American bison were reduced from 30 million to near extinction before conservation efforts rebuilt populations, but welfare challenges remain in managed herds.
Bison in commercial herds are managed more like livestock than wildlife, with welfare standards varying considerably between operations. Overcrowded commercial herds prevent the extensive grazing and movement that characterize wild bison behavior. Yellowstone bison that migrate out of park boundaries face hazing and culling based on brucellosis transmission risk - a welfare harm that is contested scientifically and ethically. The brucellosis-cattle conflict has maintained artificial population caps on the most truly wild bison population in the USA. Conservation programs that prioritize wild behavior over agricultural management provide better welfare outcomes.