I just contemplated dumping some leftover seeds from a trail mix I was eating outside my window and into the gutter. There's a fairly large tree next to my apartment and birds do like to hang around it. A gutter seems like the perfect shape for a bird feeder. And I'd hate to waste these seeds.
Disregarding the fact that there's a screen in front of my window, I think attracting squirrels would be a major concern if I poured seeds out my window.