Photo 3: LBBG sub-adult, August 22 2002, Missouriweg Maasvlakte, the Netherlands. 

P10 has only a small mirror and the primary moult stage in this bird is advanced compared to true adult birds in the colony: P4 is fully grown, P5 is just longer than P4 and P6 is missing. P7 is old, brown bleached and worn at the fringes. The complete median covert row has been replaced. Bare parts resemble adult LBBG. Note the old greater and lesser coverts, which are worn and the grey tone has faded to pale grey-brown.