After completion of the post-juvenile moult a vast majority can be sexed based on the pattern and coloration of the underside of PP and upper wing coverts. Coloration of mantle, rump and head is useful as well. Note that intermediates may occur, mainly involving 1cy males and adult females. Make sure to use more than one criterion, and always start with ageing.
Male, 1cy, November. Quite distinct margin between darker grey and white under PP and SS. Note that this is a pale (female-like) individual, and most males show more distinct contrast than this. 
Male, 1cy, November. A rather dark male with blotchy GC and more extensive black than usual in MC and LC, resembling a pale female. Most 1cy males appear whiter than this, rather similar to adult males. 
Male, 1cy, November. A typical young male with white in both inner and outer webs of PC. Adult females may approach this pattern but never show this extensive white in GC, MC and LC.
Male, 1cy, November. In males, many or most of the feathers of the head and neck, including crown and ear-c, show white bases (tipped brown or buff-brown).
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