Sorry for the late post - I temporarily cannot post from work. However, with the cold weather and formation of ice on Schoolhouse Pond, the last few weeks have had larger gull numbers. Today at lunchtime I sorted through the flock and the highlight was a 1st cycle Thayer's Gull. It was a pretty, "frosted" and well-marked bird, and a nice surprise given that there have been almost exclusively Ring-billed Gulls (and a few Herring Gulls) this winter. I saw the bird on the ice as it rested, preened, and slept. The bird was much lighter overall than the surrounding Herring Gulls. Perhaps what stood out the most (in addition overall lighter appearance and the paler brownish, whitish-edged folded primaries), was the pattern of the back, mantle and scapulars. I studied these feathers through my scope, and got comparisons with nearby 1st cycle Herring Gulls. The mantle and scaps of the THGU displayed the distinctive "anchor" pattern, with a dark tan subterminal line, dark shaft and otherwise pale grayish feathers (including the slightly frosted tips). My full description from eBird is copied below:
1st cycle gull. Separated from 1st year Herring Gull by a combination of several marks, especially the frosted overall appearance, brownish, pale-tipped folded primaries, and well defined, anchor-shaped scapular feathers (visible via scope at 40+ magnification). Field notes included the following: white ground color to the head, with brown streaking, dark eye, black bill. Mantle and scapulars had anchor shaped markings, with a darker tan fringe around the tip and dark shaft. The rest of the individual scapular feather appeared off-white, setting off the contrast with the darker "anchor" shaped areas. Coverts were also pale, with frosted edges. Primaries were brownish black, edged in white. Tertials were medium brown, intermediate in color between the mantle/scapulars and folded primaries. Undertail coverts were white with brown bars. The gull was the size of a small Herring Gull. Seen at rest only as the bird sat on the ice, rested, and preened.
As I mentioned earlier, the gulls have been present in decent numbers at Schoolhouse Pond the last two weeks, but diversity has been extremely limited. I've had several days with 700 or 800 gulls, but Ring-billed being the only species present. Other days, I've had roughly 500 - 800 Ring-billed Gulls and a few dozen Herring Gulls, but nothing else. The only exception last week was a flyover 3rd cycle Lesser Black-backed Gull. Last winter was pretty slow gull-wise at the pond as well, and the Thayer's today was my first white-winged gull in approximately 2 years at Schoolhouse Pond. Good birding,
Fred Shaffer
<GlaucousGull...>
Crofton, Anne Arundel
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