There has been much chat and debate – some in public some not. Here is the latest from Jim Dickson, who has probably spent longest with the bird in the field.
Just a bit of feedback on the Dunbeg Gull.
Many thanks to everyone who has contributed to the discussion into trying to resolve the identity of this individual…this has been very much appreciated.
It certainly looks like from all the feedback, which, despite this bird showing many positive Thayer’s features it now seems most likely that the dark plumage shown by this bird is within the range of a dark juv Kumlien’s Gull, albeit at the extreme end of the range. This coupled with features picked up on by several folk i.e. pale based scapulars, tertials being on the pale side and a poorly defined dark trailing edge to the secondaries indicated that this bird was unlikely to be a pure Thayer’s. Many photographs of Thayer’s Gull that were studied showed birds almost identical to the Dunbeg bird and I feel it is likely that at least some of these photos are also of hybrid types rather than pure classic juv Thayer’s. It also appears very clear that when assessing plumage and contrast (e.g. tertials/primaries) of this bird that light conditions played an important role. It was first seen and photographed by Bill Allan with very strong direct sunshine from behind and when photographed by me the following day the conditions were heavily overcast and made getting detail from flight shots in particular rather difficult.
In a UK context the Dunbeg bird may perhaps add to the knowledge of very dark juvenile Kumlien’s types and the differences from possible future ‘pure’ Thayer’s.