The numbers of deer, because there was nothing to hunt them, had built up and built up in the Yellowstone Park, and despite efforts by humans to control them, they'd managed to reduce much of the vegetation there to almost nothing, they'd just grazed it away.
O número de veados,  por não terem ninguém a caçá-los tinha subido e subido  no Parque de Yellowstone, e mesmo com os esforços dos humanos  para os controlar, eles conseguiram reduzir  muita da vegetação por lá a quase nada,  simplesmente pastaram-na toda.