By October, 1cy LBBGs born in the Maasvlakte colonies (51.58 N, 4.02 E) and further south may show extensive wear in the scapulars (see e.g. c3 and c4), tertials and (especially in the inner median and greater) coverts; compared to the later hatched 1cy birds from Scandinavian colonies. When the jizz of these LBBGs match with Yellow-legged Gull (L. michahellis), it may be difficult to separate standing or resting birds. Best clues are the advanced replacement of coverts in L. michahellis, combined with a nearly complete 2^nd generation back and old abraded juvenile wing coverts (see the michahellis section). 1cy LBBGs in October normally have the covert moult not as advanced as in michahellis, the abrasion is often confined to the tip fringes and the outer greater and median coverts look pretty fresh and in many cases the tail has a white fringe, which is often worn a way in michahellis. There is an overlap in these characteristics and some birds are better left unidentified until they start preening. Then of course, tail-band and inner primary pattern are clues to distinguish between michahellis and graellsii.