Curious mystery gull

What do YOU think?

It’s part of the challenge.  I regularly tell folks the more Gull species you can identify in a flock, the more often you’ll find tricky ones too.  Skills definitely go up but so do the challenges.  This was a fascinating bird.

Field impression:

Had a strong  juvenile Caspian Gull feel on first view.  Head and bill shape especially and the retained juvenile scapulars only have a narrow fringe.  I did flirt with juvenile fuscus briefly.  It was easily the most aggressive gull in its area.  Thus head and bill structure etc and striking tail pattern (Caspian-like), juvenile scapulars, longish wings and behaviour all suggested Caspian. However in flight it has big primary window, rather smokey-brown looking underwing covets, though underside of primaries looks quite whitish in the video.  Greater coverts and tertials more Herring Gull like overall.  Working hypothesis as argentatus x cachinnans?  Back there on Saturday, hope it’s still there.

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About Martin Garner

I am a Free Spirit
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4 Responses to Curious mystery gull

  1. Johnny Allan says:

    Not quite right for a Caspo is it, hybrid Caspos are out there so why not Caspo x Herring Gull ?

    • Martin Garner says:

      Hi Johnny

      I agree with you sentiments and that was my best hypothetical conclusion too. Had hoped it would show again y’day but no such luck. Had it been in aug/sept I think it could have easily gone down in notebook as juv Caspian

      Martin

  2. Jan Jörgensen (JanJ) says:

    Hi Martin.
    Certainly not a Caspian Gull (it wouldn´t pass as a Sept juvenile either), to mention a couple of reasons, as you yourself do – such as juvenile plumage at this time of year, structure, inner prim window, tertial pattern with slightly notched edges in combination with the pale edge reaching the greater coverts, greater covert pattern – although variable – the pattern on this one would be wrong for Caspian. Although rather Caspian like, the bill seems to be rather thin and somehow on the short end but that could be due to quality of the film. At first some thought of a LBBG emerged. However probably more in the line with a possible Caspian X Herring?
    One example of such a hybrid can be seen here:

    http://www.netfugl.dk/pictures.php?id=showpicture&picture_id=45928
    http://www.netfugl.dk/pictures.php?id=showpicture&picture_id=45930
    http://www.netfugl.dk/pictures.php?id=showpicture&picture_id=45929

    Cheers

    Jan
    Sweden

  3. Jan Jörgensen (JanJ) says:

    Might I just correct myself – on the last sentence. “One example of such a possible hybrid”…

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