My concern over these pictures is the degree to which the tertials are worn and bleached. If the birds on this page and those on the juvenile page are both atlantis is it feasible that there can be birds seen within days of each other hatched in the same calendar year that can look so different? Clearly most of the back and scapulars on these birds are new whilst the tertials are bleached and worn. These birds are further on in their moult cycle than the juveniles that are only just starting their post juvenile (1st winter) moult. Can there be sufficient difference in hatching dates between individual birds of the year to account for this?
I understand that Lesser Black-backed Gulls moult much later than atlantis. If this is correct than one possibility is that the juvenile birds are Lesser Black-back Gulls. I find this difficult to believe as they were with a group of adult Yellow-legged Gulls only. They were also in an earlier state of moult than the picture of a Yellow-legged Gull published in British Birds November 1999 as a 1st winter photographed in September 1995. This bird also shows similar blackish centres to the tertials and pale barred 1st winter scapulars.
The other thing to consider is whether my 1st winter birds are all Lesser Black-backed gulls. There were certainly two adults present in the group of approximately fifty gulls that I photographed. The majority, however, were adult and sub-adult Yellow-legged Gulls. See below.
