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IMPACT OF BLACKBIRD DAMAGE TO SUNFLOWER: BIOENERGETIC AND ECONOMIC MODELS
USDA National Wildlife Research Center - Staff Publications
  • Brian D. Peer, Department of Biological Sciences, North Dakota State University, Fargo, North Dakota 58105 USA
  • H. Jeffrey Homan, USDA National Wildlife Research Center, Great Plains Field Station, 2110 Miriam Circle, Bismarck, North Dakota 58501 USA
  • George M. Linz, USDA National Wildlife Research Center, Great Plains Field Station, 2110 Miriam Circle, Bismarck, North Dakota 58501 USA
  • William J. Bleier, Department of Biological Sciences, North Dakota State University, Fargo, North Dakota 58105 USA
Date of this Version
2-1-2003
Comments
Ecological Applications, 13(1), 2003, pp. 248–256 Copyright 2003 by the Ecological Society of America.
Abstract

We constructed bioenergetic and economic models to estimate the potential impact of Red-winged Blackbirds (Agelaius phoeniceus), Common Grackles (Quiscalus quiscula), and Yellow-headed Blackbirds (Xanthocephalus xanthocephalus) on production yields of sunflower in the northern Great Plains of North America. The amount of sunflower consumed annually by males and females, after considering field metabolic rates, energy value and moisture content of achenes, and percentage of sunflower in diets was, respectively: Red-winged Blackbirds 277 g and 168 g; Common Grackles 267 g and 230 g; and Yellow-headed Blackbirds 248 g and 139 g. The per capita annual economic damage was: male Red-winged Blackbirds $0.09 (U.S. dollars), females $0.05; male Common Grackles $0.09, females $0.07; and male Yellow-headed Blackbirds $0.08, females $0.05. Annual loss was $5.4 ± 1.3 X 106 for all three species in aggregate, with Red-winged Blackbirds accounting for 52% of the loss. Blackbird damage represented 1.7% of the dollar value of the 1999 sunflower harvest in the northern Great Plains. This loss would be inconsequential if damage were distributed evenly; however, bird damage is often localized around wetlands and can be economically debilitating to individual producers. Although our model was based on regional population estimates, it should perform well at local scales, provided that a local population can be defined, accurately estimated, and remains stable in size over the six-week length of the damage period. Because of the large numbers of blackbirds that congregate in the region during August and September prior to migration, sunflower producers should expect some crop losses. The solution to the conflict appears to be one that focuses not on eliminating all damage, but on preventing it from exceeding 5% per field.

Citation Information
Brian D. Peer, H. Jeffrey Homan, George M. Linz and William J. Bleier. "IMPACT OF BLACKBIRD DAMAGE TO SUNFLOWER: BIOENERGETIC AND ECONOMIC MODELS" (2003)
Available at: http://works.bepress.com/george_m_linz/29/