The Extermination of Animal Populations by Artificial Predation and the Estimation of Populations

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Abstract
Artificial predation is defined as a predator-prey relationship in which the predator is man. Examples from the literature are given in which artificial predation was successful, in the sense that the prey species was exterminated or nearly so, and other examples in which it was unsuccessful. It is shown on theoretical grounds that reduction of a prey population by means of artificial predation would be expected to follow a geometrical progression; in several examples from the literature this expectation is fulfilled. In an experiment in which a population of tsetse flies was subjected to artificial predation the geometrical expectation was fulfilled closely. In this same experiment by summing the geometric series, it was possible to estimate the initial prey population and birthrate of tsetses. These estimates agreed well with independent estimates made before the start of artificial predation by the method of releasing and recapturing marked flies. The element of immigration, included in the birthrate in both methods of estimation, was shown to have a low numerical value which was negligible when the population was large, as at the beginning of the experiment, but was big enough to prevent the artificial predation proceeding to extermination.