It is always a mistake to visit Dennis Point Wharf, Lower West Pubnico when the gulls are in, because you always come away more confused than when you arrived. Yes this post is all gulls, so, I won’t be offended if you wander off now, gulls do that to people. I invite comments from those who make it too the end, provided the word ‘certifiable’ in not a part of those comments
Unlike many silly ideas, evolution is real and provable and, after an undefined period of time but certainly in excess of 6000 years, evolution will result in one thing becoming many and so it continues. The one thing under discussion here is the gull, of which there are variously 55-62 species, I say variously because the taxonomy of gulls is in a state of flux, as demonstrated by the ‘discovery’ of the Caspian Gull in Europe in the 1980s. Of course Caspian Gulls had known that they existed long before enterprising dump watchers figured them out and had no truck with that Herring Gull lot, it is a good example of why gull taxonomy should be written in pencil.
Using the International Ornithological Congress’s taxonomy we have (currently) 55 species, world-wide. At least 28 of them have been recorded in North America. Nova Scotia has managed 20 or perhaps 22. We are not talking a big family range here but for sheer complexity, they knock many other groups for six (a Cricket term). The gull we search for in southern Nova Scotia in winter is Thayer’s. Actually we also yearn for Yellow-legged, Ivory, Ross’s, Slaty-backed, Black-tailed, Kelp (now!) and even (another) Caspian. But they are all easy, Thayer’s isn’t and I don’t mean easy in terms of say wood warblers in breeding plumage, more that the ID of the yearned for birds are more straightforward, Thayer’s is not and no amount of literature makes it any easier because, the definitive field marks are not fully established away from their core wintering areas, hell we can’t even agree that we get nominate Iceland Gull here (we surely do), let alone a version of Thayer’s that sits somewhere nearer the beginning of basic species divergence than the end, probably.
So, we have three versions of a white-winged gull although two don’t have white-wings, see, we are in murky waters already and we haven’t even examined a feather, let alone a complete bird. We can simplify things though. Iceland Gulls Larus glaucoides (you’d think that meant Glaucous Gull in relict or latin or whatever it is but no!!!) have white wings at all ages (biscuit-coloured is a degree of white) with no shading or shadow image or dark markings on the primaries, just white. They are not common here and are from the Old World, now just ignore Iceland Gull, not relevant.
Kumlien’s Gulls are the same in general structure as Iceland Gull except that they have grey shading on the primaries, perhaps in 50 shades but I’m not going to beat myself up over it. The primary pattern can vary to such a degree that there is no defined pattern for Kumlien’s Gulls but a range, however, some patterns are more regular than others. More important is the shade of the primaries, the blacker it is, the less likely it is to be a Kumlien’s (sometimes). Kumlien’s Gull is a common winter bird in NS, go where there are gatherings of gulls in winter and you should be able to find one or ten.
Thayer’s Gull is a primarily western species (probably), or at least that is where the core population winters. It has a very dark grey to blackish pattern on the primaries that is more specific to the species within a narrow range than is the wing pattern on Kumlien’s. There is some variation but the pattern, to be Thayer’s, has to conform to within known variations. Thayer’s Gull also occurs regularly around the Great Lakes in winter and it might, at this point, be fair to suggest that there are distinct eastern and western wintering populations (as a generalisation) and that ‘our’ scant few in Atlantic Canada are more likely to emanate from the Great Lakes than the west because it is nearer and logical, if only the birds knew that.
So what on earth do we keep seeing here in Atlantic Canada that isn’t a Thayer’s doesn’t look like a Kumlien’s and bears no relation to Iceland?
This bird was at Dennis Point Wharf on December 30th. It has a pale iris, only a smallish percentage of western Thayer’s have a pale iris, maybe 20-30% (I have read that more northerly wintering birds have a higher percentage of pale-eyed birds, subjectively), but what if the eastern Thayer’s actually have a higher percentage? And how will we ever know if we lump Thayer’s, as is expected reducing variations to something many will only glance at because they don’t ‘count’, and we won’t then document, record, comment extensively on, learn, understand and appreciate.
This bird also had a darker mantle than the Kumlien’s, you can see that, we could see it easily in the field in fact it was so distinctive that, when the gulls did their panic and shuffle thing, you could find it in bins with a single scan just based on back colour, and that would be a scan of quite a few gulls just sat on the water awaiting the next fishy bit sluiced out of the fish plant pipes (and long may that practice continue, the pipes that is).
The primaries are dark enough for a Thayer’s, fact, and I don’t think there is an argument there. The pattern too is good for Thayer’s (mostly), except that many stand-out Thayer’s have a sub-terminal mark on p5. The primaries are counted from the outside in, so ten is outermost. A mark on p5 is not diagnostic of Thayer’s but certainly helps, had this bird got one it would be entered in ink now. Now look at p6, it is marked with a broken band. Out of 60 adult Thayer’s examined by gull experts, 10% had a broken band, (not sure whether the data notes whether p5 was banded too on these birds). One of the gull experts, a man whose opinion all who watch gulls respect, stated that this bird was “at the least-marked end of the Thayer’s Spectrum” ergo it is at the most marked end of the Kumlien’s.
If we find this gull to be extreme with some aspects, enough aspects in fact, that lean towards Thayer’s, it is a Thayer’s. If we keep propagating such a broad range between Thayer’s (least marked end) and Kumlien’s (most marked end), then we will never progress. I think the line is too vague and would welcome more latitude. I think the darkness of the primaries, as in this bird, is enough to call it an ‘eastern’ Thayer’s Gull with the mantle colour, general structure and primary pattern tempered by the missing strap on p5 and broken strap on p6. For now I think we need to err on the side of Thayer’s, of only to encourage more people to document, photographically all possible records.
So what am I saying? Alix and I saw an adult gull at Dennis Point Wharf. It was with lots of other gulls, most of which we could identify to a species. Using the known criteria as currently applied to Thayer’s Gull, one of the individuals had a claim to be a candidate but, the primary pattern was not 100% Thayer’s, more in the region of 30-40% given the lack of a strap on p5 and the broken strap on p6 but offset by the Thayer’s colour and the acceptable p10-p7 patterns. The mantle was Thayer’s, the pale eye was variously found in 20-30% of Thayer’s. Nothing about the gull really suggested Kumlien’s. In applying the distinctiveness test, i.e., can you re-find the odd bird repeatedly? The answer was yes, so our bird was visually different, now was it a Thayer’s form?, perhaps, is the best I can do.
And just to confuse, this one was at Dennis Point too, no wing shots unfortunately.
Here are a couple of links to Thayer’s chat with some nice photos to enjoy, the rest willl confuse you.
Then go and read this: http://www.anythinglarus.com/ Amar knows his gulls and any statement from him carries weight in the gulling community, but it is still just one opinion.
Then consider a world where there are three gulls, all obviously closely related but many of them identifiable in the field. For the ones we can identify, we call them Iceland Gull, Kumlien’s Gull and Thayer’s Gull. For those we cannot we call them… But the point is, we put aside the tidy filing mentality and just get on with it.
I have no authority regarding anything except what perceive. I have seen a lot of gulls, I’ll see a lot more before they turn on the toaster and I will try to identify and file everything I see. For now, and until the next Caspian Gull event happens (a multi-split within American Herring Gull?), I have seen the following, * = currently a sub-species using Malling-Olsen and Larsson.
Russian Common Gull*
Great Black-backed Gull
European Herring Gull
American Herring Gull
Lesser Black-backed Gull
Common Black-headed Gull
And not real species:
Great Lakes Gull
And if you think the Iceland gull group is confusing, how many species on this Indian beach?
IF I am talking out of my ass please say so and I’ll wear thicker trousers.