Thayer's Gull (thayeri)

(last update: January 22, 2013)

Thayer's Gull sub-adult, mid-January 2014, central California, US. Picture: Amar Ayyash.

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Present flock of about >600 birds (170 1st cycles, 100 2nd cycles, 40 3rd cycles, 350 adults).

Probably 3rd cycle, but may also be very advanced 2nd cycle (best to see inner primaries).

In 3rd cycle:
Typically, no contrast between wings and scapulars, all adult-like grey, but some feathers with brown wash or delicate vermiculation (but in this bird many coverts still with brown tones). Few tertials with dark centres.
3rd gen flight feathers, still much black in tail and white tips on outer primary hardly developed (but in this bird tail almost completely dark and primaries a pale brown).
Much black in bill.