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Thayer’s – Iceland Gulls ID field marks; plus ID case

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  • Thayer’s – Iceland Gulls ID field marks; plus ID case

    Hi All,

    I have to admit that I tried already to check on this gull but received no feedback. I should came here first but as I am away from my computer for a few days, and do not want to wait, I will provide a few links to photos I had uploaded to my site earlier. I got some great help here in the past so I hope some people will share their opinions now as well. I am not convinced yet that this gull can be positively ID (mean without doubt) but I would like to be proven wrong.

    Standing
    http://www.pbase.com/mbb/image/141345787
    Head
    http://www.pbase.com/mbb/image/141345790 , http://www.pbase.com/mbb/image/141345796
    Tertials
    http://www.pbase.com/mbb/image/141345794
    On wing from above
    http://www.pbase.com/mbb/image/141345799
    On wing
    http://www.pbase.com/mbb/image/141345784
    http://www.pbase.com/mbb/image/141345802

    OK Thayer’s – Iceland (nominate and Kumlien's) Gulls and, of course, hybrids. I have no field experience with these gulls but done some reading recently only to find out that situation looks messy. Not only there are divided opinions on their taxonomy but it seems that too often one gull on photo is ‘believed’ to be different species/subspecies when check by different people. So chance to get positive ID often does not look too promising. Only recently I decided to stop turning my head away when I see some juvenile gulls but am seriously thinking about going back to this habit as in my case if I cannot positively ID an individual bird (or have somebody else to do that) my observations are worthless and practically waste of time. I do not care how many different birds I see during the day or saw in the past, or will in the future - I am not a ‘lister’. I am writing this info about myself only to show that I have no interest to look for ‘rarities’.

    Why I have problem with this gull - I will not list location now as I do not want anybody draw any suggestions from that. This is to me purely theoretical - this gull is what it is and where it was find is not going to change the species that it belongs to, as is not going to change the sex for that matter. First it is very ‘petite’ (tad bigger than Ring-billed; smaller than Lesser Black-backed; obviously much smaller than Herring); tertials are lacking dark centered pattern (field mark typically listed and well illustrated in many guides for Thayer‘s but not for Iceland), to me primaries are not really darker than brownish color on some body feathers, secondary bar is not really prominent (see flight photo from above with even lighting) etc; but perhaps I should stop lengthy description of my worries as this case might takes a second for an expert to ID this bird. Of course I would appreciate any remarks on ID of this gull; also which field marks are important and constant and which are not in Thayer‘s - Iceland identification. I am afraid that unfortunately many interesting gulls are gone unnoticed as many people are afraid to keep asking the ID questions about so many gulls they see (me included).


    In case more photos are needed I will be able to upload some more in couple of days as I am going to be away from my computer and might even have problem with checking my emails on regular basis during next few days.

    Thanks in advance

    Mark

  • #2
    Thayer's Gulls in UK

    Personally, I would not tick a Thayer's in the UK unless it was an undeniable adult. And I know I will get villified for this comment. I applaud every single questioning word of your posting, Mark.

    Comment


    • #3
      Originally posted by Firecrest15 View Post
      Personally, I would not tick a Thayer's in the UK unless it was an undeniable adult. And I know I will get villified for this comment. I applaud every single questioning word of your posting, Mark.
      Many thanks for your mental support (I need that for sure); I was hoping that I am not the only one who keeps asking these questions quite often. Unfortunately I read too often that IDs of some gulls were based on: ‘I believe this is an X gull’ and no even one word of explanation why. Well, we all have believes; I am sure people from some uncontacted tribes still believe that Earth is flat, I personally met many people who believe that Earth is few thousand years old but positive bird IDs should be done based on some field marks that can be verified by others rather than trusting somebody’s believes and only believes (without presenting some supportive data).

      I was going to post this reply together with a photo showing size comparison but this is not going to happen right now so I did not want to wait. I might have a chance late at night (post additional photo) although I am already loosing faith (!) that this will help. From now on I am going to not even look in the direction of these gulls and if I accidentally take a photo of one I will dump it in the folder ‘seagull’ – the perfect ID name for them.

      All the best,

      Mark

      Comment


      • #4
        Originally posted by mbb View Post
        Many thanks for your mental support (I need that for sure); I was hoping that I am not the only one who keeps asking these questions quite often. Unfortunately I read too often that IDs of some gulls were based on: ‘I believe this is an X gull’ and no even one word of explanation why. Well, we all have believes; I am sure people from some uncontacted tribes still believe that Earth is flat, I personally met many people who believe that Earth is few thousand years old but positive bird IDs should be done based on some field marks that can be verified by others rather than trusting somebody’s believes and only believes (without presenting some supportive data).

        I was going to post this reply together with a photo showing size comparison but this is not going to happen right now so I did not want to wait. I might have a chance late at night (post additional photo) although I am already loosing faith (!) that this will help. From now on I am going to not even look in the direction of these gulls and if I accidentally take a photo of one I will dump it in the folder ‘seagull’ – the perfect ID name for them.

        All the best,

        Mark
        Not really sure where this is going but maybe use this semi-quantitative method of diagnosis:

        http://www.tertial.us/gulls/tkg.htm

        Its drawing lines in the sand, but if you insist on wanting to add discrete names to dynamic phenotypes then lines have to be drawn somewhere...
        Dept. of Zoology, University of Cambridge, UK

        My website - Neotropical Bird Club -Tropical Forest Research - Punkbirder - Wikiaves

        In natural science the principles of truth ought to be confirmed by observation. — Carolus Linnaeus

        Comment


        • #5
          Originally posted by Alex Lees View Post
          Not really sure where this is going but maybe use this semi-quantitative method of diagnosis:

          http://www.tertial.us/gulls/tkg.htm

          Its drawing lines in the sand, but if you insist on wanting to add discrete names to dynamic phenotypes then lines have to be drawn somewhere...
          Interesting but think I'd drop head shape and bill colour - on second thoughts those features might actually triangulate the plumage features which I suspect are not independent (ie most birds which score 1 on primaries will score 1 on tertials and so on) - does this matter?

          cheers, alan

          Comment


          • #6
            Originally posted by Alex Lees View Post
            Not really sure where this is going but maybe use this semi-quantitative method of diagnosis:

            http://www.tertial.us/gulls/tkg.htm

            Its drawing lines in the sand, but if you insist on wanting to add discrete names to dynamic phenotypes then lines have to be drawn somewhere...
            Alex, thank you a lot for this link to interesting site I was not aware of. What is important, at least to me, it is a fact I now accepted that these gulls, way too often, cannot be ID positively from the photos or even in the field. I am not interested to catch and take a DNA sample from everyone of them. And this acceptance of reality is perfectly fine with me as it is nothing new. Long time ago, seems like in another life, but for quite long time I studied taxonomy of some beetles; the most interesting specimens were those who I had to collect, prepare their genitals and study those under the microscope. Only then I was able to IDed these tiny critters. I never missed this part as I rather prefer to study living animals in their natural habitats. So, I can tell you now that for example ‘Thayer’s type’ gulls (as many other birds, e.g. some flycatchers) are out of my reach. If I or somebody else cannot ID them but only speculate to their origin this is not my cup of tea. For sure I do not need to add to my headache by having several different IDs from several different peoples and do not know what to do with it. From the feedback I already got, or practically lack of it, I already know that these gulls are not for me. I never did and I do not plan to have interest in gull taxonomy, not to mention that I do not have knowledge or resources to study their DNA. BTW I am still going to enjoy watching them in the field.

            Again, as it should be clear by now, I do not believe that I can ever be fully convinced of any ID of this gull but if somebody wants to see the size comparison here it is: the ’seagull’ next to the Ring-billed Gull. It is always interesting to hear others opinions and maybe take a new look at the old problem.

            One more time thanks to all who replied.

            All the best,

            Mark
            Attached Files

            Comment


            • #7
              I am sure others can do it better (having more experience with these gulls) so perhaps some will decide to share their score for my gull. I will score it 19 that gives the ID I thought about after first check of photos on my computer: Thayer’s hybrid (mean mostly Thayer’s but not pure). In meantime, when waiting for replies to my post during last week I checked a lot of photos and read about what other people proposed on subject how to classified these species and subspecies.

              Although I only had chance to read abstract and some reviews the result of this study seems to be very promising: Weir, D.N., A.C. Kitchener, and R.Y. McGowan. 2000. Hybridization and changes in the distribution of Iceland gulls (Larus glaucoides/kumlieni/thayeri). J. Zool., Lond. 252: 517-530. (wish I had copy and could read full paper). If this is a case the ID of Thayer’s/Iceland (with all of hybrids between - “Kumlien’s Gulls“) will be much easier than is now.

              All the best,

              Mark

              Comment


              • #8
                Originally posted by mbb View Post

                Although I only had chance to read abstract and some reviews the result of this study seems to be very promising: Weir, D.N., A.C. Kitchener, and R.Y. McGowan. 2000. Hybridization and changes in the distribution of Iceland gulls (Larus glaucoides/kumlieni/thayeri). J. Zool., Lond. 252: 517-530. (wish I had copy and could read full paper). If this is a case the ID of Thayer’s/Iceland (with all of hybrids between - “Kumlien’s Gulls“) will be much easier than is now.

                All the best,

                Mark
                that paper can be downloaded from here:

                http://www.surfbirds.com/forum/showp...8&postcount=18
                Dept. of Zoology, University of Cambridge, UK

                My website - Neotropical Bird Club -Tropical Forest Research - Punkbirder - Wikiaves

                In natural science the principles of truth ought to be confirmed by observation. — Carolus Linnaeus

                Comment


                • #9
                  Thanks a lot Alex - your help just made my post well worth investment. BTW I truly like the quote by Linnaeus …

                  All the best,

                  Mark

                  Comment


                  • #10
                    Hello Mark!

                    I saw your gull some time ago and my first reaction was 'not one of those difficult hybrids again' This gull from Texas is not a pure thayeri to pale and structurally + billshape/size wrong - nor a kumlieni (structurally + billshape/size wrong and probably not a pure smithsonianus from what I can see on but some female smith and possible a pale variant might be a second choice? However, the hybrid theory is most likely to be considered here.
                    Hybrids considered could be thayeri x kumlieni, smihsonianus x hyperboreus (dark bill might not be a typical option for this hybrid though). The thayeri x kumlieni doesn´t seem to good - due to large bill and structure, just to open up for further suggestions...

                    Cheers

                    JanJ

                    Comment


                    • #11
                      Originally posted by JanJ View Post
                      Hello Mark!

                      I saw your gull some time ago and my first reaction was 'not one of those difficult hybrids again' This gull from Texas is not a pure thayeri to pale and structurally + billshape/size wrong - nor a kumlieni (structurally + billshape/size wrong and probably not a pure smithsonianus from what I can see on but some female smith and possible a pale variant might be a second choice? However, the hybrid theory is most likely to be considered here.
                      Hybrids considered could be thayeri x kumlieni, smihsonianus x hyperboreus (dark bill might not be a typical option for this hybrid though). The thayeri x kumlieni doesn´t seem to good - due to large bill and structure, just to open up for further suggestions...

                      Cheers

                      JanJ
                      Jan, thanks a lot for your opinion - in fact I was hoping that you will share your thoughts. At least now I might still not have solid ground under feet, it is still slippery, but I know that this gull will remain unidentified. It seems that if you want make somebody to dislike you can send him photos of this gull and ask for an ID (just kidding) - but the truth is that I did send a few requests and never heard back … In this situation your reply is even more valuable. Having confirmation from the gull expert will allow me to sleep good again.

                      All the best,

                      Mark

                      Comment


                      • #12
                        Hi,I'm a British birder with 37 years experience.We get Iceland Gulls of all ages every year in our local harour(anything from 1 to 12).You ca immediately rule out glaucoides(the nominate Iceland)because of the primaries that are way too dark for that species...or can you?
                        We ahd one bird 18 years ago that was originally ID'ed by th experts as a first year Thayer's,then they decided it was Kumlien's.It returned as a second year bird and questions were raised(we knew it was the same bird as it was in a bit of an unusual place,where no Iceland had been seen before.It has been returning every winter ever since,and a an adult has the whitest of white primaries and is every bit pure Iceland yet as a juvenile it was dark all over ,possibly slightly darker and more velvety than your bird.
                        No wonder you're confused.
                        I don't think even the experts are a hundred per cent certain.
                        The theory that the extremely dark ones are Thayer's ,the pure white Iceland and Kumlien's is a cline of crosses between the two is probably the safest of roads to go down.

                        Comment


                        • #13
                          Originally posted by Pale Male View Post
                          Hi,I'm a British birder with 37 years experience.We get Iceland Gulls of all ages every year in our local harour(anything from 1 to 12).You ca immediately rule out glaucoides(the nominate Iceland)because of the primaries that are way too dark for that species...or can you?
                          We ahd one bird 18 years ago that was originally ID'ed by th experts as a first year Thayer's,then they decided it was Kumlien's.It returned as a second year bird and questions were raised(we knew it was the same bird as it was in a bit of an unusual place,where no Iceland had been seen before.It has been returning every winter ever since,and a an adult has the whitest of white primaries and is every bit pure Iceland yet as a juvenile it was dark all over ,possibly slightly darker and more velvety than your bird.
                          No wonder you're confused.
                          I don't think even the experts are a hundred per cent certain.
                          The theory that the extremely dark ones are Thayer's ,the pure white Iceland and Kumlien's is a cline of crosses between the two is probably the safest of roads to go down.
                          Many thanks, Pale


                          Your response can truly makes somebody having a lot of thoughts about how ‘real’ are some cases of juvenile gull IDs.

                          All the best,

                          Mark

                          Comment


                          • #14
                            Hi Pale,

                            I remember that particular bird, I even twitched it at the time.

                            I seem to remember seeing some photo's of it also (perhaps in twitching, but I may be wrong?) but then it all went pear shaped each following winter as it returned.
                            I did see the Australian Black Swan as a bonus though which was called Blackie (or at least that's what the old dear called it as she chucked several pan loafs it's way).

                            Comment


                            • #15
                              Originally posted by Pale Male View Post
                              Hi,I'm a British birder with 37 years experience.We get Iceland Gulls of all ages every year in our local harour(anything from 1 to 12).You ca immediately rule out glaucoides(the nominate Iceland)because of the primaries that are way too dark for that species...or can you?
                              We ahd one bird 18 years ago that was originally ID'ed by th experts as a first year Thayer's,then they decided it was Kumlien's.It returned as a second year bird and questions were raised(we knew it was the same bird as it was in a bit of an unusual place,where no Iceland had been seen before.It has been returning every winter ever since,and a an adult has the whitest of white primaries and is every bit pure Iceland yet as a juvenile it was dark all over ,possibly slightly darker and more velvety than your bird.
                              No wonder you're confused.
                              I don't think even the experts are a hundred per cent certain.
                              The theory that the extremely dark ones are Thayer's ,the pure white Iceland and Kumlien's is a cline of crosses between the two is probably the safest of roads to go down.
                              This is really interesting. DO you have any photos of it as a juv and an adult?

                              Comment

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