Date of this Version
One of the most widespread bird problems in the Western United States is damage to ripening cereal grain crops. Crops such as corn, rice, and sorghum, when grown close to favored roosting areas are often subject to serious damage from large flocks of feeding blackbirds. The redwinged blackbird is the most numerous species and causes most of the damage, but other blackbird species, including the yellow-headed blackbird, the common grackle, the brown-headed cowbird, and Brewer's blackbird, also contribute to damage problems. The Denver Wildlife Research Center is actively investigating methods to combat blackbird depredations to field corn in the vicinity of Sand Lake National Wildlife Refuge in northeastern South Dakota. This report will deal with this particular project since it is the Denver Center's most active study involving blackbird depredations. The Sand Lake project was initiated in 1960 and was planned for five years. Field work usually begins in April and ends in October. The major work period is August and September, the time of peak populations of birds and of the most acute damage.