Semenov U.A. of WWF-Russia, 2014, "The Wisents of Karachay-Cherkessia", Proceedings of the Sochi National Park (8), pp.23-24, , KMK Scientific Press The heads and forequarters of American species are massive, and both sexes have short, curved horns that can grow up to 2 feet long, which they use in fighting for status within the herd and for defense.