"D" is a 2nd-cycle Herring (or at least mostly Herring).1st-cycle
would have coarser barred/checkered covertsrather than smooth-looking
finely marked, and would nothave a pale iris or white head quite yet.
The Glaucous-like bill is typical of this age and is not uncommon even
in 1st-cycle Herring, so by itself doesn't necessarily
The gull in flight looks like an Olympic.