When Bennie and Elaine Barcroft first traveled to western South Dakota’s Custer State Park for its annual buffalo roundup and auction 10 years ago, they were looking to buy more buffalo for their herd back in Tennessee.

But they got hooked and now are among dozens of cowboys and cowgirls who help corral nearly 1,300 rumbling bison each year across picturesque Black Hills prairie.

‘‘We started coming out for the sale and we fell in love with it,’’ said Bennie Barcroft, as he and his wife groomed one of their horses.