Slaty-backed Gull  Larus schistisagus
October 29th 2004 Sakawagawa-river Odawara Kanagawa Japan

1st winter.

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1st winter.

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A dark, smith-like individual. But the primaries look obviously  brownish in the field.

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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.

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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.