R. J. Robbins 1 Considerations in the Design of Test Methods for Measuring Bait Shyness REFERENCE: Robbins, R. J., "Considerations In the Design of Test Methods for Measuring Bait Shyness," Vertebrate Pest Control and Management Materials: Third Conference. ASTM STP 752. E. W. Schafer, Jr .• and C. R. Walker, Eds., American Society for Testing and Materials, 1981, pp. 113-123. ABSTRACT: Data are presented to show that the ingestion of sublethal quantities of toxic bait can modify rodents' subsequent acceptance of that and other baits by way of two separate mechanisms: a learned aversion to that specific toxicant-bait combination and a nonlearned aversion to novel foods in general. A test procedure is offered which provides separate measures of the degree of bait shyness produced by these two mecha- nisms and which also avoids confounding the results with the direct effect of toxicant flavor upon bait palatability. KEY WORDS: vertebrate pest control, test methods, aversion, bait shyness, toxicants Illness-induced bait shyness is a problem frequently encountered in verte- brate pest control. The development of better and more sophisticated tech- niques for overcoming this difficulty would be greatly facilitated by the availability of a standardized procedure for evaluating the relative bait-shy- ness-inducing properties of different toxicants. Such a procedure should be capable of testing both for learned aversions to the flavor paired with illness and for nonlearned aversions to novel flavors in general, since recent work has shown that illness can produce flavor aversions through both of these mechanisms and since these different aversions pose individual problems in pest control. Learned aversions lead to the rejection of a previously accepted bait whereas nonlearned novel-flavor rejection (enhanced neophobia) could lend to the rejection of all subsequently applied baits. This paper will first present evidence which demonstrates the occurrence of both learned and nonlearned aversions. Then it will offer some considera- tions that apply to the design of a standardized procedure. Because the data presented below under "background experiments" have been discussed in 1 Assistant professor, Department of Zoology, Michigan State University, East Lansing, Mich . 48824. 113