Why tracking your sightings after every hunt matters...

Deer observation data provides some of the most useful information that can be collected by those participating in a QDM program. When properly collected and analyzed, observation data can reveal important details about the herd’s population size, sex ratio, fawn recruitment, age structure, and overall co-op management success. Since relatively few bucks are harvested in many QDM programs, observation data, particularly on bucks, can be even more useful than harvest data.

The most important aspect of collecting good observation data is consistency. Data must be collected the same way each year and compared only to observation data collected during the same period in future years. When collecting observation data, count every deer you see during each outing, even if you have seen the same animal during a previous observation period. This means the same animal may be counted several times during a season. This is fine because the purpose of the observation data is not to count every individual deer on the property, but rather to determine the relative abundance of deer and the proportion of bucks, does, and fawns. Unless you can positively identify the deer as a buck, doe, or fawn, record it as "unknown". Do not guess. A small amount of reliable data is better than a large amount of data containing numerous misidentified animals.

Our co-op can use the observation data to estimate the following attributes of our deer herd:

• Relative Abundance

• Sex Ratio

• Fawn/Doe Ratio (Fawn Recruitment)

Relative Abundance

Observation data can be used to estimate the relative size of the entire deer herd and as well as the relative abundance of a specific segment of the herd such as the abundance of bucks with an antler spread >14". Data is reported in terms of the number of deer observed per hour. This is how the data is equalized from year to year and is why maintaining an accurate log on the number of hours in the field is important. It is how we maintain a year-to year comparison that is "apples to apples". To calculate an "index" for comparison to future year’s data of the relative size of the deer herd on a specific property or in our co-op as a whole, we simply add all of the deer observations for a given year, and divide this number by the total number of hours spent observing deer.

For example, if the combined hours spent observing (hunting) by all of the members within our co-op was 500 hours during this year’s hunting season and during this time a total of 300 total deer observations were recorded, we divide 300 (deer) by 500 (hours) and get a sighting index of 0.60 deer per hour of observation within our co-op. On a smaller scale, if hunters on an individual property logged a total of 40 hours observing a total of 30 deer, we divide 30 (deer) by 40 (hours) and get a sighting index of 0.75 deer per hour of observation. This example might suggest to a property owner/hunter that their particular property may have a slightly higher deer density than the average density of the co-op as a whole.

By comparing general deer sighting ratios between adjacent properties you might learn that your overall deer sighting ratio, or deer density is well above, or below that of your neighbor. Habitat considerations being equal, you might for example, then learn by talking about the data with your new friend and co-op member neighbor that they utilize food plots to hold the deer close to their property’s core area. You would then at a minimum better understand the difference in deer sightings between you and your neighbor, and in fact may choose to utilize food plots or implement some other strategy such as habitat improvement to increase the number of deer you observe on your property in future years. This type of informed herd management decision would likely not be possible without the reliable data gleaned from a deer observation log program.

Sex Ratio

The sex ratio of a herd is defined simply as the ratio of females to males. The adult sex ratio is the ratio of adult does (1 ½ years old +) to adult bucks (1 ½ years old +) in the herd. This ratio is determined by dividing the total number of adult doe observations by the total number of adult buck observations.
For example, 140 adult doe observations divided by 70 adult buck observations would result in a 2:1 doe to buck sex ratio.

This data is important to us because based on the data generated, an informed decision can be made regarding the number of does that should be harvested each year. For example, if the sex ratio were 3 adult does to 1 adult buck, we might consider attempting to harvest more does. Conversely, if the ratio was something closer to 2:1 or even 1:1, we might consider reducing the emphasis on harvesting adult does until and unless the ratio widens.

Fawn:Doe Ratio (Fawn Recruitment)

The fawn:doe ratio is simply the average number of fawns per adult doe (1 1/2 + years old) in the herd. The data collected can provide a useful estimate of “fawn recruitment”, which is the number of fawns that have survived long enough to be “recruited” into the fall hunting population. The fawn recruitment ratio is calculated by dividing the total number of fawn observations by the total number of adult doe observations.

For example, 180 fawn observations divided by 280 adult doe observations would result in a fawn recruitment of 0.64, or a little more than 6 fawns per 10 adult does. Fawn recruitment is an important indicator of the general nutrition level and overall health of the herd as fawns may be still-born or born too small to survive more than a few days due to the general poor condition of the mother doe. Another reason that this number can be useful to us is because it can be an indicator of year-to-year swings in fawn mortality due to predators. This is why there are field the observation form for coyotes, bears, and bobcats.

Some of the highest recruitment rates nationally are around 1.2 and are found in areas of relative low deer densities and good nutrition and soils such as in Illinois and Iowa. Some of the lowest recruitment rates are found in states like Oklahoma and Arizona with sub-par habitat and are around .50. Overall, rates in the area of .80 are considered average and New York would generally fall into this range. It is important to keep in mind that the above rates are state-wide averages, and individual WMU’s and properties can and do vary significantly. More importantly, fawn recruitment rates can be affected and improved by individual members and property owners through the implementation of sound whitetail management practices.