Age: The medley of old and new mottled upperparts, along with retained, pointed, outer primaries give the impression of 1st summer gulls. Indeed all three of our July Quiz birds are roughly 1 year of age (now in their 2nd prebasic molts).
Identification: We'll begin with the darkest individual on the far left. The lightly barred undertail coverts and significantly solid dark upperparts suggest a black-backed gull. The defined striations along the nape and neck are found in Lesser Black-backed Gull, and the size and structure agree with that species.
Next, the lighter individual on the far right shows a mixture of pale grays to the new scapulars. These feathers are light enough to steer us away from a dark-backed gull. The heavily marked undertail coverts and body structure fit Herring Gull, and there is little doubt it is any other large pale gull.
The trickiest of our group is the center bird in the back. At first glance one may pass it off as another young messy summer Herring Gull. However, the delicate bill and small rounded head give it a more graceful expression. There are hints of a pale uppertail and pale underside to the left wing (compare this to the darker underside of the Herring Gull's right wing). The smaller and more compact size is also noteworthy. The center gull was identified as a 1st summer Thayer's Iceland Gull. An open wing to seal the deal:
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| The underside to the primaries are genuinely pale and not strictly due to fading and bleaching. |
Our July 2018 Quiz was taken in Sheboygan County, Wisconsin on Lake Michigan. 23 June 2018.
