This first-basic Thayer's Gull
Larus thayeri was photographed by Michael Donahue
at Seattle, Washington in late January 1998. Note that almost
all the mantle/scaps are paler-based first-basic feathers; the
upper tertials are heavily-notched and the wing-coverts are extremely
well-marked with white - does this represent some intergradation/introgression
with kumlieni?:
