Slaty-backed Gulls Larus schistisagus
January 15th 2008 Choshi Chiba Japan
A very fresh individual. Note the brownish (not jet black), short primaries.
A bleached individual. An early-hatched bird?
One of the very typical examples of 1st winter Slaty-backed Gull. Note the moderately uniform overall coloration and short wings.
"Thedarkest" individual resembling American Herring Gull.
A rather tentative example showing some vegae-like features.This blackish narrow tail band and blackish primary tips resembled Vega Gull. But the rusty brown overall coloration and pale inner web of outer primaries in flight seemed to indicate Slaty-backed Gull.