Francois, you reminded me of that time I came home from a huge Warehouse Rave at about 6AM, and was all ready to go to sleep, in fact was just barely managing to keep my eyes open, plus I had a splitting headache from the 10000 watt sound system of the previous night, and then these three sparrow came and sat on my window and began blaring out birdsong. I almost screamed. So then I snuck up behind them and attempted to slam my fist against the window. Unfortunately, my fist was stronger than the window and I have the scars to show for it today.
Moral of the story: Don't bang on windows when you have a hangover.