Vega Gull (Larus vegae) is the most common large white-headed gull at Choshi in winter. I saw several hundred and below are some images in various plumages with some personal comments. Although Vega Gull is considered a separate species by some, others consider it a subspecies of American Herring Gull or Herring Gull. I can see why.
Adult winter in alert posture. This individual has relatively light head-streaking. Orange/red orbital ring.
Near-adult (note black markings on bill). Note dark eye (quite common in Vega) and relatively pale legs (a good proportion of Vega have more 'raspberry pink' legs but certainly not all).
A very 'clean' headed bird, recalling
A more typical winter head pattern with thin streaking on the head and thicker, more blotchy streaking on the neck.
Black on wing-tip varies but most have black on p10-p5 with some including black markings on p4.
Another typical bird with black p10-p5
Black reaches p4 on this bird. Darkish eye.
2 cal yr bird showing dark secondary bar. Pale panel on inner primaries reaching outer secondaries.
2 cal yr. Beginning to gain some grey scapulars. Tail pattern typical.
A very striking and exceptionally 'hooded' bird. Note the fleshy pink legs.
Feeding Vega Gulls (with Black-tailed Gull bottom left). Note variation in wing-tip pattern. The flying bird has typically 'raspberry-pink' legs.