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We study bison (Bos bison) herds that are managed year-long without protein or energy supplements in large mixed prairie pastures in Nebraska, South Dakota, and North Dakota. We also manage cattle (B. taurus) grazing during the growing season in separate, but adjacent pastures. Management reflects the divergent evolution of bison and cattle with their respective human cultures and landscapes. Bison exhibit a stronger preference for the perennial grasses that form the prairie matrix, and they are strongly attracted to open landscapes during the growing season. Cattle include more forbs in their diet, and they use wooded areas and riparian zones more intensively. At similar annual stocking rates, the amount of grass remaining at the start of the dormant season is higher under year-long bison grazing compared to growing season cattle grazing. There are inherent differences between bison and cattle, suggesting that they be managed differently. Under our respective management regimes, bison are less productive than cattle, but they require less processed feed and labor inputs. We recommend that the focus of mixed prairie conservation be on developing ecologically sound goals and practices for grazing management, rather than on whether bison or cattle are more appropriate grazers.