Nice photos, Cherry. I think their identities are as follows:
Pic 1. 1st winter Vega Gull. The most obvious features identifying this bird is the relatively pale and unmoulted median and greater coverts, and the pattern of the scapulars.
Pic 2. 2nd winter Yellow-legged Gull (mongolicus). Rather pale upperparts, extensive grey in the median coverts for this age, relatively unmarked white underparts.
Pics 3 & 4: 2nd winter Black-tailed Gulls. Relatively dark grey upperparts, extensive brownish wash on rear of head, clean-cut two-tone bill, dull yellowish legs.
Pic 5. 2nd win Yellow-legged Gull. Same as above, but based on the bill pattern, a different bird.
Nice photos. How many birds at this site? Is it along a river, or along the coast.
Geoff
