This particular bluebird box is a hot property this year. Earlier in the spring, I watched two bluebird couples fighting over it, but I never saw what looked like nest-building. This guy let me know that this box belongs to him. I generally keep pretty far back so as not to disturb any activity. Apparently, pretty far back was not far back enough. I took a few pictures, then gave him his space. When I went back to this spot a couple of weeks later, it looked unoccupied again. Perhaps it is a haunted nest box. Click on pictures to enlarge.