Taxonomy is complex and unsettled. AOU and Clements/eBird retain a traditional arrangement of one species of Herring Gull. H&M4 and HBW split North American populations as a separate species, American or Arctic Herring Gull (L. smithsonianus). IOC further splits Vega/Siberian Gull (L. vegae) including Mongolian Gull citing Collinson et al. 2008, Ysou (Dutch Birding 24:271-298, 2002). Brazil (2009) further splits Mongolian Gull from Vega.
Regardless of taxonomy, this is an adult American Herring Gull in non-breeding plumage showing gray head streaking. It is a rarity in Japan and we were fortunate to see it and document it with photos. Note its long bill and pale eye with orange-yellow orbital ring. Its mantle color averages noticeably paler than other races, especially the local and abundant L. a. vegae which has an orange-red orbital ring. Eye color varies in vegae but usually dark, always pale in smithsonianus. Canon PowerShot SX60.
