Simulation Experiments to Evaluate Alternative 

 Hunting Strategies for a Deer Population' 



F. M. Anderson,- G. E. Connolly^ 

 A. N. Halter,2 and W. M. Longhurst'' 



ABSTRACT 



A population dynamics model of the deer herd in Mendocino County, California, 

 is presented. Environmental influences are modeled as density dependent birth and 

 death rate functions. The computer program for this biomanagement model is outlined 

 and validity checks devised to improve the model are discussed. The output shows 

 the impact of selected hunting strategies on productivity, natural mortality, and 

 other population characteristics. Tests of hunting strategies related to alternative 

 management goals are summarized. Implications of computer simulation methodology 

 for the management of wildlife and fish populations are discussed. 



INTRODUCTION 



Management of a natural resource, such as 

 a deer herd or fishery, is the manipulation of 

 that resource and/or its environment in an 

 attempt to satisfy a set of objectives. The 

 objectives can be economic or noneconomic. 

 They may or may not be quantifiable, and 

 hence, the management problem may or may 

 not be solvable in the framework of "extremum" 

 problems. 



The management of a deer herd, like that 

 of a fishery, can be directed toward multiple 

 objectives. The deer herd may be maintained 

 at a particular level and age composition to 

 achieve a hunting kill having the greatest 

 value; alternatively, the herd may be main- 

 tained for purely aesthetic reasons. A multiple 

 objective of management may be to sustain 

 a certain deer density (deer per square mile) 

 at one time of the year to provide hunting, 

 or at another time of the year to provide 

 scenery for sightseers. 



Under certain environmental conditions, 

 managers may be prevented from knowing 

 whether or not the objective(s) has (have) 

 been attained. In areas of dense ground cover, 



' Technical Paper Number 2998, Oregon Agi-icul- 

 tural Experiment Station, Corvallis, Oregon. 



2 Department of Agricultural Economics, Oregon 

 State University, Corvallis, Oregon. 



3 Department of Agricultural Zoology, University 

 of California, Davis, California. 



managers must often resort to crude sampling 

 techniques to derive population estimates. 

 Other parameters can be readily measured. 

 For example, in a deer herd where hunting 

 is done only by license, the kill figures are 

 available soon after the hunting season, and 

 can be used in the formulation of subsequent 

 management strategies. It may be that certain 

 objectives will be satisfied if crucial parameter 

 values are between certain upper and lower 

 bounds. Alternatively, the objective of man- 

 agement may be to maximize the value of a 

 parameter. Examples of these two cases are 

 (1) to keep the average size of the herd be- 

 tween two values, and (2) to maximize the 

 annual hunter kill, respectively. Other paral- 

 lels to the objectives of management for a 

 deer herd can be found in the management 

 of a fishery resource. 



Both deer and fish populations are members 

 of complex, dynamic ecosystems. For each, 

 the age composition changes over time due to 

 the changes of such parameters as birth rates 

 and death rates. In addition to relatively 

 simple variability about these parameters, 

 changes in the population are compounded by 

 environmental changes. 



To illustrate, assume there is a functional 

 relationship between deer density and the 

 mortality rate of each age category. Further- 

 more, assume a fixed habitat structure and 

 that variability in the biosystem is introduced 

 only by changes in the weather. The effect of 

 these changes will usually be lagged. Other 



121 



