This American Robin attacks the window in the sliding doors out from our bedroom. Presumably he thinks he sees a rival in his reflection in the window. We tried hawk silhouettes but it didn’t work. I’ll try again with a larger, coloured image, but I might leave it a couple of days until I get a brighter day so I can take less grainy pictures. The pictures would also look better if he wouldn’t leave such a mess on the windows.
Sometimes he takes a break on the table on the deck.
Otherwise he can spend hours “fighting” his reflection. He carried on for weeks last year.