Effects on wildlife of at-planting corn applications of granular carbofuran

Application, at planting, of a granular formulation of the insecticide carbofuran to 195 ha of corn resulted in wildlife mortalities in Frederick County, Maryland, in April and May 1980. Systematic field searches within 96 hours of treatment revealed six dead songbirds (order Passeriformes), five of which contained residues of carbofuran ranging from 1.6 to 17.0 ppm (gastrointestinal tract and liver combined). An American robin (Turdus migratorius) and a mallard (Anas platyrhynchos) were observed exhibiting symptoms consistent with carbofuran poisoning. A dead white-footed mouse (Peromyscus leucopus) found 24 hours posttreatment contained 15.1 ppm carbofuran. The pesticide was detected in 10 of 12 common grackles (Quiscalus quiscula) shot at the site (gastrointestinal tract and liver: x̄ = 0.75 ppm, SE = 0.19), suggesting extensive sublethal exposure among birds feeding in treated fields. Captive house sparrows (Passer domesticus) and red-winged blackbirds (Agelaius phoeniceus) were orally administered carbofuran granules; doses as low as one granule resulted in fatalities with both species. Given the extensive annual use of granular carbofuran (>4 × 106ha) in the United States, numerous wildlife mortalities are likely.