Thayer's Gull (thayeri)

(last update: January 22, 2013)

Olympic Gull glaucescens x occidentalis adult, December 07 2012, Anacortes, WA. Picture: Jon.

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A common hybrid combo: Olympic Gull. This Glaucous-winged x Western is pretty common in Washington. HYBRID GLAUCOUS-WINGED GULL X WESTERN GULL (w. N America) can suggest Thayer’s Gull in plumage but tends to be darker above (mostly Kodak 6-8) and bill notably stouter often with a swollen gonys; also note large overall size, broad wings, and relatively short wing projection. Hybrids rarely show extensive, neatly demarcated white on P9-P10. Behavior is also a clue: If you think you see a Thayer’s Gull dominating feeding Western and Glaucous-winged gulls, then it’s most likely a hybrid.

Bird below obviously shows far too much pigmentation on P9 for Thayer's and note the greyish primaries instead of blackish.