Last month there was a bird who kept trying to get into my house in Naperville, Illinois. It would knock on the kitchen window with its beak for hours every day the whole month of May. I've never seen such a bird in Illinois before, and I'm pretty well-acquainted with birds in that territory (mourning doves, robins, sparrows, barn swallows, the occasional cardinal...). But upon further research, I found out that his name is "American Goldfinch" and he's as common as mud. He looks pretty, anyhow, and is probably stark raving mad. And though I saw him on a fairly regular basis, it is indisputably irregular to tirelessly knock at a human's kitchen window day after day. The bird is indefatigable.