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.
a quantidade de cervos, porque  não havia ninguém para caçá-los, só aumentou e aumentou  no Parque Yellowstone, e apesar dos esforços humanos  para controlá-los, eles conseguiram reduzir  bastante a vegetação lá até não sobrar quase nada,  eles pastaram tudo.