A robin flying into the kitchen door yesterday afternoon, repeated the same hopeless effort every few seconds, despite all efforts to deter him. He continued this for 4 straight hours until dark. And now at dawn he has resumed his quest with even greater persistence. Meaning?

a bird-wise friend says: Various birds that nest not far from humans see their reflection in a window and perceive it as a rival (this applies to the males, of course!). So they fly at the window to attack. We had a tufted titmouse one year that attacked every mirror on a vehicle