A QUANTITATIVE METHOD FOR EVALUATING AVIAN FOOD AVOIDANCE BEHAVIOR

Abstract

Food avoidance experiments could contribute to assessments of animals' behavioral responses to environmental toxicants. Food avoidance tests with mallards (Anas platyrhynchos L.) and northern bobwhite (Colinus virginianus L.) as the test species were patterned after avian 5-d dietary LC50 tests. Animals in each treatment group were given free access to untreated feed and feed treated with various concentrations of methiocarb (3,5-dimethyl-4-(methylthio)-phenyl methylcarbamate), a widely used bird repellent. Prior to food avoidance testing, 5-d dietary LC50 tests were conducted to provide baseline data for comparison. A measure of avoidance response was estimated from a log (dose)-probit (response) analysis. The percentage of total (treated plus untreated) feed consumption as treated feed consumption was the response variable. The detectable dietary concentration at which mallards and bobwhite began to avoid a specific contaminant was determined by calculating a median food avoidance concentration 50 (FAC50). In the absence of detectable avoidance behavior, test animals' total feed consumption can be expected to consist of equal amounts of treated and untreated feed. An effective avoidance index (EAI), LC50/FAC50, was used as a measure of a toxicant's “margin of safety.” Calculated results for methiocarb were as follows: for mallard, LC50 = 7,469 ppm, FAC50 = 145 ppm, EAI = 51.5; for bobwhite, LC50 = 827 ppm, FAC50 = 95 ppm, EAI = 8.7.