American bison were reduced from 60 million to fewer than 1,000 individuals by the late 19th century. Ongoing restoration raises complex welfare questions about herd management, culling, and the balance between wild behavior and managed landscapes.
Bison welfare in restored populations involves the tension between providing space for natural behavior and the realities of managed landscapes. Fenced reserves inevitably restrict the migration that bison evolved to undertake, compressing populations onto finite grasslands that can become overgrazed. Culling programs to maintain population balance within reserve capacity are controversial but unavoidable without predator reintroduction. Brucellosis management at Yellowstone involves bison being hazed, captured, and sometimes slaughtered when they cross park boundaries — causing significant stress to individual animals. Male bison fighting during rut causes injuries that can be fatal. These welfare harms exist within the context of a remarkable conservation success — bison today are vastly better off than the species was in 1900 — but ongoing management decisions continue to create welfare trade-offs.