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Killing the Factory?

Posted Sep. 1, 2001

While fraternizing within deer hunting circles, have you ever heard the saying, If you shoot does, you kill the factory? If so, you can bet the person who says that doesn't know much about deer population management. The next time you hear people make that statement, ask them if they know the deer population density, fawn crop, and buck : doe ratio on their property. Also, you may find their response interesting if you ask them how much time they think it would take to harvest a doe with a bow, black-powder rifle, or modern rifle.

In southern Oklahoma and northern Texas, it would be unusual for shooting does to kill the factory. If a doe is shot, she sure won't be producing any more fawns, but the deer population as a whole responds differently. The only way to monitor this response is to collect data on estimated deer numbers, buck : doe ratios, and fawn crop, which is also called production. Over time, this information can be used to look at deer-herd trends that help determine the effects of doe harvest.

The table depicts deer population information collected on the Walnut Bayou Deer Management Association (WBDMA) property.

The WBDMA is in Love County, Oklahoma, and one of its goals is to balance deer numbers with habitat quality by increasing doe harvest. Deer numbers on the WBDMA exceed the number desired to improve deer quality, i.e., body weight and antler growth. Doe harvest increased since 1996, yet estimated doe numbers also increased from 1996 to 1999, dropping only slightly in 2000 (figure 1).

It's unclear whether the slight decline in doe numbers is due to harvest pressure, imprecision of the spotlight survey technique, recent drought and its relation to habitat conditions, or other variables. The WBDMA includes 12,500 acres, so the 2000 doe harvest represents one doe for every 147 acres. Future harvest and population data will help us determine an adequate doe harvest quota, but it may take a harvest of one doe for every 100 acres, or 125 does, for deer numbers to begin to decline.

Such a harvest is a substantial undertaking, considering the amount of effort involved in harvesting a doe. Most deer hunters think it's easy, which may be true if they harvest only one doe every year, but what if they are trying to achieve a doe harvest quota? Information collected from hunters willing to shoot a doe at every legal opportunity on the Coffey Ranch was analyzed to assess the effort involved in harvesting does. Keep in mind that these data are a good estimate of how much time it takes to harvest a doe but do not include all of the time involved with field dressing and processing. On average it took 49 hunts to harvest a doe by using a bow, 15 by using a black-powder rifle, and 8 by using a rifle (figures 2, 3, and 4).

Hunts averaged about three hours each. Another way of looking at it would be that doe harvesting takes, on average, 147 hours with archery equipment, 45 hours with black-powder equipment, and 24 hours with a modern rifle. Also note that in general, as doe numbers increased, harvest efficiency increased, and vice versa.

Let's apply these numbers to the WBDMA's goal of harvesting 125 does. It would take an average of 6,125 hunts, 74 hunts per day, or one hunter on every 169 acres each day of Oklahoma's 83-day archery season to harvest 125 does. It would take about 1,875 hunts, 208 hunts per day, or one hunter on every 60 acres each day of our 9-day black-powder season. And because our enrollment in the Oklahoma Department of Wildlife Conservation's Deer Management Assistance Program allows 16 days of antlerless rifle harvest opportunity, it would take about 1,000 hunts, 63 hunts per day, or one hunter on every 198 acres each day.

Considering current deer population levels, hunting season structure, and the amount of effort it takes to harvest a doe, legally harvesting enough does to kill the factory would be difficult even for serious deer managers.

A detailed report about the Walnut Bayou Deer Management Association is available on www.noble.org) or by mail from our publications distribution department.