Bison (B. bison) sometimes erroneously called buffalo, are large, even-toed ungulates in the genus Bison within the subfamily Bovinae. Bison herds have dominance hierarchies that exist for both males and females. A bison's dominance is related to its birth date. Bison born earlier in the season are more likely to be larger and more dominant as adults. Males of the same size spar to determine which will be allowed to mate. Photo © copyright by Robert Faucher.