South Dakota cowboys and cowgirls rounded up a herd of more than 1,500 bison on Friday 29 September as part of an annual effort to maintain the health of the species, which has rebounded from near-extinction.<br /><br />Visitors from across the world cheered from behind wire fencing as whooping horseback riders chased the thundering, woolly giants across hills and grasslands in Custer State Park.<br /><br />Bison and their calves stopped occasionally to graze on blond grass and roll on the ground, their sharp hooves stirring up dust clouds.<br /><br />Each year Custer State Park holds one of the nation’s few bison roundups to check the health of the bovines and vaccinate calves.
