Since a particular robin is still trying to smash his way into our house through a window (see blog below), I decided to do a ltitle research. It turns out that robins (and cardinals) are very territorial and when they see their reflection in a window, they try to engage with the "other" bird to get him out of the way.
Since the window pecking began a couple of weeks ago, we had been trying to stop the bird from crashing at the window by placing stuffed cats in his line of sight, placing some garden statuary in his path (a bunny and St. Francis) and propping a folded up lawn chair in his way.
No luck. Yesterday he started pecking at a different window in the dining room. He would perch on the rhodedendron outside the window and then make a kamikaze move directly into the glass. I shook the blinds at him a couple of times but to no avail.
I'm not sure how long this will go on. You would think the bird would have figured out his task is useless by this point, but I am not sure that is going to happen. Being a bit on the stubborn side myself, I realize this could go on till the birds fly south in the fall. Hoping the windows hold up!