Influence of Simulated Harvest on Iowa Wild Turkey Populations

Abstract

Computer models were used to simulate autumn harvest of a wild turkey (Meleagris gallopava silvestrus) population in Iowa. Parameters were based on estimates of survival rates, fecundity rates, and age and sex ratios from field studies in mixed forest-farmland from 1977 to 1981. Simulations with average survival and fecundity parameters resulted in a population growth rate of 4% per year. If female survival rates were reduced 4.8% or fecundity was reduced 13.9%, the population became stationary. Interaction of hunting and non-hunting mortality was incorporated according to 3 hypotheses: additive, completely compensatory, and compensatory mortality rates up to a threshold. Estimated allowable autumn harvest rates, based on the goal of a stationary breeding population, ranged from 4.7% to 9.5 % of the females and from 14.8% to 28.4% of the males. At these harvest levels, female survival would have to increase approximately 5% and fecundity 16% to compensate for the harvest and return the population to former growth rates. The time required for the total population to decline by 25% of present levels ranged from more than 100 years at 5% harvest rate under additive mortality to almost 74 years at 10% harvest rate under the threshold theory

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