U.S. Department of Agriculture: Animal and Plant Health Inspection Service


Date of this Version

December 2002


(Resource publication-United States, Fish and Wildlife Service ; 136) Includes bibliographical references. Supt. of Docs. no.: 149.66:136 1. Corn-Diseases and pests-Ohio. 2. Red-winged blackbird-control- Ohio. 3. Grackles-Control-Ohio. I. Title. 11. Series: United States. Fish and Wildlife Service. Resource publication-United States, Fish and Wildlife Service ; 136. S914.A3 no. 136 [SB608.M2] 333.95'4s [633.115968864] 80-607007


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. Surveys 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.