Mint plant derivatives as blackbird feeding deterrents

Naturally occurring 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 (Agelaius phoeniceus) more effectively than methyl anthranilate. Furthermore, pennyroyal oil, from which pulegone is obtained, was nearly as effective as pulegone itself. Brown-headed cowbirds (Molothrus ater) were more sensitive to pulegone than were redwings, but female boat-tailed grackles (Quiscalus major) were less sensitive. Because pulegone produces both sensory irritation and post-ingestive distress, it has potential for seed treatment and other bird deterrent applications.