Announcement

Collapse
No announcement yet.

Separating argentatus from argenteus - seeking opinions/information

Collapse
X
  • Filter
  • Time
  • Show
Clear All
new posts

  • Separating argentatus from argenteus - seeking opinions/information

    Where I live in E Devon argentatus (ie. 'Scandinavian') Herring Gull is a rare bird. It is on the county 'A' list, requiring a full description. I've seen 2 adults locally - on the Axe estuary - in the 7+ years I've been birding here, both on the same day. We've had a few more than those two, but not many. It follows that we'll occasionally be getting younger birds too. My questions are these:
    1. Where argentatus is actually a rare bird, would a 1st-winter be unequivocally identifiable?
    2. What about a 2nd-winter?
    3. Does anyone know of an ID paper out there somewhere, addressing this very issue?

    As I sift through the myriad argenteus HGs on the Axe estuary, hoping for some thrills, I cannot help noticing the enormous variability in the youngsters, and have come to the reluctant conclusion that pulling out a 1st-winter argentatus would be impossible. Am I wrong?
    Not Quite Scilly...

    Devon Bird News

  • #2
    Gavin

    It is tough and it may well be that the myriad Herring Gulls include argentatus. Here we tend to look for large size, sometimes a broken tail band like GBbG, but the best method is illustrated by the attached image....

    Brian S
    Attached Files

    Comment


    • #3
      Like it!

      Cheers Brian. Based on the number of adults we get (very, very few!) I am assuming a similar ratio of young birds so, yes, no doubt the horde very occasionally has a 1st-winter argie or two tucked away. In the absence of a ring, will one of them ever be do-able to a level that leaves no room for doubt, as in Caspian Gull, say?
      Not Quite Scilly...

      Devon Bird News

      Comment


      • #4
        Try the Gull Research Organisation web pages.They have detailed descriptions of all European gulls and great photos to show you the birds.
        They are currently working on the website ,so not everything is available yet.Argentatus/argenteus is though.

        Comment


        • #5
          Originally posted by Pale Male View Post
          Try the Gull Research Organisation web pages.They have detailed descriptions of all European gulls and great photos to show you the birds.
          They are currently working on the website ,so not everything is available yet.Argentatus/argenteus is though.
          GR is great, but do they offer any insight into differentiating 1cy or 2cy argentatus from argenteus? When I read the pages for these ages, there are clearly no concrete ways for doing so; where I live, in Suffolk, I reckon that adults are more likely to be identified.

          Brian S
          Attached Files

          Comment


          • #6
            Originally posted by Pale Male View Post
            Try the Gull Research Organisation web pages.They have detailed descriptions of all European gulls and great photos to show you the birds.
            They are currently working on the website ,so not everything is available yet.Argentatus/argenteus is though.
            Thanks Pale Male but, as Brian says, GR doesn't really provide what's needed to separate the subspecies in 1st or 2nd-winter plumages. I also have Malling Olsen and Larsson and Duivenduk, but again I cannot see sufficient there to clinch an argentatus in 'vagrant' context vs argenteus.

            Surely this has been written up somewhere?
            Last edited by Gavin Haig; February 21st, 2012, 09:11 AM.
            Not Quite Scilly...

            Devon Bird News

            Comment


            • #7
              Originally posted by Gavin Haig View Post
              Thanks Pale Male but, as Brian says, GR doesn't really provide what's needed to separate the subspecies in 1st or 2nd-winter plumages. I also have Malling Olsen and Larsson and Duivenduk, but again I cannot see sufficient there to clinch an argentatus in 'vagrant' context vs argenteus.

              Surely this has been written up somewhere?
              There have been a couple of papers in Birding World which may hold some answers:

              Golley, M. , (1993), Identification of argentatus Herring Gull., Birding World, 6: 32 - 38.
              Chylarecki, P., K. Eigenhuis. , (1993), Identification of argentatus Herring Gull., Birding World, 6: 166 - 167.

              I can't find any reference to British Birds papers on argentatus, but I'm not at home so can't check fully - there may be something hidden away.

              Mark

              Comment


              • #8
                Gavin,

                this doesn't really help with id of immatures but it's interesting in terms of numbers and age classes etc

                http://www.kensor.net/Papers/scand1.html

                Argentatus are certainly scarcer down here on my patch of coastline than the study area above, but we usually have a few adults each winter, especially if there's an influx from the north or the continent. Best showing this year was the same day an Iceland turned up during the very cold snap. Young birds are much more guesswork for me and I look for (rightly or wrongly): broken tailbands, pinker legs, overall look vaguely reminiscent of GBBG, looking still quite juvenile-y etc. They seem to be so variable.

                F
                OBC John Peel Awesomeness
                The little things they make me so happy, all I want to do is live by the sea...

                Comment


                • #9
                  Thanks for references folks, much appreciated. I don't subscribe to BW, but should be able to get hold of the necessary volume ok.
                  Not Quite Scilly...

                  Devon Bird News

                  Comment


                  • #10
                    Its interesting that you need a full description for them.In Ayrshire our records committee and bird report don't include them as they couldn't care less about a common sub-species.
                    Mind you they rejected a common x mediterranean gull I described coz' they didn't know what one would look like??
                    Mr.Darwin your finches don't exist coz' we've never seen them before!!

                    Comment


                    • #11
                      Originally posted by Gavin Haig View Post
                      Thanks for references folks, much appreciated. I don't subscribe to BW, but should be able to get hold of the necessary volume ok.
                      Gavin - If you're struggling to get copies, drop me a line as I'll be able to send you scans of mine.

                      Got to admit, I don't pay as much attention to immature 'probable argentatus' as I should do. Adult argentatus can sometimes form up to 10% of adult Herrings present in the local harbour, so it follows that there should be a fair few 1st/2nd yrs too. There have been some rather impressive dark-backed argentatus recently, presumably coming from some distance away. I'm with forktail on thoughts on likely juvs - large and bulky, frosty and reminiscent of GGBG. Hard to nail down one or two diagnostic characters though.

                      Mark

                      Comment


                      • #12
                        As Mark has said we get a good proportion of dark-mantled adults that are relatively straightforward to pick out in the North East.
                        In relation to 1st-winters, once we get past Christmas it has always seemed to me that those individuals that fit both Mark and Forktail's description of large, bulky, frosty and ' looking still juvenile-y' ( I'd just add that for me that means those that have more retained juvenile scapulars) in combination with plainer tertial centres, with less pale notching were almost certainly argentatus.

                        Can 1st-winter argenteus ever show a combination of these features in late winter?
                        Alan Tilmouth

                        Comment


                        • #13
                          Originally posted by Mark Newsome View Post
                          Gavin - If you're struggling to get copies, drop me a line as I'll be able to send you scans of mine.
                          Very kind Mark , thanks, but I've lined up the loan of volume 6 this weekend. Looking forward to a thrilling evening by the fireside!

                          Originally posted by BirdNEast View Post
                          Can 1st-winter argenteus ever show a combination of these features in late winter?
                          That's a very good question Alan. I'll be having a closer look at our 1st-winters with that in mind. Watch out for a lot of photos of big brown birds appearing on NQS in the near future!

                          Thanks too for the ID pointers guys.

                          A thought for Pale Male...
                          The reason a full description is required in Devon is precisely because argentatus is not a common sub-species. Not down here anyway. The reference in forktail's post details a study carried out 1978-83, and, interestingly, one of the findings was that argentatus rarely penetrate to the W coast of Scotland. Has that changed in the ensuing 30 years? Mind you, if the Ayrshire Bird Report doesn't mention argentatus at all, how would anyone ever know?!
                          Not Quite Scilly...

                          Devon Bird News

                          Comment


                          • #14
                            Hi Gavin

                            years ago, when I lived near an inland refuse tip that pulled in hundreds of large gulls I tried to use every reference from Grant to Golley to ID argentatus. From memory a large %, perhaps most of the adults, were identified as argentatus. Around Xmas we often seemed to get an influx of real bruisers, often with white-wings in tow. I seem to remember reading some ringing study that showed argentatus leap-frogged coastal argenteus: Coulson??? could be wrong.

                            As others have said, we would claim '1st years' using the criteria already mentioned. I remember being gratified to read that Lars Jonsson sometimes couldn't decide if he was looking at a 1W GBB or a 1W argentatus; seemingly something we weren't allowed to admit (tho there's more info on moult, Malling-Olsen, internet etc since then).

                            But, I did find some of the stuff mentioned in the BW article (ace illustrations btw) didn't seem to work, even on adults - but then, eg, I didn't know there are dark-backed birds with argenteus wingtip patterns on the near continent. My problem now is there are no tips, so no gulls and it is all so easily forgotten. Let us know how you go on?

                            regards

                            Mick

                            Comment


                            • #15
                              Originally posted by mick cunningham View Post
                              ..... Around Xmas we often seemed to get an influx of real bruisers, often with white-wings in tow. I seem to remember reading some ringing study that showed argentatus leap-frogged coastal argenteus: Coulson??? could be wrong.

                              .....
                              regards

                              Mick
                              That a large percentage of Herring Gulls wintering in NE England and at inland sites such as in the London area involves argentatus has been confirmed by ringing studies. See for example: Stanley, P. et al. (1981), ‘The Origins of Herring Gulls wintering inland in South-East England’, Bird Study 28: 123-132 (http://www.tandfonline.com/doi/pdf/1...63658109476712) and Coulson, J.C. et al, (1984) ‘Scandinavian Herring Gulls wintering in Britain’, Ornis Scand 15: 79-88 (http://gull-research.org/papers/coulson01.html). The situation here in the West Midlands mirrors these studies, being an area where few Herring Gulls breed but there is a large influx of wintering birds. Morphological characters (e.g. percentage of adults with a full white tip to p10) and time of arrival and departure in Herring Gulls wintering in the West Midlands region match the studies referred to above.

                              P.S. For some useful photos of 1cy/2cy - but not much textual commentary - see:

                              http://cyberbirding.uib.no/gull/ind_hg.php

                              and

                              http://calidris.home.xs4all.nl/tatus4.htm


                              Alan
                              Last edited by ARD; February 23rd, 2012, 11:28 AM. Reason: Added URLs

                              Comment

                              Working...
                              X