It was time to play with my new toy :) By the way, longer your lens is, safer you are ! Among other very advanced amateurs, I looked rather like a newcomer. The real wildlife enthusiast has a 600 mm with a range extender, mounted on an heavy tripod standing on the plateform of his truck.
I stayed at the campground close to the southern entrance. Early in the morning, I took my car to drive north in order to see some samples of the wildlife. On the way, I took some pictures at West Thumb and on the bank of Yellowstone Lake and Yellowstone River.