While engrossed in trying to get reasonable images of the Slaty-backed Gull, many other gulls of interest came into view. One of these, an adult, I almost glossed over as an American Herring Gull. It had black primaries, gray upperparts similar in tone to smithsonianus or maybe slightly darker, and didn't look especially small compared to the surrounding 'smiths'. I'd already seen a number of adult Kumlien's Gulls with dark eyes and gray-to-dark gray primaries, so wasn't particularly alarmed when I saw this bird but started taking images of it as a bird of interest. Unfortunately, I never achieved a good shot of the spread wing, but found several images that revealed an obvious black leading edge to P10, and a clear black subterminal mark across the outer of an otherwise white wing tip. Also, the head and bill jizz didn't strike me as being particularly Kumlien's-like.
Slaty-backed Gull with raised wings towards the rear left of the image. This shot also contains at least one first-cycle Kumlien's Gull (lower left) but can you see the adult Kumlien's/Thayer's?
Cropped detail from the same shot. The bird of interest is just right of center. It shows a dark eye, 'herring gull-like' or darker gray upperparts, and clearly black primaries. The primaries look matt-black rather than the jet-black of the surrounding adult smiths.
Image capture showing blackish leading edge to P10, and a clear black subterminal mark across the outer of an otherwise white wing tip. Other images (eg.below) show black outer edge to P10.
On the whole, another most interesting gull from Niles Pond.
NB. I'd be really interested to know if anyone's discovered a method of reading the wing tip patterns of Thayer's/Kumlien's on the closed wing?
JPS.
Slaty-backed Gull with raised wings towards the rear left of the image. This shot also contains at least one first-cycle Kumlien's Gull (lower left) but can you see the adult Kumlien's/Thayer's?
Cropped detail from the same shot. The bird of interest is just right of center. It shows a dark eye, 'herring gull-like' or darker gray upperparts, and clearly black primaries. The primaries look matt-black rather than the jet-black of the surrounding adult smiths.
Image capture showing blackish leading edge to P10, and a clear black subterminal mark across the outer of an otherwise white wing tip. Other images (eg.below) show black outer edge to P10.
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