Living near Yellowstone and Grand Tetons National Parks, we are often visitors to one or both. Many times we run into "animal jams" -- clots of tourists parked along the road to view (from a distance) elk, bison, bears, and so on. Rangers are often dispatched to control traffic and to stop tourists from risking their lives by approaching the animals too closely.

Last Fall my brother was visiting and we decided to stop, whip out the binoculars and camera, and stare and point at a field empty of animals. We wanted to see how many other people would also stop. If asked by a ranger we were going to answer, "That's the finest specimen of Populus tremuloides we've ever seen!" (If you don't want to look it up, that's the Latin name for an aspen tree.) If asked by tourists we were going to say, "It just moved behind those bushes!"