[obol] John Rakestraw's Gul

[David Bailey]

Russ Namitz pretty much well summarized the key points as to why 
"John's" gull is not a Slaty-backed. Slaty-backed shows a much paler eye 
(more white, less amber) and shows blotchy, spot-like brownish-gray 
markings to the head that do not show barring or feathering and do not 
terminate in a rather contrasting hood. The bill would look straighter 
sided as mentioned. The mantle would be at least a shade and a half (OK, 
I know there is no such thing, but for lack of a better descriptor) 
darker--dusky-gray rather than blue-gray. The outer primaries 
(wing-tips) would show white tips to the internal tongue-tips that in 
relationship to the each other would show the characteristic 
"string-of-pearls" subterminal white band to the black wingtips. This is 
not depicted in the photos posted by Greg, but would be seen in the 
spread wing of the bird. John mentioned that the wing-tips where similar 
to the Western Gulls. In a standing with wings folded pose, this is 
probably mostly the case. In Western x Glaucous-winged hybrids there is 
a "string-of-pearls," so beware, and also apparently in Vega Gulls this 
feature is present--though those birds would be paler-mantled than 
Western Gull. The legs and feet in Slaty-backed tend to be hot pink 
rather than dull pink, but this is one of the least reliable features 
(also true in Thayer's Gull). Russ mentioned the "pirates patch" of dark 
around the eye (I believe it was Mr. Gilson who coined this phrase back 
in the wonderful days of rotting cookies at the Sauvie Island Pellet 
Plant) which should be obvious on an adult or third-winter Slaty-backed.

Hope this helps.

Happy Gulling,

And, if you have read this far, a question for the lariphiles out there: 
Do our typical Herring Gulls show more than one mirror to the primaries, 
or is a single large "moon" on P10 typical with the other primaries 
showing only white tips?

David

David C. Bailey
Seaside, Oregon

baileydc at pdx.edu