Effects of Organophosphate Insecticide Application to the Conditioned Taste Aversion of Red-winged Blackbirds, Agelaius phoeniceus, Icteridae

An experiment was conducted among free-ranging red-winned blackbirds (Agelaius phoeniceus) that acquired illness-induced conditioned taste aversion (CTA) by consuming insect prey tainted with a dose of parathion up to 2.0 mg/kg consumer body weight. Birds quickly acquired CTA and avoided all four insect prey during a lengthy posttest without parathion. This experiment proved that organophosphate insecticide application in the field might decrease the food consumption of wild birds and may also affect the reproductive success of breeding birds. Thus, CTA acquired accidentally after eating insecticide contaminated insect prey appears to be one of the reasons for the decreasing number of breeding songbirds in North America.