Wildlife Damage Management, Internet Center for


Date of this Version

November 1976


Chemicals recently have been used to reduce bird damage in a variety of crops. One such chemical, 4-aminopyridine (4AP), first reported for this use by Goodhue, et al. (1964), was tested by De Grazio, et al. (1971, 1972) and was shown to be a safe, economical, and effective chemical for reducing blackbird damage to ripening field corn. Blackbirds ingesting 4AP emit distress cries and perform aerial displays that frighten other members of the flock from the field. An advantage of this method of reducing damage is that usually less than one percent of the blackbird flock ingest baits and become affected (De Grazio, et al., 1972). A logical extension for the use of 4AP would be in preventing blackbird damage to ripening sweet corn. On 27 June 1974, the Environmental Protection Agency granted a permit (No. 11649-EXP-3G) to test the effectiveness of Avitrol FC Corn Chops-991 (cracked corn treated with 3 percent 4AP and diluted with untreated cracked corn at a 1:99 ratio) in reducing blackbird damage to this crop. This paper reports the results of a study conducted in 1974 to evaluate aerially-broadcast 4AP baits to protect ripening sweet-corn fields from blackbirds. I am indebted to L. Baer and D. Stohr of American Fine Food, Inc., of Payette, Idaho, for providing data on field locations and history of bird damage, and to the many landowners who allowed me to use their fields. I acknowledge field assistance given by R. L. Martinez (Bureau of Plant Industry, Philippines), A. Ouattara (FAO trainee), and R. N. Smith (U.S. Fish and Wildlife Service). I thank coworkers of the Denver Wildlife Research Center--J. E. Peterson for analysis of the sweet-corn samples for 4AP residues; J. F. Besser and J. L. Guarino for assistance in planning this study; and A. H. Jones for review of the manuscript.