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adult California Gull

December 1, 2012. Davis, Calfornia. Photo by Steve Hampton. Two typical adults (and four sets of primaries). The red gape line is often seen.
February 4, 2013. Davis, Calfornia. Photo by Steve Hampton. The red gape line becomes obvious in most birds as the winter progresses.

Underwings from eighteen individuals. 11/18=61% have a black line separating the mirror on P10 from the tip. Otherwise, they are remarkably similar, with virtually all of the black ending with a band on P5. All of these were taken on the same day.

Note that from a distance the white spots appear larger.


These flight shot shows the primary pattern as well as the gray undersides of the secondaries, which allows Californias to be distinguished from other western species (which are either darker or lighter here) at a great height. February 14, 2012. Davis, Calfornia. March 23, 2011. Clearlake, Calfornia.

March 23, 2011. Clearlake, Calfornia. Photos by Steve Hampton.
A basic and alternate adult side by side, which you can see in March. Note how bright yellow the legs and bill have become in the breeding-plumaged bird.

Two breeding-plumaged birds with a large male Herring Gull (still with some winter streaking) in the background. It's not apparent in this photo, but most lighting conditions show California Gull to be obviously darker-mantled than Herring and Ring-billed Gulls.

Another typical adult, already in breeding plumage in March.

Two more examples of primary patterns. They all show the same thing: a large mirror on P10, usually separated from tip by very thin black line (not on the left wing in Fig 6); small-med mirror on P9; black band to P5.

A typical winter-plumaged bird.

Most adults reach breeding plumage by March, some even in February. Note the winter-plumaged adult on the left. Also, there are two first cycle birds in the middle and one second cycle in the upper right corner.