Crowell and Pimm, and Schoener have independently suggested an indirect method to measure interaction coefficients in the field. We tested the method in the field by comparing the interaction coefficients estimated by the indirect method with those measured directly in manipulation experiments of bumblebee densities. The method failed to detect the considerable negative effect of the density of B. flavifrons on B. rufocinctus which was observed in the manipulation experiment. The present study questions the validity of the method and advises ecologists not to use it before testing it more rigorously.
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Abramsky et al. (1986) studied this question.