The Bridlington Bay Gull
I have had a chance to review some work I did on these a few years ago *. This was based on literature search, examination of specimens from Greenland (Tring) and observation of Iceland and Kumlien’s Gulls in Britain, Ireland, Iceland and Newfoundland. Criteria were suggested for identifying out-of-range juvenile/1st winter Kumlien’s Gulls.
I have also received some illuminating correspondence following this post. The upshot is that the most parsimonious explanation for the appearance of this 1st winter bird is that it is a Kumlien’s Gull. There are more obvious examples, so it’s reasonable to exercise caution. Calling it glaucoides/kumlieni thus indicating (in UK context) an interesting and unusual bird is reasonable. Calling it ‘just an Iceland Gull’, inferring that it is a standard/pure nominate glaucoides seems not to be defensible.
When I first saw the bird at Bridlington it was reasonably close. I could see straight away that it was an Iceland Gull. Lifting bins I was somewhat taken aback to see (what I would call) a Kumlien’s type pattern on the primaries. Despite having seeing annually 10′s of Iceland Gulls over 5 years in Ireland including small flocks of juv./1st winter birds, I only saw this pattern maybe 2-3 times.
“So how do you identify a juvenile/ 1st winter Kumlien’s Gull?”
Criteria (with photos) written up in Birding World in 2000 * still, I think, hold up quite well. I am sure these will be rightly questioned and improved with current ongoing study but it’s reasonable starting point:
“an outer primary pattern that we believe constitutes an identifiable vagrant first-winter kumlieni (on current knowledge) is of a variable brown wash centred on the primary shaft, spreading onto both webs and extending almost to the feather tips. It is most commonly plain, not ‘mealy’ or spotted, although many show a small subapical mark. From February to April, the brown wash and subapical marks (if any present) fade or disappear on many individuals, leaving the outer primaries a rather plain creamy-brown or off-white thereby increasing the number of kumlieni that may be inseparable from glaucoides. Other tendencies- and the are only tendencies- of first winter Kumlien’s include a shorter primary projection, an earlier moult for some mantle and upper scapular feathers (sometimes from Oct/Nov) a darker bill in mid-winter, a more distinct [plain] tail band and more contrast between the outer (darker) and inner (paler) primaries in flight on the more distinct individuals”
Peter Kristensen got in touch from Denmark. He helpfully asked the question the other way round.
“How do you identify a pure Iceland Gull (nominate glaucoides)?”
Saw your post about an Iceland Gull. I just want to let you know, that we last winter made an article on the subject in Danish, but what we did was to find all material on birds we knew for sure was pure Iceland Gulls [nominate glaucoides]. This means lots of gulls seen in Northern Europe and Greenland but also the big collection from zoological museum in Copenhagen – this includes many hundreds and some date back to the middle of the 1800. What we wanted to find out is, how much variation is there in Iceland Gulls – especially 2nd and 3rd winter. I had the feeling, that places like Iceland and sometimes the Faroes are difficult places to be absolutely certain that a dark bird is really a pure Iceland, and I therefore disqualified such a bird in order to document how much variation there is in 2 and 3 winter Iceland Gulls. What we found out is, that there wasn’t any variation amoungst the many birds collected in Greenland – they were all perfect whitish looking Iceland gulls.
So we turned the way of documentation around, and said – how can you identify a pure Iceland Gull (as we think this is more interesting than the many hybrids/kumlieni). So, if your bird was a rare bird that needed acceptance from a rarity committee I don’t think it would pass as a pure Iceland Gull – it is outside the variation we could find in our collections – not a lot but enough I think.
Peter H. Kristensen”
juvenile/ 1st w Kumlien’s Gull, Connecticut, USA, March by Julian Hough. A pale bird with similar if slightly less well-marked/more faded primary pattern to the Bridlington bird. Of course knowing where every Iceland type Gull comes from in NE USA is uncertain. While there is the bewildering variation, all the birds in Julian’s area pass as kumlieni. Julian comments “I would definitely be thinking of kumlieni for your bird since it would pass for that race over here in the US…I couldn’t get it passed as a dark glaucoides”
Phone a friend
I asked some friends with plenty of experience and interest in the subject, for their impression of the Bridlington bird, based on my photos:
Chris Gibbins (studied bird’s in Newfoundland) “Wow…actually this is a great great bird. More Kumlien’s like than I imagined! [from my verbal description]. Leave it with me to work on properly…”
Anthony McGeehan (studied birds in Newfoundland)
“Your bird could fit either ‘taxon’. I mean in structure: it could be a ‘Pretty Boy’ Kumlien’s. But what about plumage? There is a fairly heavy pigmentation on its chequered tracts – enough to push the limits for Iceland? But I don’t feel safe on that ground, given the variation within Iceland. For me, the crunch is the patterning on the primaries. On even a well-patterned Iceland (some have a soft pattern, just like Glaucous) the strength of the pattern seems to have an upper limit. That upper limit consists of (low contrast, of course) a pale rim on the primaries with a little ‘diamond’ of dark nestling at the apex of the subterminal rim (on its inner edge). I’m sure you know what I mean. You could describe it as an ‘anchor mark lite’. Anything more than that puts the bird into Kumlien’s territory. Obviously I could be wrong and there may be a tad more dark patterning that occurs in ‘extreme’ Iceland? I think the last sentence is speculation. So, on your bird, given the ‘excessive’ dark patterning that goes beyond my own limit, I’d be calling it Kumlien’s.”
Ian Lewington would have been very pleased to find it! Felt different to annual juv. Iceland Gulls in Oxford and almost all juvenile Iceland Gulls seen over several years in the west of Ireland, where most looked of a ‘type’ with all white wing tips. Verdict: most likely a Kumlien’s.
*Garner, M., Kolbeinsson, Y. & Mactavish, B. 2000. Identification of first-winter Kumlien’s Gull and the ‘Whitby Gull’. Birding World 13(3): 116-119