He's pretty small, about 3.5", and has a short warble for a song. He doesn't quite sing the "Cheeseburger" song of the Carolina wren, but yet, I am thinking he's a Carolina wren. His bill isn't right for a brown creeper, either (would have been my next guess). Any opinions on this?
Also, here's one of the Nuthatch Nation (tm). They are here all day, every day now, apparently. Whatever that is about.