Photo 9: LBBG sub-adult, April 16 2001, Maasvlakte, the Netherlands.

In third summer (4cy), bare part coloration starts to come close to adults. But still, in the coverts many immature feathers can be seen. Some tertials show spaghetti pattern or otherwise are grey with a central black mark. Compared to full-adult LBBG, the tips of the primaries are smaller (though some adults may show small primary tips as well; not only in fuscus or intermedius, also in Dutch intergrades. See e.g. this 10cy LBBG in the Maasvlakte colony). If present, the white mirror in sub-adult LBBG is smaller than in full-adults. In the picture, the small white mirror on P10 can just be seen; the borders of the spot hardly reach the edge of inner-web. The bill shows a distinct black bill-band. Black markings in the tail might be present in sub-adults but not necessarily; some 4cy LBBG show an entire white tail.