Ah, youth!

This bird was photographed in College Park, Maryland, on June 24. You will be stunned to learn that I figured out what it is. Too bad the book I've got doesn't show juvenile plumage - but the Internet does, if you can begin to guess. Since this was robin-sized, roughly, and acting like a robin, I looked up juvenile robin - and bingo! What a remarkable difference between this guy and his parents... You can certainly tell they're thrushes, though, with the eye-stripe and speckled breast.