Antler Points

It is difficult to see many deer in the field. Trying to get very large data sets to gain confidence in the numbers year after year is difficult, especially for deer that are often trying to prevent you from adding them to your data.

The age of deer can be estimated by many techniques (tooth wear, eye lens weight, etc.), but in the field the only difference in which observers can feel confident is between fawns and adults. Oh, you can guess that a small dear may be a yearling, or guess that the glimpse of a running deer was of a small deer-but these are not the numbers needed for sophisticated deer herd management. Hunters and observers may guess, enter data, analyze it, then realize that they can draw no conclusions. This is wasted effort! If you know before you start that no good will result in the end from such work ... then don't do it.

Over the years I have recommended a practice called "simulation." It is simply to makeup about 50 observations that are reasonable and in the ballpark. Then analyze them as if they were real. The learning process is great, the analytical programs can be saved, and the useless numbers can be scrapped. When you do go to the field to get real numbers you do not waste time or effort, you concentrate on high quality needed numbers, and you can produce a report instantly ... because most of the hard thought has already occurred on the hypothetical data. Many a deer researcher has a flat forehead from slapping themselves there as they say, "Oh, if I had only realized I did not need that data!" (or needed that other data). It is a recommendation ignored for years but I persist, partially because taking the recommendation is now very easily done with standard spreadsheet computer programs.

So, a group of hunters goes out into deer range throughout the year near their camp. They see 60 fawns, 50 does. The fawn:doe ratio is 120:100 or 12 per 10 does. One problem arises for the analyst or just anyone trying to attach some meaning to these numbers: antlerless buck or doe? Timing of record keeping is critical. A large number of antlerless bucks can "dilute" the count-one usually seeking to express the number of fawns produced per doe (as an index to herd productivity).

A convenient index is:

bucks:does:fawns

where all are standardized to 100 does. Thus, the conventional sex ratio of males:100 females is available at the left; an apparent production index or doe-to-fawn ratio is available to the right. The right-hand side is probably better estimated than the left-hand side.

Where 23 bucks, 60 does, and 70 fawns have been observed, then the ratio, combining sex and gross age (adults to the left, fawns, right), is

38:100:117

A program of The Deer Group is available for these simple observations. Not necessarily because the arithmetic is simple, it may help when many weeks of observations are studied or when data over many areas are studied. It is useful, simply in learning the concept.

The ratio, whatever it is, will change tomorrow. Not only are the numbers difficult to get. They are temporary estimates of a real relationship.

For a population to be stable, that is, to have an approximately a zero rate of change, the number of produced fawns must equal the number of animals dying. If an adult:fawn ratio is 100:30, then harvest and other mortality must be about 30% in a stable population. That means that the 70 left after mortality occurs must be able to produce another 30 next year. Depending on the sex ratio (the proportion of does) and how many of them are young and non-breeding, this might be possible.

The combination of sex and age information gives hunters insight into which direction a herd may be going. Based on objectives and available resources, that direction can be guided by the sophisticated, modern manager of the wild deer herd.

This Web site is maintained by R. H. Giles, Jr.
Last revision January 17, 2000.