Date of this Version
Damage to corn by blackbirds (Icteridae) has been an economic problem throughout historical times in North America. Ohio, with the highest nesting season population density of red-winged blackbirds (Agelaius phoeniceus) in North America and large acreages of corn, has been a key state in this conflict. Survey of damage from 1968 to 1979 revealed that blackbirds annually destroyed less than 1% of the corn crops in Ohio, a 4- to 6-million dollar loss at 1979 prices. This total dollar loss is somewhat misleading because of the uneven distribution of damage among fields. Over 97% of the cornfields in Ohio receive less than 5% loss and these losses make up about 60% of the total loss in the State. Damage control efforts need to be primarily directed toward the remaining 3% of the fields that often incur losses greater than 5% and constitute about 40% of the total loss in the State. Most of these fields are located within 8 km (5 miles) of the marshes containing concentrations of roosting birds in late summer. Successful programs to reduce damage must use one or more of a series of management measures, integrated with normal farming practices. The selection of management measures should be based on assessments of amount and type of bird damage likely to occur in a field and constraints imposed by farming practices. Management recommendations include (1) planting of hybrids with ear tips well covered by husks; (2) reduction of weed and insect populations to make the field less attractive to birds; (3) judicious use of mechanical frightening devices or a chemical frightening agent at the time birds initially damage the maturing corn; (4) the provision of natural or planted food and cover sites outside the corn; and (5) harvesting the crop, especially sweet corn, as early as possible.