I can report that the only birds that don't totally ignore my new bird call are the bushtits. It drives them nutty, and since they start out a little nutty, it's comical to watch. They run in packs, and they chatter at each other constantly, so they must have thought I was one of them. After they listened for a few minutes and looked around quizzically, one tiny bushtit flew out of the tree and directly at the screen door I was standing behind. It swerved off at the last second, but as often as I've watched these funny little birds, I've never had one get that close to me before.
I don't think you can call bushtits, because they seem to do pretty much whatever they want. But when they're around you can mess with them.