Quote:
Original posted by cgeoff at 1/02/2015 21:30 
The narrow tail band and fairly clear-cut, obviously pale inner primaries and pale bill base identify this bird as Yellow-legged Gull.
GeoffC
Well, Yellow-legged Gull - Larus michahellis - occurs only in Europa. Together with Caspian Gull - Larus cachinnans is was once one species, but they have been split.
Furthermore the bird in the picture, a Mongolian Gull, has been lumped under Vega Gull - Larus vegae.
So it's a Vega Gull - Larus vegae, or more broadly a Mongolian Gull - Larus vegae mongolicus.
See
http://www.worldbirdnames.org/bow/coursers/ to get it 'always right', until they split and/or lump again... The HKBWS does not follow this and so would call this gull a Caspian Gull - Larus cachinnans.
