Date: 2/6/18 9:13 am
From: Lars Per Norgren <larspernorgren...>
Subject: [obol] Lesser Black-backed Gull , East Delta Park, Portland
About 4:30pm Monday 2/5 I saw a 2nd year Lesser Black-backed Gull on the northernmost baseball field at East Delta Park. There were 3000 minima Cackling Geese on the ball field when I arrived with 9 gulls mixed in. The geese moved a hundred meters north to a sunny patch of grass and the gulls proved to be 7 adult Glaucous-winged and a 1st year Thayer's. I didn't ID the LBB until I got home. I always have a binocular in the car and almost never a field guide.
It appeared slightly smaller than the 1st year Thayer's, more attenuated than other gulls I have seen this winter (I haven't been seeing any Mews) with nearly black folded primaries devoid of apical spots. This made me think sub-adult Herring Gull but the bill was dark except for the base of the lower mandible, and a Herring Gull at this age should have a mostly pale bill--the mantle was mostly gray, esp. all the scapulars. The legs were flesh colored--neither yellow nor pink, rather a dirty peach. The peculiar thing to me was prominent black patches on the tertials, like the black on a Western Gull's tail when it's almost in full adult plumage--truly black, bleeding into seemingly pure white. The back of the neck had fine gray streaking.
Had I realized the rarity of the bird I would have walked closer to it, presumably seen some facial detail. The black on the tertials didn't fit any of the usual suspects, nor any of the other marks frankly. When I got home the picture of a second winter Lesser Black-backed Gull in Sibley was an excellent fit except for the black in the tertials. Lars
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