Population Dynamics and Estimation of Maximum Sustained Yield (MSY) in a Black-Tailed Deer Population

Abstract

The population characteristics of a free-ranging deer (Odocoileus hemionus columbianus) population in western Washington were studied from 1979 to 1989 to determine the impacts of sport hunting on the dynamics of the deer herd. Annual measurements of relative population density, age-specific reproductive rates, sex and age structure, harvest rates, and hunting effort have been used to understand the response of the deer populations to different harvest rates and resultant changes in deer density. A sustain yield (SY) curve was empirically derived from the 10 year data set, and compared with a theoretical curve, based on the logistic model. The SY curve derived from the data set indicated a higher maximum sustained yield (MSY) than the theoretically derived MSY value. The latter MSY was taken from a population at approximately 50% of carrying capacity, while the former was taken from a population at approximately 75% of carrying capacity. These observations are likely the result of the highly nonlinear relationship of reproductive rates and population density, which was also derived from the data set. The population dynamics model is now being applied to other deer herds for extensive field testing.