I've been seeing lots of Thayer's and Lesser Black-backeds lately and so it was nice to get on this Glaucous Gull on Sunday:
|Glaucous Gull (3rd cycle). Lake County, IL. 08 Dec 2013.|
Other highlights for the day included this adult Thayer's:
And this 3rd cycle type and 2nd cycle type Lesser Black-backed, respectively:
But perhaps most intriguing were these "white-winged" adult Herrings:
Unlike the Northeastern United States and Newfoundland/Labrador, American Herring Gulls on the Great Lakes and the Western United States typically show a limited amount of white on the outer primaries. On average, the so-called "Great Lakes" birds show a single mirror (on P10) and smaller white apicals, and tend to average smaller body proportions.
So seeing birds with this much white in the wingtips in my area (Illinois) sends up red flags, inviting some confusion with Thayer's. But note the staring pale-yellow eye, and the yellow-orange orbital ring. This is not expected on THGU, which shows a purplish orbital.