Caspian Gull hybrid?

Faint hearts look away now.

A first winter gull  around the Sheffield area at the moments looks interesting to me. Saw it last night in the roost at Orgreave lakes and today on rooftop by the salubrious site of the dog tack car park at Owlerton. Also in area 2 adult argentatus Herring Gulls with orange rings on left legs (origin?). One  was ring no. 1768. Also ad and 2 first winter Yellow-legged Gulls and 2nd winter Mediterranean Gull, so far.

1st winter gull perhaps showing intermediate characters between Caspian and Herring Gull. Owlerton, Sheffield, 16 December 2011

3 Videos of same bird showing interesting characters:

Overall appearance:

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Underwing pattern and side view (use freeze frame)

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Tail Pattern while preening

Rough field notes:

At times looked somewhat cachinnans-like, others times I wondered if just odd Herring (especially when head pushes into neck and hunkered down). Quiet white front of face and centre of breast but otherwise pretty darn streaky looking. Has some moult in coverts on right side. Hard to see mantle feathers seemed almost plain grey with cachinnans- like spots. Similarly some scapular looked plain-ish greys approach classic cachinnans pattern. Horrible greater covert bar (for Caspian). Thumbnails on tertials. Horrible short legs (for Caspian). Underwing rather Herring Gull- like but tail better for mich/ cach. All details and more in photos/ video.

I asked gull guru Chris Gibbins, whose paper on tricky Caspian’s and hybrids has just been published in ‘British Birds’. His first reaction was (thankfully) he also thought the bird looked intermediate between Caspian and Herring. Whats do you think?

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About Martin Garner

I am a Free Spirit
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10 Responses to Caspian Gull hybrid?

  1. Gavin Haig says:

    What a fun bird! I thought I’d try and ‘score’ your bird using the criteria as per the latest BB article. Not that easy, but I came up with a score of 24, which interestingly puts it in the rather small overlap range between pure Casp and hybrid. Frankly, it wouldn’t surprise me if it was one. A perusal of CG’s recent blog post (on Gulls and Birds) of loads of Casps in Azerbaijan shows how variable they can be, hence why I wouldn’t be surprised! Personally I thought the underwing looks reasonably good, but yes, the legs are a bit diddy. Indeed, interesting bird, but it wouldn’t quite get my vote! :o)

    Cheers

  2. neil hagley says:

    Hi Martin. Easy to jump on the train when it’s already moving but for what it’s worth I agree. Bill looks on the heavy side, legs look ‘substantial’ and short. The shading around the eye rather YLG like. This is a good example of why it’s not always possible to put a name to every gull and why I find some comfort in passing up on the odd one at Shawell.

  3. Jim Middleton says:

    There’s been some orange ringed gulls in Scarborough, ringed at the tip by the Central Science Labs lot at Sand Hutton. Black numbers on orange ring.

  4. Jan Jörgensen (JanJ) says:

    Hi Martin & all.

    Rather easy to put yourself in the hybrid camp when seeing a gull like this. In the first video, structure becomes quite apparent, both when seen in profile and from behind, with a rather thick-necked impression making overall proportions more in line with Herring. However, the features mentioned, and as can be seen, for this bird includes some Caspian features, which imo makes it a good hybrid candidate. One should however, be aware of great similariteis to some pure Hering, such as the occasional covert moult in a few Herrings, worn tertials, greater coverts and pale heads, not to mention – rather similar bill proportions in some Herrings. Hybrids can be higly confusing and some will never be identifiable. If you for example look at an individual like this:
    http://www.artportalen.se/birds/gallery_imageinfo.asp?imageID=320970

    you are bound to be rather confused. The combination of greater covert and tertial pattern would be difficult to identify it as a Caspian – although everything else looks alright for one (I guess)

    Cheers

    JanJ

  5. Martin Garner says:

    Thanks for various responses. Gavin, well done on using the new BB paper, interesting result. Ruud Altenberg sent me helpful link on my Facebook page of an apparent hybrid. http://daarruud.home.xs4all.nl/cachinnans1m.html

    He felt the inner primaries were outside the range of Caspian on his bird, but though the inner primaries were inside range for Caspian on Sheffield bird (from what was visible on video), though he isn’t saying it is a pure Caspian. I saw it again last night, so hopefully more views and photos. be good to see it ‘long call’. I don’t think it can definitely be labelled, but real Caspian is not impossible. My own subjective feeling is that hybrid sits better for me but doesn’t mean I am right!

    Martin

  6. David Williams says:

    Hi Martin
    confirmation that orange 1768 was ringed at Seamer landfill as part of a cannon net catch as a 1st year bird on the 30 November 2007. Subsequent to that, reported from Priorslee Lake, Telford on 28 Dec 2009 roosting on ice near landfill. Yours is the third record.

  7. keith mcalpine says:

    i have posted a possible caspian caspian hybrid on BF ID page thought it might interest you.

  8. Jan Jörgensen (JanJ) says:

    Hi Keith.
    Funny you should bring this up as I just considered to do the same – meaning showing your gull as an example of what I belive could as well prove to be a pure Herring. I can however, see where Lou (on BF) is comming from – when he claimes Caspian involment. It´s imoportant to realise how variable a Herring actually can be, thereby not saying that the whole range of variability is perfectly known to us, or for that matter, easily excluding possible hybrid origin for certain individuals. Keth´s gull doesn´t strike me as a hybrid in the first place since it would be difficult to exclude a pure Herring.

    JanJ

  9. Jan Jörgensen (JanJ) says:

    For show!
    Another one with cachinnan like longcall by Hannu Koskinen. Good opportunities for detailed studies here!

    http://hjkoskinen.kuvat.fi/kuvat/Gulls+-+latest/1cy+cac-arg/

    Question mark for this August 1cy.Right or wrong?

    http://hjkoskinen.kuvat.fi/kuvat/Gulls+-+latest/1cy+Caspian+Gull+or+not/

    JanJ

  10. Pingback: Gleaming white armpits | Birding over my head

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