Proceedings of the Vertebrate Pest Conference

Red-winged blackbirds (Agelaius phoeniceus) have been discouraged from using cattle feedlots near Denver, Colorado, by baiting alleys with cracked corn treated with an aversion-producing immobilizing agent, DRC-736 [4-(methylthio)-3,S-xylyl N-methylcarbamate]. In three studies, large populations of redwings were reduced 70% - 98% within a few days and protection lasted about a month. In a fourth study, simultaneous baiting of three heavily used feedlots reduced redwing use by more than 90% within hours and was apparently responsible for these birds abandoning their roost and relocating in areas where they caused little trouble. Mortality was low (less than 5% of affected redwings in the fourth study), and few birds of nontarget species were affected.