Slaty-backed Gull Larus schistisagus
October 29th 2004 Sakawagawa-river Odawara Kanagawa Japan
A dark, smith-like individual. But the primaries look obviously brownish in the field.
A small, Thayer's-like juvenile.
Same individual as above. Note the thicker bill than the Black-tailed gull. Bill sizes of Thayer's Gulls tend to look similar to those of Black-tailed Gulls.
Adult winter. The P7 is the longest primary. Normal for this species.
An exceptional (?) late-molter that still has old P10 and 9.
4th? winter. The P8 is the longest.