Slaty-backed Gull (schistisagus) / オオセグロカモメ / 큰재갈매기

(last update: December 2015)

Kim Seog-min (South Korea)
Hideo Shimura (Japan)
Peter Adriaens (Belgium)
Mars Muusse (Netherlands)

Slaty-backed Gull (schistisagus) adult, March 10 2012, Choshi, Japan. Picture: Peter Adriaens.

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In dull weather conditions. Variation in upperpart tone of adult Slaty-backed Gull. Left adult with less streaking on head, has discernibly paler upperparts than right one. Body shape is pretty much identical though. No real suggestion of Glaucous-winged Gull influences, as wingtips appear still deep black in the left bird (not paler than normal bird right). Pattern of outer primaries looks normal for Slaty-backed Gull. Note also pattern of inner primaries with white indentations.