juvenile "Kumlien's Gull"

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juvenile "Kumlien's Gull" Iceland x Thayer's hybrid
	Fig 1) This is a classic hybrid, often called a "Kumlien's Gull". 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. December 22, 1998. SF Bay Area, CA. Photos by Mike Rogers, copyright 1999.

Fig 2) Note the lightly streaked auriculars and the pale marked tertials, as well as how much white is present in the upperpart pattern. That's a Herring Gull at right. February 24, 1998. SF Bay Area, CA. Photos by Mike Rogers, copyright 1999.

Fig 3) This is the same bird as Figure 2 above. In flight, note the tiny marks at the tips of the inner primaries, never seen on a normal Thayer's. The tail also has a lot of patterning for a Thayer's. February 24, 1998. SF Bay Area, CA. Photos by Mike Rogers, copyright 1999.

Fig 4) This bird is at the Thayer's end of the spectrum and resembles a typical Thayer's Gull, but notice the bill color. Must be some Iceland genes creeping in. Also note the very light tertials. This one seems to be moulting out of its juvenile scapulars (on the early side; most Thayer's stay in juvenile plumage into Feb or March). Feb 1, southern Calif. Photo by Don DesJardin, copyright 1998.

Fig 5) I originally found this bird, and it struck me as whiter and more petite than any Thayer's I had ever seen. I had trouble aging it and others have said it's anything between juvenile and second winter. The obvious strikes against pure Iceland are the dark tertials on a pale bird, the dark secondary bar (barely visible on the distant wing), the solid areas to the tail, and the dark primaries. Structurally, it's more toward the Iceland end of the spectrum. February 10, 2000. Yolo County, CA. Photos by Bruce Webb, copyright 2000.

Fig 6)Here the contrasting dark tertials are evident. The bill was black at the tip, then gray to the base, except flesh at the base of the lower mandible. Despite the appearances of this photo, the bird was nearly the same size as adjacent California Gulls, though with a more rounded dove-like head and shorter, slimmer bill, and was also slightly smaller than an adjacent Thayer's Gull. Yolo County, CA. Photos by Bruce Webb, copyright 2000.