Robins mate now. Male birds are particularly aggressive at this time. They will fly at each other, bouncing off each other’s breasts—a mating ritual that is not hurtful but mainly for show. The true courtship is conducted by song, the female lured by the more attractive singer.
If a male catches his reflection in a window, he will think it a rival and spend days flying into the pane leaving behind feathers and blood. Closing blinds to minimize reflective properties of windows helps as does posting silhouettes of predatory birds such as hawks.
A robin has been beating on my window for several days now. I’ve taken all measures which usually work; however, this lad has decided to take on the “enemy hawk.” So while he’s busy bonking the window, no doubt his rival exercising trills has won the bird. Call it natural selection, culling of the herd.
Still, I feel for the feathered fool.