REDUCING BIRD REPELLENT APPLICATION RATES BY THE ADDITION OF SENSORY STIMULI

Red-winged Blackbirds (Agelaius phoeniceus) cause substantial damage t o a variety of crops throughout North America. Nonlethal methods for c ontrolling damage are generally ineffective, and environmental and cos t concerns have limited the availability of chemical repellents such a s methiocarb. One means of potentially lowering the effective applicat ion rate of methiocarb and similar aversive compounds is by combining the treatment with sensory cues. We tested groups (n=4) of male Red-wi nged Blackbirds in a series of 4-day feeding trials using brown rice t reated with 0.025% (g/g) methiocarb, five times less than the previous ly established effective bird repellent rate. Each methiocarb treatmen t suppressed rice consumption, whether the repellent was alone or comb ined with a visual (red dye) and/or volatile (methylpyrazine) cue. Whe n rice treated with just the sensory cues was subsequently presented, the red dye, but not the methylpyrazine, continued to deter feeding on rice. These results show that postingestive chemical repellents such as methiocarb can be effective al reduced rates provided the repellent is paired with an aversive Visual cue. The addition of aversive stimu li may be particularly useful in reducing damage to seeded crops and i n protecting birds from incidental ingestion of toxic granular pestici des.