AbstractFood and water avoidance experiments were conducted on mallards (Anas platyrhynchos L.) and northern bobwhite (Colinus virginianus L.) exposed to a range of dietary carbofuran concentrations. A dietary avoidance concentration 50 (analogous to an LC50) was calculated for each avoidance experiment. This statistic describes the dietary toxicant concentration threshold at which, when exceeded, exposed animals are likely to discriminate between untreated and treated feed or water. The food avoidance concentration 50s (FAC50s) for mallards and bobwhite were 10 and 159 ppm, respectively. The water avoidance concentration 50 (WAC50) for mallards was 3 ppm. For bobwhite the WAC50 for carbofuran was estimated to exceed 50 ppm.