Oklahoma resident Les Vandever said he is still stunned after seeing a man charging into a herd of bison in Yellowstone. "It was a moment of unbelievable stupidity," he said. “We were sitting in our car, just dumbfounded." Man charging into herd of Yellowstone bison (Photo by: Les Vandever) It’s the summer season in Yellowstone National Park, which means it’s open season for brazen bunglers to try their luck with bison. Les Vandever of Sand Springs, Oklahoma, was in Yellowstone last month when he stopped near Floating Island Lake in northern Yellowstone to see if he could spot any bears....