Slaty-backed Gull (schistisagus) / オオセグロカモメ / 큰재갈매기
(last update: December 2015)
Slaty-backed Gull (schistisagus) 1st cycle, January 31 2010, Choshi, Japan. Picture: Gullog.
See Gullog's Blog.
Maybe pure Slaty-backed Gull, but several odd features: very delicate bill, rounded friendly head, boldly patterned coverts and elegant appearance. If not a hybrid with Vega Gull, this is a bird in the smaller end of the spectrum (females?).
About half of the scapulars replaced. Tail almost completely dark. Much white in GC.