We don't have a bird feeder, or birdboxes. but recently there have been several species of birds coming to nest in our window sills (we have a wall of a bunch of windows, and now there at 3 birds nests in them) also, birds will continuously throw themselves up against the glass. i woudn't be so freaked, but the birds are all diffrent kinds. as i write this now i am listening to two diffrent birds throw themselves against a window. I don't mind this...it just strikes me as odd. and it has never happened before in all of the years i've lived here. anyone have any answers?