Iceland Gull with dark wing edges

This sub-adult Iceland Gull has been on Kilkee beach for the last two weeks along side the American Herring Gull.  I see Richard Bonser made comments online about it having a black spot on the left wing and dark edges to the outer primaries. I was intrigued, so I made sure to take shots and study the bird a little closer during my visit to see the AMG.  The bird had no black spots in any of the primaries, but a gap in the feather of P10 on the left wing and the edges of the wings were dark as Richard stated.  But most of the darkness on the under primaries was caused by sand and dirt that the bird picked up on the beach, as it scrambled for food with the other gulls. There was however some dark lines on the outer trailing edge of the primaries on the upper and lower of both wings that is not consistent nor the standard for Iceland Gull Larus glaucoides, but it did not appear to be anything else either such as Kumliens Iceland Gull from Canada Larus glaucoides kumlieni ?  I think it is just one of those that we will have to let go unless genetically tested.

 

 P10 is showing a lot of dark edges especially at the tip

 Here one can see the gap in the outer feather of P10

 Once again an indentation on P10 of the left wing

 The underside of P10 with sand spattered along the primary and dark edges to the outer tip

 Here the outer edges of all the under primaries appear dark

3CY or Sub adult Iceland Gull at Kilkee John N Murphy