Slaty-backed Gull (schistisagus) / オオセグロカモメ / 큰재갈매기

(last update: December 2015)

Slaty-backed Gull (schistisagus) 2nd basic moult / 2CY September

Birds in the last stage of the first complete moult, replacing all flight feathers for 2nd generation. The new outer primaries are already visible, also in resting birds. Outermost P9 and P10 still have to grow to full length.
Moult gaps in the wing-coverts are closed, when the central greater coverts are replaced and the small feathers in the carpal edge are renewed.
Secondaries and rectrices are in active moult; the secondaries are replaced by two moult waves. One moult wave from the body outwards, and another moult wave from S1 inwards. These two waves will meet at about S16-S17. Tail feathers are replaced centrifugal; the central feathers are dropped first and the outer rectrices last in line.