ACEPHATE AFFECTS MIGRATORY ORIENTATION OF THE WHITE-THROATED SPARROW (ZONOTRICHIA-ALBICOLLIS)

Migratory white-throated sparrows (Zonotrichia abicollis) were exposed to acephate (acetylphosphoramidothioic acid O, S-dimethyl ester), an organophosphorus pesticide, to determine its effects on migratory orie ntation and behavior. Birds were also exposed to polarizer sheets to d etermine the mechanism by which acephate may affect migratory orientat ion. Adult birds exposed to 256 ppm acephate a.i. were not able to est ablish a preferred migratory orientation and exhibited random activity . All juvenile treatment groups displayed a seasonally correct southwa rd migratory orientation. We hypothesize that acephate may have produc ed aberrant migratory behavior by affecting the memory of the migrator y route and wintering ground. This experiment reveals that an environm entally relevant concentration of a common organophosphorus pesticide can alter migratory orientation, but its effect is markedly different between adult and juvenile sparrows. Results suggest that the survival of free-flying adult passerine migrants may be compromised following organophosphorus pesticide exposure.