Howard, I have seen young Sandwich Terns like the one you describe. The bill of juveniles is typically smaller than the adults'. This is mentioned in most texts. The color of the bill is a different matter. Apparently some juveniles retain the yellowish-colored bill from the downy stage which I can find described only in Bent. I remember discussing this bill color with Claudia Wilds some years ago. She had also seen such birds. May be we can find out the rest of the story when the tern book comes out. Bob Ringler