I seem to have one chickadee who acts very strangely. It lands on my tube feeder which is about 8' from my office window on a covered porch. Grabs a seed or two then flies either directly into the window or to a thermometer gauge I have mounted just outside the window and looks inside. Sometimes it jumps/flies straight up from the thermometer. I am guessing it somehow is responding to its own reflection, although that does not seem to be a recurring problem with other birds or other chickadees (assuming it is the same bird, but who knows). The thermometer is becoming covered in bird doo, and I'm fearful this little bird is going to knock itself silly. I checked to see if perhaps it was trying to build a nest above the window, but nothing there. This morning I cut out a picture of a larger bird and taped that to the window hoping that will discourage my little kamikaze. Any thoughts?
I have seen other birds do that but no chickadees, he is defending his territory by attacking his opponent, which of course is his own reflection. 
Maybe put a hawk image in your window, that may work.
