Some birds chirp all night this time of year. It has something to do with them sitting on eggs. My mom explained it last year. She knew exactly which birds do it, but I don't remember at this point what kind she said. Makes it very difficult to sleep with the windows open, though, and this is about the only time of year the weather is nice enough to do so. It's actually pretty quiet tonight here in TN, but I can't sleep for some reason.