Thursday, January 21, 2010

Putting in the time

One of my goals every year is to get to Tiscornia 100 times, a number I've never come close to reaching sadly. My spreadsheets suggest that I find a review bird there every 40 visits or so, though obviously during the fall months with a lot of bird turnover (and the concentrating effect of the lakeshore's angle) that number is more favorable. In winter the odds are considerably less favorable, but I try to make token visits to try to stay on pace (maybe a more concerted effort would net a king eider, Barrow's goldeneye, or ivory gull after a decade or so). The last few times I've been there, presumably the same female-type Black Scoter has been in with the Greater Scaup flock, the same female-type Lesser Scaup has been in with a few goldeneye, and the same 2 Horned Grebes have been in the channel.

Today the winds changed and pushed much of the ice farther out into the lake and more birds were present. The greater scaup flock had about doubled and the scoters had changed. I walked out the south pier hoping for good photo light, but by the time I got to the end the sun was lost for good behind the clouds.
There's a couple adult males with bright white sides, but most are first-winter male Greater Scaup, a plumage aspect that Sibley doesn't illustrate though that is attempted in the Nat'l Geo. These birds are undergoing what Pyle terms the pre-formative moult which runs from about September through March. This moult, present in some species of birds, replaces hastily grown juvenile feathers and frequently transitions birds into a more adult-like appearance. It only occurs in first fall/winter birds. Most of the birds have managed medium gray backs though still with some dark retained juvenile scapulars along the rear edge of the back. The white side panels are still blotched with darker juvenile feathers as well.

The male in the foreground here, though, is a bit behind with a mainly brown side panel and only a narrow line of gray scapulars starting to come through.
Did you notice the Lesser Scaup in the rear of this cluster?

Here's the Lesser cropped more tightly from the above photos
Note the coarser vermiculations of the back, the difference in crown peak placement, the thinner head, and more restricted black at the tip of the bill.

Finally poor shots of some of the other divers that have been around (I really could have used the sunlight).

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