South Dakota cowboys and cowgirls rounded up a herd of more than 1,500 bison Friday as part of an annual effort to maintain the health of the species, which has rebounded from near-extinction.
Visitors from across the world cheered from behind wire fencing as whooping horseback riders chased the thundering, wooly giants across hills and grasslands in Custer State Park. Bison and their calves stopped occassionally to graze on blond grass and roll on the ground, their sharp hooves stirring up dust clouds.
