Computer simulation of a biomanagement system : the Mendocino County deer population in California

Abstract

Management of deer populations is directed toward multiple objectives. Deer populations on public and private lands belong to the public and thus management is a political process. Four components for an effective management system for deer populations are identified. These are the set of objectives relating to the resource, the set of regulations which will achieve the objectives, knowledge of the expected population response to alternative management strategies, and a means of monitoring these responses to determine whether or not the objectives are being achieved. Deer provide benefits mainly through the associated recreational opportunities and cause costs by interacting with land based economic activities such as agricultural crop production and reforestation. At certain times of the year deer may also compete with domestic livestock for forage. Deer also cause significant costs through collisions with automobiles on the highways. The extent of these benefits and costs, and others, is related to the biosystem through parameters such as the size and composition of the population, the extent of the hunting kill, and so on. In this thesis a computer simulation model of the Mendocino County, California, deer population is presented. The population is modeled as a density dependent birth and death process. Hunting strategies are potentially the most flexible management tool. Thus the model is structured to permit detailed examination of the response over time of the population to alternative hunting strategies. In California, a bucks-only hunting strategy has been followed since about the turn of the century. This study demonstrates that the bucks-only strategy neither effectively controls the size of the deer population, nor does it provide for the greatest recreational opportunities. The extent of the costs referred to above are directly related to the size of the population and the consumptive recreational benefits, that is those due to hunting, are directly related to the size of the hunting kill. Experiments with the model show that population control can be achieved and the hunting kill can be increased by a mixed buck and antlerless deer hunting strategy. Other results show that the computer simulation model can provide information about the biosystem which is not otherwise available. Simulation methods permit considerable insights into the operation and control of complex biosystems where the status of the systems is time dependent and the systems are influenced by uncontrollable elements so that at best the outcomes resulting from particular management actions are uncertain. The simulation model used in this study is applicable to other deer populations and other wildlife species

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