Not seeing the kumlieni for the hyperboreus- an id. put to rest

A first-year white-winged gull turned up last year at Long Beach, Stratford, CT It was well photographed and identified by various observers as a Glaucous Gull, then perhaps a hybrid. However, the pix show a bird that fits with kumlieni, albeit a very big one! I had mentioned my opinion at the time, but the bird continued to be discussed ad nauseum with some observers believing the bird to possibly be a hybrid, an opinion I was at odds with since there didn’t seem to be any hybrid characters. Although it returned this winter, it was still reported as a Glaucous Gull despite it having dark-washed primaries, a feature never shown by hyperboreus.

After a careful analysis of the photos, I concluded the pro-Glaucous features to be:

  • It was big!

The pro-kumlieni features to be:

  • It didn’t look like a Glaucous Gull!

Thankfully, it returned this winter in it’s second-winter plumage sporting the expected dusky webs to the outer primaries diagnostic of kumlieni. The bird’s large size was apparent, but not outside the range of kumlieni and I think many observers got too hung up on size and didn’t really assess the bird’s plumage features which, as shown are perfectly kumlieni.

_MG_5407

Note the rather slim body and pointed wings and proportionately large eye. The solid, dusky tail and dusky outer webs to the outer primaries are diagnostic of kumlieni. The large mirror on P10 is visible in the enlarged version._MG_5424

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One Response to “Not seeing the kumlieni for the hyperboreus- an id. put to rest”

  1. Tom Ennis Says:

    Hi Julian,

    First big mistake people make in dealing with Glaucous/Iceland Gulls is to base ID on size. Iceland Gulls appearing in Ireland are mostly L. g. glaucoides but we do get the occasional L. g kumlieni. The latter are often set upon by the optimists who endeavour to add L. thayeri to their Irish Lists. What people do not realize is how variable glaucoides are in size; this covers a range from a little larger than L. canus through to as big as some L. argentatus argenteus. Admittedly a smaller bird than the American Herring Gull but still sizeable.Size variance probably due to males/females but perhaps different populations(?) The “gentle” appearance of the facial features, suggested in some books is again variable with some individuals appearing quite “coarse” with quite large bills. This coupled with the fact that the pink bill with black tip is often regarded as the badge of the immature Glaucous Gull can lead the unwary down the wrong path. Even First Year Icelands by February can show this feature. If the present bird turned up in Ireland we would have no hesitation in identifying it as kumlieni.

    Hybrid theories are the last resort of the baffled.

    Continuing to enjoy your Birding Journal.

    Best,

    Tom

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