Been to YNP several times. I'm still amazed at the number of people that think they're in a petting zoo. I saw the result of a young lady that decided she could drive through a herd of Bison crossing the road. She was reading the riot act to a Ranger about her driver side door which was severely dented. Bison are big animals with pea sized brains and no nerves in their skulls. And Momma Bison had her baby with her.
They used to put the table scraps from the restaurants in a pile along the road for the bears, but people got too close so they could take a picture. Personally, I feel sorry for the Rangers. They have to perform their duties without laughing.