Tap.
Maybe the window? “Once upon a midnight dreary, while I pondered, weak and weary--over many a quaint and curious volume of forgotten lore— while I nodded, nearly napping, suddenly there came a tapping, as of someone gently rapping, rapping at my chamber door…” There’s that noise again. From their hoarse cries to their beady little eyes, they were creepy enough to inspire Edgar Allan Poe’s masterwork..