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Determining Economic Value of Crops, Livestock and Other Marketable Items

Monetary losses caused by wildlife can be directly measured in some cases. For example, if a certain number of bushels of corn are damaged (lost) due to bird depredation and the value of a bushel of corn is known, then total losses can be determined. To assess whether employing a bird management practice is cost effective, one only needs to add up the cost of the management action (traps, repellents, frightening devices, labor, time etc.) and compare the cost of the management action to the value of the crop being saved. If the crop saved value is more than the management cost, then management is cost effective.

As an example of the above, Dr. Shwiff of the USDA's National Wildlife Research Center, looked at blackbird depredation on rice and at the economics of using a particular type of trap to catch the blackbirds. First, Shwiff needed to know how much damage each individual blackbird causes to rice. From previous studies, an estimated figure was available. Shwiff then calculated benefits of the management action, which in this and may other cases becomes "damage abated" or damage prevented. Calculations suggested that to use the bird traps in question, an impossible number of birds would have to be caught and removed to make the management action cost effective. The birds simply weren't causing enough damage to justify using this method. In this case, economics was used to guide and refine what methods to use - not to decide whether management is used at all.

Another problem is coyote predation. Predation on livestock, and control of that predation, are very public issues. Thus, coyote management is being looked at closely as to whether management actions are cost effective.

For example, in a recent study, Shwiff was asked to look at the effects of the recently legislated California trap ban. When the ban went into effect, it meant fewer techniques were available to control coyotes. Was there an economic effect? Usually when managers have 10 tools and lose 2, that implies some shift in cost. Factors studied included whether replacement management methods took longer to use (i.e. more labor time) and whether alternative traps were more expensive to build.