Mongolian Gull Larus cachinnans? mongolicus
March 25th 2005 Choshi Chiba Japan.
birds' were increasing, though many Vega Gulls still showed
complete winter plumage. Some of them might be summer plumage
Vega Gulls, and some others might be Mongolian Gulls. Identifications for adults in
late March are not easy.
A presumed Mongolian
Gull. The bill has a narrow black line that
ranges over both mandibles.
The gray on upperparts looked slightly
paler than most Vega Gulls (about Kodak 5.5?, similar to some
Thayer's Gulls in my impression) . And the leg color also
looked paler. The farthest bird in this image is a typical
same individual flying above the mixed flock.
The outer web of P4 has a black
marking, though it seems to be very small.
A presumed Vega
Gull Larus vegae turning into summer plumage
The face was not completely white. The black marking on P5 is
very narrow. No black marking on P4. The left bird is a
typical winter plumage Vega Gull.
Summer plumage Vega
I could not see
its wing pattern. Many birds on the day didn't move an inch
because of the strong wind.