Albert de Jong
Larus cachinnans 2CY 260P October 21-29 2008, Westkapelle, the Netherlands. Picture: Ies Meulmeester & Walther Leers.
Green 260P and metal DN21544. Bird ringed as pullus on May 18 2007 at Jankowice Babice Malopolskie, Poland.
Note mirror on 2nd gen P10. Most of this gull looks like a 2cy Caspian Gull, even with a typical clear mirror on P10, but there are some features such as the fine dark streaking on the head, the extensively dark woolly streaking on the hind-neck, the shape of the head and the pattern on greater coverts (recalling Herring Gull), the median coverts and lesser coverts which is a bit atypical for Caspian Gull. The problem is that we don't know enough about the plumage variation in pure Caspian Gulls and therefore we can not say for certain if a gull with these features is a pure Caspian Gull or if there's any influence from other large gull species.
below: cachinnans 2CY 260P October 29 2008, Westkapelle, the Netherlands. Picture: Walther Leers.
In many ways a classic 2W bird, including mirror on P10 (while this is rather common in this plumage in Caspian Gull).
below: cachinnans 2CY 260P October 21 2008, Westkapelle, the Netherlands. Picture: Ies Meulmeester.