The start of the annual Governor’s Buffalo Roundup at Custer State Park is just one phase of a year-round wildlife management strategy. The Park’s 1300-or-so bison have spent the past year roaming and grazing on 77,000 acres of mixed rangeland and woodlands. They’ve had calves, and now it’s time to bring them in for vaccinations and herd-thinning. About 350 bison will be sold at auction this year. Limiting the herd size is the best way to keep the buffalo from overgrazing the available forage. T