Earlier this week I saw a hummingbird approaching some flowers in front of my office building.  As I approached, it zoomed off across Wisconsin Avenue (in Bethesda).  When I entered it in my list of birds seen from and near my office, I discovered that Chimney Swift was missing!  That brings me up to 74 species seen from my office window, around my office building, and out to the parking lots I use.  
Rob HiltonSilver Spring