The Meissner ranking scale
White reaching rhachis on inner primaries is a Sanderling feature, but it's typical of eastern Dunlin populations as well. In The Handbook of British Birds. Vol. IV, H. F. Witherby (1958) remarks: Dr C. B. Ticehurst mentioned two large birds taken in Fair Is. on Sept. 23, 1905, which he considered to be C. a. sakhalina. I have examined these: female wing 116, bill 40, male wing 119, bill 35. The bills are certainly very large, but the wing of the female is short for sakhalina, and in both birds there is only slight edging of white on the outer webs of the inner primaries instead of the white extending to the rhachis as is usual in sakhalina. Among other large British-taken birds, I have examined only three with a considerable amount of white on the outer webs of the inner primaries (...) In the last the white just reaches the rhachis and in the other two not quite. These may be referable to C. a. sakhalina, but before admitting that race to the list I think we should have more definite evidence, as very occasionally examples of C. a. alpina have an unusual amount of white on inner primaries. (Compare this rather meagre material with figs. 2 and 3 below!) Engelmoor & Roselaar 1998, referring to Horvath & Keve 1956, attempted to use this criterion as well, but they were led astray by the Anglo-Saxon, irregular notation "P7" (= P4) in Greenwood 1986 and got no conclusive results (this notation is no longer used in Ginn & Melville 1983).
Here is at least a straw, hinting at a possibility, other than biometrical, to attack the question of Dunlin provenience. In a letter from 16.4.95, where he described working routines of the Polish catching stations at the mouths of Vistula and Reva, Wlodek Meissner made the following remark: ...we had collected data about the extent of white colour on inner (3. and 4.) primaries. We use this table to code the extent of white on outer vane of both primaries... and he adds at last ...birds with codes 3,3 or 3,2 could be from the far east. Below is the scale he was referring to in two states; first table form, followed by close pictures of the two outermost secondaries and the four innermost primaries:
Scoring scale for white on inner primaries of Dunlin, suggested by W. Meissner
| Extension of white | Score |
|---|
distance between white and rachis
longer than 1/4 of width of outer vane | 0 |
white colour doesn't touch rachis:
but a distance between white and rachis is
shorter than 1/4 of width of outer vane | 1 |
white colour touches rachis:
width of line of contact very short,
shorter than width of rachis | 2 |
white colour touches rachis:
width of line of contact longer
than width of rachis | 3 |
Fig. 1. Rankings 0 - 3 according to the Meissner scale.
Comment I: Colour, general appearance The pictures are a trifle better than nature; in some cases the white of primaries is more hidden underneath coverts; it may be necessary to lift these or gently brush them aside. The limits between white and grey are often diffuse when regarded at close quarters; small islets of brownish black occur in the white areas. In reality the grey colour of remiges and primary coverts is darker, almost blackish. Note that the crucial pattern - in my own version of the scale deciding the ranking - may occur in one out of four feathers only. Ranking 0 is by far the most common in the Baltic, it is typical of schinzii and western alpina birds.
Comment II: Primary coverts Only part of the primary coverts is seen here, these feathers are surprisingly long and stiff (not exactly matching primaries and supporting in flight when a primary is absent) and easily mistaken for just emerging primaries when in pin. The PC:s shown in rankings 0 - 2 are of adult type, with a step between the white end-spot of inner and outer webs. (This pattern will occur in some juveniles as well, but in those cases more blotchy, diffuse; in an overwhelming majority of cases a western alpina juvenile has just a thin "nail" to primary coverts). In ranking 3 the bird has instead been equipped with "droplet primary coverts", which often occur here together with "adult buff" medians; one spot is of conical form, one of hybrid character and one elliptic - normally a bird has conical or elliptic + hybrid, but not all three.
Comment III: Provenience In my opinion the "droplet" character emerges in the eastern part of the grey median area and then follows the "adult buff" character eastwards with increasing frequency. This is little more than a guess, but I have a strong feeling, based also on what I have seen of the extent of red and yellow on scapulars, that ranking 3 + droplet coverts + "adult buff" medians (in most cases also: P1 -3(4) full-grown in the Baltic on July 15th, P1-5 full-grown from July 20th) always implies more easterly origin (or type) than Yamal Peninsula; Gydan Peninsula or even Taimyr.
Fig. 2. Mid-September 2005 saw an unusually rich influx of large-sized juvenile Dunlin on the Falsterbo peninsula, the size and general appearance of which wouldn't have raised an eyebrow in Japan; they seem to arrive in the company of assumed Nearctic Knots. The picture - although it didn't come off well technically, the camera was too close to the motive, couldn't cope with that much reflexion - gives an impression of the white wing-patch in a bird where white reaches rhachis in four primaries along half of their visible extension, and over some distance in P1 as well. Note the very thin white nail to primary coverts in a juvenile, the one in Fig. 3 is broader. The visible median coverts are edged sepia and white with dark centres, the most common pattern in unmoulted juveniles (these medians are of poor quality and very worn; in the sequence of populations visiting the Öresund area birds with unmoulted or growing median coverts are seen till c15 November. I am not even sure that all populations moult their medians, many birds have very worn - and maybe bleached 1st generation? - medians in December - January. ADDITION: Eight juveniles on 17.11.05 had unmoulted wing coverts, only scapular coverts at each side of the back fresh. These birds were rather retarded in their development, I wonder how much more - if anything - they can exchange before New Year. Cf. a pacifica wing from the Puget Sound collection, note "droplet" primary coverts. Höllviken 17.9.05. [CP]
Fig. 3. A juvenile with ranking 3 in P2 - 4, note the narrow black edge next to rhachis in P5. This bird has moulted median coverts, and is close to completing its winter plumage, a few rows of 1st generation small coverts remain. The pale buff edges to medians in my opinion assign it to the Siberian area with "adult buff" median coverts, and the type of ranking 3 shown in the picture is the same met with in the summer migration as well. (Adult buffs are the earliest adult moulters in Dunlin, and i am fairly sure that juveniles from the same areas are the first ones to complete their winter plumage as well). The wintering population in the Baltic tends to more pale white and grey, lacks these buff edges in winter, but i am not sure if wear is involved; coverts must be studied throughout their "history", and this is very difficult in the case of the ever-moving Dunlin. The very distinct shaft-streaks of medians may be diagnostic, the most pronounced category of adult buffs has them. Höllviken 20.9.05. [CP]
Back in 1995 I had little experience of Dunlin morphology and was happy to take over a ready-cooked ranking scale, but I soon discovered, that the white "primary-patch" had no fixed position, it could embrace any combination of the four (or five) innermost primaries, so I ranked primaries 1 - 4 from the outset, giving the highest value of any of these four primaries as the ranking of the individual bird. Since then, I have ranked more than 2,500 birds according to this scale. Interesting results, probably exceeding even Meissner's wildest expectations, can be seen in Figs. 14, 15, 16 and 17 of Phenology and biometry of Dunlin Calidris alpina migrating by way of the Sound area, S. Sweden. and in Fig. 1 of Migration progress of juvenile and adult Dunlin.... [CP]
Text additions 25.9.05, figures revised 21.9.05, links corrected 10.2.07.
To "Studies of migrating Dunlin Calidris alpina in the Sound area, S. Sweden: Introduction"
To "Phenology and biometry of Dunlin Calidris alpina migrating by way of the Sound area, S. Sweden"
To "Migrating Dunlin Calidris alpina in the Baltic area: the moult issue"
To "Risk-prone or risk-averse? Dunlin Calidris alpina migrating with and without moult-gaps in the Baltic area"
To "Wintering and spring staging Dunlin Calidris alpina in the south Baltic area"
To "Migratory progress of juvenile and adult Dunlin Calidris alpina from two perspectives: the Baltic and the Waddensea"
To "Bill-length distributions in Dunlin Calidris alpina"
To the bill length account
About "adult buff" coverts
To the Dunlin literature list A - J
To the Dunlin literature list K - Z
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