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In the Prairie Pothole Region of North Dakota and South Dakota, blackbirds (Icteridae) gather by the thousands in large premigratory roosts in late summer and early fall. Wetlands dominated by cattails (Typha spp.) provide ideal roosting habitat for these aggregations. Sunflower fields near large roosts can receive substantial damage. To eliminate potential roosting sites, Wildlife Services of the U.S. Department of Agriculture has implemented a cattail management program that aerially sprays dense cattail stands with the herbicide glyphosate m-(phosphonomethyl) glycine]. The continued viability of the program depends on a positive benefit-cost ratio and minimal environmental impacts. In this paper, we discuss the economics and ecological implications of cattail management in the northern Great Plains.