Yellow-billed Loon (흰부리아비, 여름깃)
Gavia adamsii

Image Source:
Byoung-Oh Won, "A Field Guide to the Birds of Korea", Kyohaksa, 1993

"KoreanBird-Yellow-billed_Loon_J01-incubating_on_nest-summer_plumage.jpg"

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The yellow-billed loon or white-billed diver (Gavia adamsii) is the largest member of the loon or diver family. The main distinguishing feature from other loon species is the longer straw-yellow bill which, because the culmen is straight, appears slightly uptilted. It breeds in the Arctic and winters mainly at sea along the coasts of the northern Pacific Ocean and northwestern Norway.