The U.S. Fish and Wildlife Service (FWS) manages almost 1,400 bison spread out amongst seven herds located in Iowa, Colorado, Oklahoma, Montana, Nebraska and North Dakota. About 70 of these bison live at the Neal Smith Wildlife Refuge in Prairie City.
FWS aims to preserve the species genetic diversity with as little human intervention as possible by allowing the forces of natural selection determine which bison live and die. However, because herds are isolated from each other the agency conducts genetic testing to prevent inbreeding.