Young, pale-winged gull at Lake Estes in Larimer County, Colorado (west-central USA), elevation 7500' (approx) in the foothills of the Rocky Mountains, found by Scott Rashid on 10 November 2012.
This bird was larger than accompanying California Gulls, about the size of Herring Gull, but still on the small side for that taxon. To see additional commentary and ID discussion points, and to view larger images, click on the photo (comments appear below each photo (but not in slideshow mode; use arrows to move back and forth through the photos).
Summary of my take on this bird: The set of characters exhibited by this bird taken all together is not typical of any one taxon. Unfortunately for those of us who like to compartmentalize all birds into "species" categories, this bird should be categorized as "unidentifiable".
