RESPONSES OF CAPTIVE BLACKBIRDS TO A NEW INSECTICIDAL SEED TREATMENT

Development of new repellent chemicals specifically to control crop da mage by birds may be cost-prohibitive. Instead, the use of compounds d eveloped for other pest control needs may be more practical. Thus, we conducted 2-cup feeding trials with singly caged red-winged blackbirds (Agelaius phoeniceus) and brown-headed cowbirds (Molothrus ater) to t est the repellency of a new seed treatment insecticide, imidacloprid ( proposed common name for Miles Incorporated NTN33893). Both redwings a nd cowbirds were strongly deterred (P < 0.05) from feeding on rice see d treated with imidacloprid at 620 and 1,870 ppm. When applied to whea t seed, imidacloprid effectively reduced (P < 0.05) consumption by red wings at rates as low as 165 ppm. We noted treatment-related effects s uch as ataxia and retching in some birds exposed to the highest treatm ent levels, but such effects were transitory. Videotapes indicated tha t imidacloprid was not a sensory repellent or irritant to birds. We co nclude that avoidance of imidacloprid-treated food is a learned respon se mediated by postingestional distress. Although developed and envisi oned as a broad spectrum, systemic insecticide, imidacloprid also appe ars to have promise as a bird repellent seed treatment.