This photo of American bison was taken in Yellowston. We found hordes of American bisons on our way from the Roosevelt to the Northeast Entrance. They were having dinner at that time. The expression of this male bison was so cute (note his tongue is out).
Recently I learned from TV that the lives of bisons in Yellowstone are very harsh during winter. In winter, Yellowstone is covered with thick snow. The only food sources are in the areas near the hot springs and geysers. However, the grasses and alge in this area are poisonous, so the bisons were slowly poisoned by the food they ate. In addition, the sulfur in the air near the hot spring also poisons the bisons. It was summer when I took this photo. They all look so carefree and leisurely. It's hard to imagine that they will had a hard time in winter.