野牛是美国独特风景的一部分。波德内先生则认为野牛的数量应该被限制，“从科学来讲，蒙大那地区不是真的需要野牛。野牛是一个有5000年历史的物种，它们和美国北部的草原和牧场一起进化。
事实上，黄石野牛大约有一半遭受了布鲁氏菌病——一种欧洲牛群带到美国的细菌疾病——可能引起牛流产。
In fact, about half of Yellowstone's bison have been exposed to brucellosis, a bacterial disease that came to North America with European cattle that may cause cattle to miscarry.
如今，有100多头野牛闲适的生活在蒙大拿州东部3万英亩的美国草原自然保护区，这是一个世纪以来它们首次在此区域定居。
More than 100 bison now roam the 30, 000-acre American Prairie Reserve in eastern Montana—the first time they've inhabited that region in a century.
他们的手段如此“有效”，据估计美国的野牛数量从1800年的约6000万头急剧下降到1890年的750头。
The slaughter was so "effective" that the population of bison in the U.S. is estimated to have dropped from around 60 million in 1800 to as few as 750 in 1890.
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