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A blog mainly about birds and birding, to supplement my website www.gobirding.eu. I shall add new posts on an ad hoc basis as and when I have something I think is worth sharing, whether that’s an interesting bird, something I’ve learned, perhaps about identification, or something that’s aroused my curiosity. Often there will be questions, some of which you might be able to answer... please use the comments!

Saturday, 29 September 2012

Another non-juvenile immature skua

Following my last post about a first-summer Pomarine Skua here's another immature skua that's not a juvenile.  This one was seen on a sea watch from Sheringham in Norfolk.

I'm not completely sure if it's first-summer or second-summer.  Whilst it had a dark forehead and forecrown covering pretty much the same area as the dark on an adult pale-phase Arctic Skua it wasn't at all well-defined and didn't really recall the dark cap of an adult.  From what I've read a second-summer would be better defined than this, but do you agree that it must therefore be first-summer?  Are there any other pointers visible in the photos that enable us to age it?

And what about the species.  Having discussed it with Rob I think it's an Arctic, and that's what I thought it was in the field too.  While I was watching it I did wonder if Long-tailed could be ruled out, and I'm still not completely certain I've adequately eliminated that possibility.  What do you think?  Is there anything in the photos that clinches it beyond doubt?













probable first-summer Arctic Skua, Sheringham, 27th September 2012

2 comments:

  1. Hi Dave - not easy!
    I'd go Long-tailed Skua based on
    overall cold tones drained of colour.
    3 tone upperbody and wing colour - pale rump, greyer body and dark tail (tail being the darkest part of the whole plumage).
    Long tail projection that appears blunt at the end.
    Quite 'messy' underwing pattern.
    Photo four clearly show two very prominent primary shafts - also not ideal because there are two more lesser shafts on the 3rd and 4th primary, but how prominent would these be in the field? The rest of the photos show the primary shafts as a kind of wedge confined to the outer two.
    Photo 6 gives quite a shearwater-like impression with the hand longer than the arm.
    Slim body shape with toned chesty impression as if the bird has no body fat esp photo 8.

    the only thing that bothers me somewhat is quite extensive underwing primary flash indicating Arctic.

    Yes interesting could be 1st summer but don't even want to go there!
    Josh

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  2. Thanks Josh! Interesting to see you come down in favour of Long-tailed. I nearly convinced myself it was a Long-tailed at one point when I was reviewing the photos but then after chatting to Rob who favoured Arctic (just from seeing some of the photos) I found a photo of a first-summer Arctic that looked astonishingly similar. I'm far from sure though, especially if a skua-fan like you is leaning towards Long-tailed!

    It's a shame the photo quality isn't a little bit better. I think it's difficult to be clear how pointed the tail projection really is, but it seems to me to be rather less blunt than on at least some Long-tailed. The upperwing flash is somewhere in between textbook examples of each species but as you know, both species can vary in extent.

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