That Dunbeg Gull again – thumbs up for Thayers?

Jim Dickson from Argyll has asked me to spread the word on feedback he has had from Steve Hampton in the USA re the Argyll ‘Thayers’ Gull. Steve is a leading light on the ID of this taxa, so certainly worth taking a few moments to read this through:

Jim,

It’s nice to have such great photos! This looks like a typical Thayer’s Gull. We have several hundred present here now and this bird would fit right in. I can’t imagine anyone on the West Coast, and probably not even the East Coast, of the US, would consider calling this a Kumlien’s. It would certainly not be accepted as one in California; it would be called “a fairly typical Thayer’s”.
I assume you’ve seen the birds at http://www.tertial.us/gulls/kuml1.htm (which I keep adding to).

Using my scale and going point by point:

PRIMARIES – 4; very typical; the size of the pale edge is variable and there is nothing remarkable here for Thayer’s
SECONDARIES – 4; seems to be a strongly contrasting dark bar (at most lighting angles); very typical of Thayer’s
TERTIALS – 3.5; the solid interiors are a tad paler than normal, but still concolor with the covert markings; this is seen on many Thayer’s and, in Calif, would not get me excited about a possible Kumlien’s
TAIL – 4; there no evidence of a pale shadow band or unusually large pale tips– what you see here is pretty typical. Actually, most Thayer’s have more pale baring at the base of the outer rectrices, producing a more banded rather than solid tail look.
COVERTS/BODY – 3.5; some Thayer’s can be positively frosty here, close to a 2; this bird is not a dark checkered as some, but the amount of white vs brown is nothing abnormal.
BILL COLOR – 3; only because the good photography is picking up the dusky red tones; in the field I’d probably call it a 4; again, nothing unusual;
HEAD/BILL SHAPE AND SIZE – 3; this feature varies a full point between males and females; this bird feels like a female Thayer’s, based on the refined bill and small gonydeal angle; note the elongated face toward the bill, typical of Thayer’s. Kumlien’s/Iceland have steeper foreheads and more dove-like heads.

So the total score is 25. I imagine West Coast birders would call this a Thayer’s quite comfortably.

Food for thought. A Bill Allan photo of the bird in question attached. Other pics are on this blog if you care to trawl back.

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