Adult Western Caspian Gull (Larus cachinnans
ponticus) (left) and barabensis
(right), photographed by Martin Reid in Bahrain, early March 1999.
Note the difference between the gray of the upperparts, and especially
compare the primary patterns: this ponticus is closer to
the dark extreme for this form, while the barabensis is
fairly typical for a double-mirrored bird :