Opinions sought on this Gull

[Dave Brown]

Hi All,

I've been actively watching,studying and photographing gulls in Newfoundland for over 10 years. Every now and again, you get one that is just puzzling. I'd appreciate any ideas or comments on the following bird. The last 4 gull photos down is the gull in question.

http://birdingnewfoundland.blogspot.com/2009/12/kumliens-gulls-of-stjohns.html

Also for those interested there are a bunch of photos and commentary about dark winged adult Kumliens Gulls in St.John's Newfoundland.

Thanks,

Dave Brown

[Brian S]

Hi Dave

I am no expert on Thayer's/Kumlien's, but I have read a lot and examined many photos. Like you, I find the last gull confusing - there seems to be too much black and too little white (is it full ad?), but still the structure seems better for Thayer's (or a hybrid? with smith?).

The first of your Thayer's-type gulls does look very much like a Kumlien's/Thayer's with what Howell would call a 'stage six' primary pattern). Using Steve Howell's wingtip scoring system (Alula vol.9 2001), it scores 0-5-5-5-5-3 and the tone of the black on the primaries I would judge as being high. It resembles a Thayer's more than a Kumlien's, and may well be a backcross (Thayer's/Kumlien's) hybrid, but you can't rule out Thayer's.

Brian S