cgeoff

The first-year in the upper photo is Slaty-backed Gull. Note the bulky, short-winged structure and overall uniformity and darkness.

The two closest first-years in the middle and lower photos are neither of them the same bird. The highest bird is heuglini (no pale inner primaries, broad tail band (though not occupying all of tail), while the lower is mongolicus (obvious pale inner primaries, narrow tail band, overall paleness).

GeoffC