On Sep 20, 2015, at 2:28 PM, Derek Lovitch <freeportwildbird@yahoo.com> wrote:
Hi all,
I completely forgot that articola delays molt as well.
It's interesting that the breeding biology and molt of these two populations of Dunlins, separated by just 10° latitude, is rather different. I mixed this up. The western birds take longer to molt, but it is on the breeding grounds.
One of the key differences between those western North American Dunlins and "ours" is the absence of fine streaks on the flanks and undertail. Our birds, hudsonia, have them. This is true in winter plumage birds too. So far as I can tell, the Alaskan birds are essentially white down the flank, streaks extend only to the forward edge of the belly patch, or in winter, are not present on the undertail coverts (see Browning 1977). It appears to that arctica (Greenland) and probably the Euro birds are mostly white down the flanks too. Two useful references:
Browning, M. Ralph. 1977. Geographic variation in Dunlins, Calidris alpina, of North America. Canadian Field-Naturalist 91(4): 391-393.
Greenwood, Julian G. 1986. Geographical variation and taxonomy of the Dunlin Calidris alpina (L.). Bulletin of the British Ornithologists Club 106 (2): 43-56.
Let's just wait and see what Noah and Derek come up with for photos. The longish bill does not sound promising for a Greenland/Euro Dunlin. There are a few summering Dunlin on both coasts that can show breeding plumage into late summer and fall. I was sent a photograph of such a bird from Tampa, Florida, from late August. That bird did not have the fully red back one might expect and may have been a 1-yr-old. The photos were quite good and showed a long bill like hudsonia and, importantly, fine streaks all the way back to the rear flanks, eliminating other possibilities. I think the deep red in the bird's back and scapulars only would have shown at close range. It's late enough in the season that Noah and Derek's report is highly intriguing though.
Louis Bevier
Fairfield
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