Revered as America’s national mammal, bison have made a spectacular recovery after near extinction in the late 19th century. But the wild herds of bison roaming Yellowstone National Park have outgrown the space available for them in the Park, and authorities are harassing and slaughtering bison that migrate across Park boundaries to reach grasslands they need to survive. Gary Strieker talks with Mike Mease, co-founder and coordinator of the Buffalo Field Campaign, to review the reasons why bison are considered a threat to cattle ranches around the Park and what the Campaign is doing to ensure the last wild herds of bison can live free and thrive.