Summering Scaup Flock at Albany Bulb


Alexander Henry
 

Hi East Bay birders!

I just wanted to discuss the summering scaup flock at Albany Bulb. It seems historically that this area has hosted wintering Greater Scaups, and as Ethan Monk points out, Lesser Scaup are very rare in summer nearby portions of Contra Costa.

However, this summer, all conclusively identifiable photos of scaup taken at Albany Bulb have been Lesser Scaup.

Not to single out Dean LaTray, but I will use his photos as an example, simply because he has gotten the best quality, most clearly identifiable photos of these birds.

https://macaulaylibrary.org/asset/244400421

Here is one of Dean's photos. This is a straightforward male Lesser Scaup - which proves that there are summering Lesser Scaup in the area.

https://macaulaylibrary.org/asset/244606681

Here is another excellent photo - labelled as Greater Scaup - only, this bird is also, actually, a Lesser Scaup. I understand the confusion here, as the bird's head looks broad and rounded, however this is largely an artifact of posture. The spread wing pattern is distinctive - the white bar ends abruptly at the inner primaries, and the grayish outer primaries contrast the blackish primary coverts. This is diagnostic for Lesser Scaup. In a Greater Scaup, the white bar extends well into the primaries, but the outer webs of the outer primaries are black, not gray, so the outer primaries do not contrast as much with the primary coverts.
Also, the second male in the background in this photo is also a Lesser Scaup.

Anyway, my points are that 1) there are at least a few wintering Lesser Scaup at Albany Bulb and 2) there seems to be a tendency to misID Lessers as Greaters.

Have there been any Greater Scaups at Albany Bulb this summer? Perhaps a few have passed through, as there has been some turnover of individuals in the flock, but I stand by my assertion that the scaup flock at Albany Bulb this summer has been majority Lesser. It would help clarify the status if anyone could get a conclusively identifiable photo of a Greater Scaup at the Bulb in the next couple weeks though.

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