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|Fig 1) This is a paler Kumlien's, nearer the glaucoides end of the spectrum. Note the very light markings in the primaries and tertials, patterned tail, and extensive white in the coverts and scapulars. On the t-k-g scale, I scored this bird an 11. January 22, 2012. Saginaw River, Michigan. Photo courtesy of Dan Duso.|
Figs 2 and 3) This extralimital record from California is quite pale and appears
to fit glaucoides.
Note the petite struture of the head and bill in comparison the Glaucous-winged Gull
in the background. This bird's bill was also significantly more petite than nearby
Note, however, the brownish wash to the outer webs of the primaries in Fig 3 below, producing a shadow of a Thayer's effect. The fact that it is darkest on the outer primaries may indicate kumlieni. This issue is discussed further here.
February 2, 2012. Fort Baker, California. Figure 2 courtesy of Steve Hampton. Figure 3 courtesy of Mark Forney.
|Fig 4) This is a mid-range "Kumlien's", with subterminal arrowhead marks in the primary tips. Compare the bill size and head shape with the Herring Gull behind it. On the t-k-g scale, I scored this bird an 18. March 23, 2011. Clearlake, Calfornia. Photo courtesy of Steve Hampton.|
Figs 5-7) This nicely patterned bird with petite structure fits well inside
the Kumlien's camp. On the t-k-g scale, I scored this bird a 16.
This bird has been accepted as an Iceland Gull by the California Bird Records
December 22, 2007. Davis, California. Photo courtesy of Steve Hampton.
Fig 8) It's a "pale Thayer's Gull", a "Thayer's with Kumlien's genes", or a "Kumlien's Gull"
depending upon your taxonomic perspective. See this page for
two different taxonomic point of views.
On the first diagram, I would put this one between Thayer's and Kumlien's.
On the second diagram, I would put it between Thayer's and Iceland, but closer to Thayer's.
I would say it is not a pure Thayer's because of the combination of bi-colored bill,
petite bill, extensive white in the scaps, coverts, and tertials (and probably the tail too),
generally pale ground color, and extensive pale edging to the primaries.
On the t-k-g scale, I scored this bird a 16.
January 13, 2012. Coeur d'Alene, Idaho. Photo courtesy of Lisa Hardy.
Figures 8-11 are similar birds.
Fig 9) Again, this bird falls between classic "Kumlien's" and Thayer's.
Note the petite bill and dove-like head of Iceland, as well as the largely white
but patterned tertials. The primaries, however, are far to dark for Iceland (glaucoides),
yet too washed out for Thayer's. On the t-k-g scale, I scored this bird a 20.
December 22, 1998. San Francisco Bay Area, California. Photos courtesy of Mike Rogers.
Figs 10 and 11) Another very white, pale Thayer's-type thing. This bird is distinctly
paler than a normal Thayer's, but fairly similar in flight. Note the extensive
pale edges to the primaries. On the t-k-g scale, I scored this bird a 20.
December, 2008. Davis, California. Photos courtesy of Steve Hampton.
|Fig 12) Note the pale ground color, extensive white in the scapulars and greater coverts, semi-solid tertials, pale Thayer's-like primaries, and bi-colored bill. This bird is firmly to the left of Thayer's. On the t-k-g scale, I scored this bird an 18. January 22, 2012. Clarkston, Washington. Photo courtesy of John Walter Hanna.|
|Fig 13) That's a smithsonianus Herring Gull on the left, and a rather petite pale Thayerish thing on the right. The extensive pale in the upperparts, tertials, and primaries edges suggest something to the left of Thayer's. March 8, 2000. San Francisco Bay area, California. Photo courtesy of Mike Rogers.|
|Fig 14) This is the same bird as above. In flight, it looks like a typical Thayer's Gull, with a dark tail band, outer primaries, and secondaries. The tail seems to have a pale "shadow band" within the dark band, another sign of Kumlien's influence. On the t-k-g scale, I scored this bird a 19. March 8, 2000. San Francisco Bay area, California. Photo courtesy of Mike Rogers.|
Figs 15 and 16) This bird is toward the Thayer's end, but it has patterned
primary tips, rather pale tertials, a washed-out tail, and no contrasting secondary bar.
It may pass for a Kumlien's Gull on the East Coast.
On the t-k-g scale, I scored this bird a 20.
February 23, 2012. Petaluma, California. Photo courtesy of Floyd Hayes.
Figs 17 and 18) This bird is essentially a paler Thayer's with large pale edges to the primaries. Most interesting is the tail, which shows a broad distal "shadow band", as if the outer half was dipped in bleach. On the t-k-g scale, I scored this bird a 23. February 18, 2012. Davis, California. Photo courtesy of Steve Hampton.
Fig 19) This bird is typical of the "Iceland Gulls" in California. It has nicely patterned tertials and
tail, but is more Thayer's-like in head and bill structure. On the t-k-g scale, I scored this bird a 17.
January 10, 2013. Riverside County, California. Photos courtesy of Steve Ritt.