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They used to roam the North American plains in the tens of millions, but now only about 20,000 remain in the wild, 3,700 of them in Yellowstone National Park. Officials are considering "selective culls" this winter to reduce the population to about 3,000. Half of the deaths will likely occur naturally, but the other half could be shot by Montana hunters (by opening up hunting grounds), captured for slaughter, or shipped elsewhere. The Associated Press obtained documents of the proposal, but officials say it is still a draft that could be subject to changes. Cattle ranchers have been pressuring the government to get rid of some of the bison because of competition for grazing space and worries over the spread of the animal disease brucellosis, which has been eradicated nationwide except in Yellowstone.