[Maine-birds] Noah Gibb's Thayer's/Kumlien's

Noah, et alis,

At first I thought the bird in your photos too pale to be a Thayer's but a little research proved there's enormous variation in overall tone in this species (or subspecies), as there is with most, if not all, gulls.

Olsen/Larsson (Gulls of North America, Europe, and Asia) indicate the Thayer's in juvenile/first winter plumage shows a dark terminal band on the underside of the primaries, much like that seen on many tern species.  They indicate this is rare on Kumlien's.  The bird in your photo definitely shows this mark, so I suspect you can give your bird tentative Thayer's status based on that bit of info.

You are aware, I'm certain, that the status of the Thayer's is still unresolved.  Many authors still wonder if it isn't the darkest cline in three subspecies of Iceland Gull.  Olsen/Larsson treat the Thayer's as a qualified species, qualified until research better defines the relationships of these three forms.  These authors state the amount of hybridization between Thayer's and Kumlien's is unknown.  However they include a large breeding range for Kumlien's adjoining that of the Thayer's.  This would seem to negate the notion that the Kumlien's is a hybrid between Thayer's and Iceland, as there would need to be virtually 100% hybridization on the defined breeding area of the Kumlien's.  Which is presumptuous at best.  I feel the hypothesis that these three are different forms of the same species, Iceland Gull, will prove to be the case.  I'm not, however, an expert on taxonomy and my opinions are based on reading only.  It would be good if we could hear from someone with knowledge of DNA analysis, or further research in the remote breeding areas of these three.  Noah's post from yesterday is reproduced below for those who might want to look at his photos.

"Noah Gibb <voodoochitlins@yahoo.com> Feb 02 06:01PM -0800  

"Below is the link to several photos of the bird found by Bill Bunn in Portland that I saw at Mill Creek in South Portland today. On some of the flight photos you can see dark outer webs on primaries 6-10, although they may be less bold on P10 and P6. 1st cycle Kumlien's can show these webs I believe with strongest contrast on P7-P9, but I don't know that that would mean non existent contrast on P6 and P10. You can see on this 1st cycle bird at rest that the tertials are mostly dark which is a good mark for a Thayer's. Most of the secondaries (seen in flight) are dark, but not all. This bird also has a good tail band on it, but Kumlien's can also show that. I think this bird looks overall throughout the body and head too pale for what one would expect for a 1st cycle Thayer, but maybe it is bleached out at this point?
 
"I am not going to spend more time right now getting in to confusing details with gull ID that I don't fully understand, but in my opinion, this bird shows characteristics of both Kumlien's and Thayer's, but maybe those two species always share things in common. Maybe we can call it Larus Bunnus?
 
"Anyone's thoughts on the ID of this gull are welcome!
 
"http://www.flickr.com/photos/ngibbbirds/12279719254/
 
"Bird haahd,"

Cheers,

BAB

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Bruce Bartrug
Nobleboro, Maine, USA
bbartrug@gmail.com
www.brucebartrug.com

The world is a dangerous place, not because of those who do evil, but because of those who look on and do nothing.  - Albert Einstein

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