Naturallyoccurring plant constituents are potentially useful as avian feeding deterrents. In a series of cage trials, pulegone, a compound found in various species of mint, suppressed consumption of rice seed by red-winged blackbirds (Agelaiusphoeniceus) more effectively than methyl anthranilate. Furthermore, pcnnyroyal oil, from which pulegone is obtained, was nearly as effective as pulegone itself. Brownhcadcd cowbirds (Molothrus arer) were more sensitive to pulegone than were redwings, but female boattailed grackles (Quisculus major) were less sensitive. Because pulegone produces both sensory irritation and post-ingcstivc distress, it has potential for seed treatment and other bird deterrent applications.Published by Elscvicr Science Ltd.