via backpacker blog

Each winter the bison that leave Yellowstone in search of food are rounded up and shipped to slaughter. The reason? To keep the parks bison from passing disease on to cattle in near by ranch lands. Nine environmental groups in all have joined together to sue the National Parks Service and the Forest Service. The environmental and American Indian coalition group have lobbied their case to government agencies and congress, but with no success. If won, the lawsuit would bar these agencies from participating in the round up and slaughter.