How deer harvests are calculated

It's that time of year again when hunters begin to wonder how the state's deer harvest is going. If a hunter has shot a buck, seen a few deer and heard lots of shooting, he or she probably thinks the harvest is high. If the converse is true, the hunter thinks that the deer kill must be low. Fortunately, the state has a much better way to arrive at an accurate harvest estimate.

Last week at the Huntingdon bear-check station, I overheard a hunter ask Pennsylvania Game Commission biologist Justin Vreeland how the Game Commission calculates the deer harvest. To Vreeland's credit, he smiled and answered the question as if he had never heard it before.

The answer is simple, but still misunderstood and questioned by a certain segment of the hunting fraternity. Maybe it is my biology background that gives me a different perspective, but the commission's method is logical, accurate, and straightforward — and it makes total sense to me.

In Harrisburg, the Commission tabulates the harvest by counting the report cards mailed in by hunters, as well as the Internet postings and the deer reported by telephone. Even with three easy ways to report, considerably less than half of the state's hunters report their kills.

Each year, the commission sends at least 30 teams of "deer agers" into the field during the deer seasons — a monumental and expensive undertaking. The teams visit deer processors where they count, sex, and age deer that are being butchered. They also record the hunter information, wildlife management unit, county, township harvested and other data — but let's look at just the basic factors.

The deer teams check about 25,000 deer each fall — no small sum. The large number is necessary to gauge the age structure of the deer population and to arrive at an accurate harvest estimate. Processors are visited in each management unit.

The deer physically checked are compared to the deer reported by hunters. For example, if 10,000 of the 25,000 tagged deer that were aged at butcher shops show up as deer reported to Harrisburg by hunters, that reflects a 40 percent reporting rate [10,000/25,000 = .40].

Now, let's say that, for the 2010-11 seasons, the number of bucks reported to the Game Commission was 49,200. With a 40 percent reporting rate, those 49,200 bucks now represent 40 percent of the total harvest. Therefore, if 40% = 49,200, then 100% (or the total buck harvest) would be calculated to be 123,000.

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Please note – I made the above deer harvest calculations as simple as possible. Actual reporting rates vary for antlered and antlerless deer, and by management unit, so the commission's real calculations are slightly, but only slightly, more complicated. The actual Game Commission calculations for last season can be found at www.pgc.state.pa.us.

All estimates contain a plus or minus factor that includes the element of chance in the calculation. The larger the number of deer checked at butcher shops and the higher the number of deer reported by hunters, the smaller the possible error in the calculations. So, if you, as a hunter, want to make the commission's estimates as accurate as possible — be sure to report your deer kills.

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Age is another very important thing that the wildlife biologists look at in the harvest. For example, if the PGC is attempting to stabilize the herd and younger antlerless deer begin to make up a larger percent of the harvest — then that would indicate an overharvest of antlerless deer.

Last season, the deer-check teams found that 52 percent of the buck harvest was made up of bucks 2.5-years-old or older. According to the commission, that is the highest percentage of older bucks harvested in the last 30 years. It is also proof in my book that antler restrictions are working.

By the way, the commission's method of estimating the deer harvest has been peer reviewed and validated as sound science. In other words, biologists from other states have studied the agency's methods and found them to be proper and accurate.

Meanwhile back at the bear-check station …

Later that afternoon, I complimented Vreeland for his explanation about the deer harvest calculation. He shared that he has never been questioned about the bear calculation.

"Why is it that we use almost exactly the same formula to calculate the bear population as we do the deer harvest and no one ever questions the bear data?" he remarked to me.

Here's something to ponder — a bear hunter might spend 10 years or more hunting bruins and never see a hair, maybe 20 years hunting and never bag a bear, yet bear hunters never question the commission's estimate of the bear population.

Odd, isn't it?