1st winter
Slaty-backed Gulls 
Larus schistisagus 
Mar 12th 2012 Choshi Chiba Japan


Slaty-backed Gulls generally have broad tail band, and often show a all-dark tail like Western Gull. But actually many birds have variable amounts of white on their outer tail feathers. Their overall coloration looks less contrasty than Vega Gull, but on the other hand usually gives a patchy, uneven impression compared to Thayer's and Glaucous-winged Gulls. 







This individual shows relatively strong contrast between dark wingtips/tail-band and other parts, so overall pattern in flight resembles Vega Gull. But its overall impression in the field was Slaty-backed Gull.

Photographed as a variation of Slaty-backd Gull. But looks rather hard to distinguish from Vega Gull in this photo.