addition, essentially all of the fawns are born for the year and are moving around, so we can compare the number of fawns seen on our daylight surveys to the number of does to get a fawn crop estimate. 

Here’s an example: If you record daylight observations from August 1st to September 15th and you see 200 bucks, 400 does, and 200 fawns, then we can estimate the herd composition to be 1:2:1, or 1 buck for every 2 does and 1 fawn (25% bucks, 50% does, and 25% fawns). We can also estimate the fawning rate to be 50% since only 1 fawn was observed for every 2 does.          

Once fall deer population surveys are completed, deer managers can look at both the herd composition, density estimates, and the latest fawn crop to adjust the harvest rates to achieve their desired goals. Making a sound harvest recommendation is a science with a bit of an art thrown in since habitat conditions and fawn crops change annually, but collecting and analyzing deer survey data should be a part of proper harvest management.

Aircraft, including both helicopter and airplanes, can be effectively used to obtain deer density, sex ratios, fawn survival, and deer distribution information in some portions of the US. Although more expensive to conduct than the spotlight and mobile deer surveys, the aerial survey does provide the necessary population data in a short time frame. This information can be utilized to provide harvest recommendations for the entire ranch, as well as individual pastures. So, does a helicopter survey make sense for your deer management program?

The helicopter survey is considered by some to be the most accurate census for determining populations on a given unit of land. However, the total number of deer recorded on helicopter surveys should not be considered a complete count of all deer. Studies indicate that accuracy of helicopter surveys in South Texas brushland is fairly consistent, but they can underestimate deer density by 60-70%!

As a result, the information gathered from this type of survey should be used only as population trend information and for the preparation of annual harvest recommendations with the understanding that the deer density figures are probably conservative.

Helicopter Surveys

For aerial surveys using a helicopter, surveys should start approximately 15 to 30 minutes after sunrise. On ranches with dense vegetation and/or hills, it is recommended to start at least an hour or more after sunrise due to shadows. Of course, the drawback to starting later is that deer movement is reduced — so you need to keep some of these factors in mind and make sure that survey techniques are consistent over time.

On smaller ranches, or those located in open country, the entire ranch can be surveyed rather than sampled. The survey should be flown by pasture because this provides shorter transects and a good flight line can be maintained. Most often aerial surveys are conducted with both a pilot and an observer with each counting the deer observed.

The observer records all bucks, does, fawns and any unidentified deer spotted. This data should be recorded on a data sheet rather than a tape recorder as information may be lost due to tape malfunction or garbled due to aircraft noise. Data should be collected by pasture if a complete ranch survey is being conducted.

The observer may also record bucks by point-class (2-3, 4-7, 8-9, or 10+ points) to provide additional information. However, I wouldn’t suggest flying off from the transect to collect this information. If data is collected in this manner, then you can establish harvest ecommendations by pasture. This is an important consideration if the landowner or manager is leasing by pastures to several groups or otherwise needs to manage the harvest by pasture.

Ideally, transects should be flown on north-south bearings. This eliminates the observer and pilot from looking directly into the sun and missing deer. This is not always practical due to terrain or other obstacles that may be in the flight path. Another consideration is wind direction. Helicopter pilots prefer to fly into the wind when possible and the wind does not always blow from the north or south. Survey altitude will normally be from 30-50 feet above ground level. Flight altitude is also dependent upon terrain, vegetation condition, type, composition and any manmade obstacles that occur on the ranch.

Difficulties in locating and counting deer can be expected where heavy, close-growing stands of cedar, oaks and/or a combination of tall over story of trees with heavy brush undergrowth. Aerial surveys may not be suitable on ranches that have near complete canopy closure of evergreen species that reach heights of 10-15 feet. Shin oak, open ranches, or brush country is not as problematic because running deer are still readily visible.

In dense vegetation, deer will not readily move from the sound of the helicopter. For individual pastures it is better to initiate the count in the densest portion of the pasture and work toward the more open areas. Likewise the hillsides should either be worked from top to bottom or bottom to top depending on location of open areas.

Actually Counting

Veteran observers develop their own technique for counting deer. But all basically agree that an observer should not only look ahead but also scan to the side and to the rear of the helicopter. Also, in thick vegetation it is advisable to look through the vegetation rather than looking at the top of the vegetation.

Timing of aerial surveys is important. Ideally, deer population information is collected during late summer or early fall (August to November) to have the most current information when developing harvest recommendations. In areas where deciduous species are the dominant species, it is necessary to wait until after leaf drop (late fall/winter). Ranches with sparse vegetation may be surveyed as early as mid-August.

Permit Required

Before any aerial survey can be conducted, most states require that a permit form be filled out and submitted for approval. The owner of the helicopter must also be permitted by the state of the survey in order to operate this type of business.

Population estimation of white-tailed deer is an important cornerstone for the development of deer management strategies. However, estimating deer populations in heavily forested regions is difficult because of reduced visibility. Traditional survey methods, including spotlight counts and aerial surveys, provide limited results in dense forests. So now what?

The use of game cameras, or trail cameras, can provide photo records of an individual deer, a deer herd, and important parameters such as population estimates, sex ratios, and productivity. In an attempt to estimate a deer herd using game cameras, a census project was carried out in 2004 in the piney woods of east Texas, on a property 1,002-acres in size. A total of 7 cameras were placed out (1 trail camera per 150-acres) from September 2 to September 12.

A total of 158 photographs of deer were taken during that time. Twenty-three buck, 97 doe, and 48 fawn photos were collected/observed. Of the 23 total buck observations, 15 individual bucks were identified. The buck to doe ratio was calculated to be 1 buck:4.2 does (23 bucks:97 does). Since 15 individual buck photos were taken, 15 was multiplied by 4.2 to give a doe population size of 63 animals.

The doe to fawn ratio was 1 doe:0.50 fawns (97 does:0.49 fawns). The doe herd of 63 was multiped by 0.49 to put the number of fawns at 31 animals. Using the data/photos collected from the 7 game cameras, the total population of the 1,002-acre ranch was estimated to be 15 bucks, 63 does, and 31 fawns, for a total of 109 animals and a density of 1 deer/9.2 acres.

Their results concluded that buck-to-doe ratios were skewed, the fawn crop for that year was higher than average, and the deer density was above average. If this data is accurate, then recommendations should include continued doe harvest while limiting buck harvest to only mature bucks, if improving sex ratio and buck quality are a goals.

Their photos showed that most bucks photographed were 1 1/2 to 2 1/2 years old. Obviously, protecting these young animals will increase the number of mature bucks, improve sex ratio, and increase buck antler quality.

My Two Cents:

I think game cameras do have a place in deer surveys. However, there are a few problems with this particular study. First, the study takes place on an unknown population of deer. Granted, it’s very difficult to get an exact deer density, but I would like to have seen other population estimates based on the other survey methods mentioned previously.

In addtion, there is likely bias towards under-estimating doe and fawn numbers. Fall surveys under-estimate their numbers because of their smaller home range sizes. In addition, bucks tend to dominate limited food sources because of their larger body size.

Regardless, game cameras do provide valuable information on buck age structure, the progression of individual bucks over time, good estimates of fawn production, and provide trend data to monitor a deer herd over time.

Estimating the number of deer on your property is premium information for any deer manager. However, regardless of the type of census survey you use, some type of bias does exist. With this in mind, all surveys provide population trend data and some provide more precise data than others.

Today, we are going to talk about some of the pros and cons of performing aerial surveys for deer. In most cases when conducting aerial surveys for deer, helicopter will be used over airplanes (fixed-wing). With that said, helicopter and fixed-wing surveys allow the landowner and deer manager to determine the following:

1. Estimate the buck to doe ratio
2. Estimate fawn production
3. Examine antler development of bucks
4. Determine the distribution of deer on ranch
5. Examine the habitat condition of ranch
6. Determine the location of specific deer for harvest

Of course, the biggest drawback to a helicopter census is the cost. Increase costs in fuel, liability insurance and general maintenance, are passed on to the consumer — and that’s you. In addition, costs will also vary between operators, so look around before hiring someone to count deer on your coin.

The main benefit of a helicopter survey is that it is a time saving measure for landowners or managers that do not have the time to conduct spotlight surveys and herd composition counts.

Daylight observations are an ideal way to survey a white-tailed deer herd to determine the herd composition (sex ratios), reproductive success (% fawn crop), and the body condition of deer in a given area. Collecting daylight observations is an easy way to survey the deer herd on your property and data are easy to collect, often incidentally to other activities. Data collected during daylight observations should include sex (buck or doe), age (adult or fawn), and antler quality (number of points, spread, and anything else you can ascertain).

The best time to conduct daylight observation surveys is towards the end of summer and into early fall. In general from mid-August to mid-September is ideal because bucks have identifiable antlers, does are active and moving readily, and the majority of the fawn crop should be old enough to be active, be seen, and be recorded. In addition, this is a great time to collect daylight data because most hunters and land managers are out getting geared up for the upcoming hunting season. All you have to do is work up a data sheet or carry a notepad, carry a trusty set of binoculars and/or a spotting scope, and record animals observed while in the field.

Daylight observations can be collected a variety of ways. I recommend either walking or slowly driving property roads during the first and last two hours of daylight in the early morning or late evening or sitting in areas where white-tailed deer can be readily observed. All daylight observations should be used, but I suggest actively looking for deer in the morning and evening simply because they are more easily observed. Sitting around spin or supplemental feeders enhances the number of deer observations, but make sure to keep an eye out in all directions so that no deer are missed.

Feeders, especially protein feeders, tend to attract bucks and they will dominate the area immediately around feeders because of their aggressiveness and larger body sizes. At this point I will warn you because you are likely thinking that setting up a game camera at a feeder would be an easy way to collect herd composition data. However, because you now know that whitetail bucks dominate feeders — it should be realized that using photos from such areas will make you believe you have a higher percentage of bucks in the deer population than you actually have — so this will not necessarily work, but you can still use them if done properly.

Game cameras can be used, but I recommend using them in conjunction with walking and driving data, as well. If you do use game cameras (and I suggest digital game cameras), I recommend putting them along travel corridors and around water sources. This eliminates much of the bias (more bucks, surveys a smaller area) associated with placing cameras around feeding stations and will give you a better estimating on the percentage of bucks, does, and fawns in your deer herd.

Lastly, the more daylight observations you can collect the more faith you will put into your herd composition estimate. At minimum, you should record at least 75 observations, but a couple hundred would be much better and give you more confidence. Once you’ve collected the data, herd composition is easily calculated: