Black-tailed Gull (crassirostris) / ウミネコ / 괭이갈매기

(last update: December 2015)

Black-tailed Gull (crassirostris) sub-adult, August 08 2013, Hachinohe-shi, Aomori Prefecture, Japan. Picture: Shigeo T.

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Black spots on some secondary centres indicate sub-adult bird. Bird in complete moult: P1-P5 new (black on P3 and onwards), P6 growing, P7 missing, P8-P10 old. While P6 is growing, the moult in the tail has started: central tail feathers have been shed. This tail moult will develop centrifugal, i.e. from the central tail feathers outwards. Soon (within a week) moult in the secondaries will start as well, initiated at the outermost secondary S1. Note white tips on old rectrices.