Both birds showed the stereotypical smith "look"; unusually smooth, dark underparts and hind-neck "shawl", relatively dark coverts and scapulars contrasting with pale head, pale new scapulars, and- although the most over-rated/least useful characteristic- pale based "Glaucous-like" bill (see fig 6 and sketch of ind.2). These features should only serve to attract attention before looking for the key identification criteria- tail pattern, upper- and under-tail coverts. All of this is covered by the excellent paper first published in Dutch Birding by Pat Lonergan and Killian Mullarney and this is well worth downloading from the Gull Research Organisation website (which also carries additional photographs).
|2nd w. Larus sp. (possibly smithsonianus) Cowloe, Sennen Cove, Cornwall 31/1/2011. As well as the features visible here this individual had typical smithsonianus under-tail coverts, but the spread tail and upper-tail coverts were not noted (see discussion below) before the bird disappeared. A perfect smithsonianus at face-value , but un-confirmed!|
My field experience of smith is limited to one week in California 15 years ago, so I will welcome comments from anyone out there with more field-time (though I'd consider anything less than a year inadequate!), but I have devoted most of my winter-birding for the last 20 years looking for them in this country. I have found 4 accepted 1st winter birds so far, seen two more in Cornwall, found an adult and 4th winter type I am happy with (though did not submit), but until finding a 2nd w.bird at Ditchford, Northants in December 2013 I went through a 5 year drought (not including the Sennen individual above) and had never seen a bird of this age I was happy with in this country. So now I have seen Mush's Jericho bird the two Hayle 2nd winters would seem to be a bit of a glut, and I am far from happy with it! However, I have lived amongst breeding argenteus since the '90s and have obsessively grilled them ever since so I hope the following discussion has some use.
As previously mentioned "ind.1"'s tail was it's worst feature; classic 2nd w. smith should have a "wrap-around" almost completely dark (blackish when fresh) tail and those outside the range of variation in argenteus show no white on the outer web of r6. Any white is usually confined to fine peppering at the bases of the outer webs of the outer 1-3 ff, distal fringes (fresh), and some shaft-streaks- again only in the basal half. It is not uncommon (?) for the outermost ff to have a complete white fringe, broadest at the base, and usually peppered blackish. From above there should be no white showing at the bases of the inner-webs as the ff need to be unnaturally widely spread to expose this and the upper-tail cov.s hide their bases, but from below the pale inner webs of the outer ff can be obvious. Unfortunately gents routinely show broader dark tail bands in 2nd w. than is typical of 1st years, and- not too rarely- can be even darker than ind.1 at least (see below).
|"ind.1" Hayle, 2/2/2015|
|"Ind.2" Hayle, 28/3/2015. As can be seen from the sentiment, this bird also showed a disappointing tail-pattern, and that I can't count as I have clearly shown pale slivers at the base of r4-6. Even so this pattern is marginally better than ind.1's!|
Although my photo.s are pixelated (thanks to the distances at the Hayle forcing the "stacking " of converters!) the outermost tail f. (r6) of ind.1 is mostly white with a sub-terminal band and black spotting on the inner-web. Although I have never seen it myself, and have no idea of the frequency smiths can show this, there are images in another excellent paper by Andreas Bucheim in Limicola (sorry there are no propoer ref.s here - I have lent both publications and still await their return, but I will cite them properly later) of birds with similar r6. Ind.2 appeared to have a slightly better tail, but the only view I had was during a brief period of preening before the bird took off so it could possibly have been worse! In either case the tail is not enough to settle their identification- though smith is looking second best so far!
Upper and under-tail coverts
Again smith should be much more heavily/densely barred dark in these tracts than in argentatus or argenteus, but although this is a reliable feature in 1st years moult in 2nd years can produce ff showing patterns from reduced barring to pure white. This seems to be more common in the upper-tail coverts, but I do not know if the "paler" ff are 2nd generation- i.e. produced in the bird's first complete moult to 2nd w.("2nd basic"), or isolated 3rd gen. ff replaced as part of a suspended pre-"breeding"("pre-alternate") moult .The latter is almost certainly the case in late winter (Feb./March), but because smith are relatively late/high latitude breeders this is probably rarer in early winter(?). Whatever the case any typical, or at least distinct smith upper-tail coverts (the longest ff over-laying the bases of the tail ff) should be more than 50% dark, and show at least 4 dark bars which reach the outer edges of the ff. There are many variations and it is common for the barring to be narrower or fainter basally which can be revealed when ff from the "2nd row" are displaced or missing. Feathers with dark centres or intricate patterns reminiscent of "white-winged "gulls are shown by more distinctive smiths and- although one should never say "never" in regards to any aspect of LWHG identification- possibly never shown by (pure) European Herring gulls- but see below!
|2nd w, L.a.argenteus, Sennen, Cornwall, 26/1/2011. Tail pattern better than ind.1 apart from more extensive pale flecking, but sparsely barred upper-tail coverts typical argenteus, and upper-rump/ back mostly grey.|
In their under-tail coverts at least the two Hayle individuals are far closer to smith and if Lonergan and Mullarney are correct then this feature alone could clinch their identification. Both birds showed a varying suite of supportive features so this seems reasonable but the problem is most of these can be shown to some degree by European birds, and until more is known about the significance of the "pale" outermost tail ff and dark under-tail coverts as anti- and pro-smithsonianus criteria respectively doubts will remain.