glaucescens Glaucous-winged Gull & Western Gull occidentalis

(last update: 22-12-2016 )

Coordinators:
Alvaro Jaramillo
John Cant
Mars Muusse

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4cy / sub-ad Jan
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Western Gull occidentalis sub-adult, December 12 2016, Pt. Pinos, Pacific Grove, Monterey Cty., California, USA. Picture: John Cant.

2nd cycle or 3rd cycle bird. Ageing can be hard, as some Western Gull retain a very retarded plumage in 3rd cycle, including brown primaries lacking a mirror on P10 and largely brown wing-covert panel. Even the secondaries may be very 2nd gen-like, with dark centres and thin white tips. See e.g. this banded bird 1176-08623.

This bird may well be another retarded 3rd cycle, although the secondaries in this bird have a 2nd gen-like look: brown centres with thin white tips are visible below the greater covert row. Also the primaries are dull brown lacking any tips and no mirror on P10 (but a view on the innermost primaries would be welcome). The rectrices are of no help either: largely brown lacking a white tip, no sharply demarcated blackish centres.

Despite all these indications for 2nd cycle, the limited head streaking and white underparts, the wing-covert panel with vermiculated greater coverts and all grey scapular region may be strong pointers for 3rd cycle. Anyway, 'sub-adult' nicely covers such birds.