I have never seen this warbler on our property before yesterday. Their summer distribution is north of us, across Canada from coast-to-coast, and from Alaska down through the US Rocky Mountains. But I've only ever run into a couple. They look a lot like a fall Tennessee, but I see a lot of those and knew this was different. It took a bit of ID work to figure it out, however. One sure sign is that they sport yellow undertail coverts as opposed to the white of a Tennessee. It is said that their lack of identifying characteristics is, in fact, a clue to their identity. Also, the orange crown is seldom seen, even less frequently than the ruby-crowned kinglet.