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Trapping records from studies conducted in Hawaiian sugarcane fields were analyzed to determine the effects of rat captures on subsequent capture success of Rattus norvegicus, R. rattus, and R. exulans. Traps that captured rats were subsequently more likely to capture another rat of the same species. We detected no differences in trap responses of males and females, nor did we observe any evidence that capture success of Polynesian rats and roof rats was affected by previous captures of Norway rats. This increased trap success may have been due to residual trap odors, or to greater success of traps set in optimal locations. Researchers should exercise caution in interpreting trapping results, and take precautions to eliminate residual trap odors due to previous captures. A better understanding of the effects of congeneric odors on the trapability of rats could lead to the development of more attractive and selective bait formulations, improved trapping techniques, and better interpretation of research results.