This Siberian Gull (Larus heuglini)
(with a barabensis behind) was photographed at Sohar, northern
Oman (c. 25N, 56E) in early March 2000 by Arend Wassink; note
how it looks very like the "normal" heuglini
I photographed in Bahrain, fitting Dave Sargeant's earlier comment
that most birds in northern Oman look like "classic"