1st winter/summer

Slaty-backed Gulls
Larus schistisagus
March 15th 2005 Choshi Chiba Japn

Same individual as the left bird in the above 2 photos

In the individual in front, replaced feathers seem to be restricted to the upper scapulars/mantle.

Same individual as the front bird in the above photo.

Note the typical brownish primaries.

Same individual as above

3 Slaty-backed Gulls

4 Slaty-backed Gulls
Note their variable brownish (not blackish) primaries .

One Glaucous-winged Gull among Slaty-backed Gulls.
Glaucous-winged Gulls tend to look obviously grayish and uniform than Slaty-backed Gulls

2 Slaty-backed Gulls, and 1 Glaucous-winged Gull (right).