U.S. Department of Agriculture: Animal and Plant Health Inspection Service
Date of this Version
1-2011
Citation
National Sunflower Association Sunflower Research Forum, January 11-12, 2011. Fargo, ND. NSA Website Online Forum.
Abstract
Red-winged Blackbirds (RWBL) and Common Grackles (COGR) are the two most abundant blackbird species on the continent; Brewer’s Blackbirds (BRBL) are a much less common, but closely related species, and along with European Starlings (EUST), they are two of the most common groups of birds in North America, with combined populations that reach into the several hundreds of millions; making up a significant portion of the avian population. Although one of the most common birds on the continent, certain regions have seen declines in RWBL for a number of decades. In Ohio and North Dakota, this has been attributed to certain agricultural practices. Population sizes of Rusty Blackbirds, a related species, have also been on the decline for some time due largely to habitat loss, while populations of COGR, BRBL, and EUST are either stable or increasing.
Despite the decline of the RWBL in certain areas, farmers continue to endure annual monetary losses to depredation by these crop pests. In some areas, complaints of blackbird depredation have increased, giving impressions that populations in those areas are on the rise instead of decline. Damage to sunflower has been estimated at 2-4% of the value of the crops, or approximately $4-$11 million dollars. Yearly losses to corn and rice growers in the US are even higher, estimated at $25 million and $21.5 million respectively. A better understanding of blackbird population trends and how and where populations select wintering roosts would permit quicker responses and reduce the costs of identifying and managing roosts for the purposes of resource protection, and disease outbreak prevention.