This definitive/4th-basic Siberian Gull (Larus
heuglini) was photographed in Bahrain in early March
1999 by Martin Reid; the mantle shade and large white mirror on
P10 lead me to think it is a "Big Pale Heuglini";
note the rather limited fine winter speckling on the lower nape,
plus the very short tail that seems to be a feature of this form:
