36 American Herring Gull / Amerikaanse Zilvermeeuw Larus smithsonianus, first-winter, Boston, Massachusetts, USA, February 1999 (Pat Lonergan). Very distinctive individual with bicoloured bill, contrastingly pale head, dark lower hindneck continuous with uniformly dark underparts and many retained juvenile scapulars. Note dark base to greater coverts and dense patterning on vent and undertail-coverts. 37 American Herring Gull / Amerikaanse Zilvermeeuw Larus smithsonianus, first-winter, Boston, Massachusetts, USA, January 2001 (Pat Lonergan). Note pronounced greater-covert bar, and that, unusually for second calendar-year smithsonianus, bill has acquired very little pale at base.
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