Crazy as a ...Robin

Just outside our downstairs bathroom window grows a bright green compact evergreen shrub of some sort. It doesn't actually grow much - in 15 years it has increased maybe a couple of inches in height. In another fifteen or twenty it may block one's view of the weathervane on the garage as one rests on the commode, reading, escaping, even contemplating the universe (ie, the weather implications of a west wind).

Lately, several times a day, I've been hearing a slight commotion in that general direction. Yesterday I just walked over and opened the door and thought I saw something fly away. Today, I was stealthier; having left the door open, I crept up quietly, slowly sneaking my head around the corner, and was rewarded with a view of a robin sitting on top of the shrub. He proceeded to attack the glass. Now the window is very small, about robin-sized if the robin is crazed and large, probably male, spreading its wings and puffing up its chest feathers. So maybe the glass was mirror-like and the robin saw a rival for his lady's affections (assuming that was his lady demurely plucking worms from the lawn below). I don't think he was after me. Was he?
Naturally, I thought this was unnatural (insane bird scratches glass, poops on sill, shatters solitude, frightens next house guest, causes constipation!) so I yelled and brandished my arms (from the safety of inside). He flew 20 feet to the big blue spruce and stared balefully at me. I did vigorous arm motions again. What little he could see through the tiny pane must have scared him. He left the premises.

Coward. We'll see if he dares come back to repeat his little macho display. I showed him what's what. Can't have nature attacking our sanctuaries.