North Spain (‘cantabricans’)

Mantle: much paler; in overcast daylight a rather pale grey with a blue/purple tinge, slightly darker than argenteus in south-west France but very much paler than graellsii and thought to be usually paler than Mediterranean Yellow-legged Gull. Dubois (1987) noted the pale mantle colour of cantabricans relative to michahellis. However, Teyssèdre (1983) thought that cantabricans had partial overlap with Mediterranean Yellow-legged Gull on its mantle colour with a tendency to be paler. The present study suggests that some overlap does occur although in general cantabricans is paler than Mediterranean Yellow-legged Gull. In poor light, however, as noted for Yellow-legged Gulls of other forms, the upperparts colour darkens to a disproportionate extent

Underwing: the trailing edge is pale grey, not dusky as in Mediterranean Yellow-legged Gull.

Size: smaller; close to graellsii. Dubois (1987) also reported on the smallness of the form, noting its size as sometimes even less than that of graellsii.

Structure: much slighter in all respects; similar to graellsii with its short legs, rather flat chest, small rounded head and a bill which is slender with a slight gonydeal angle and often slightly tapering with a pointed tip. The necks are thin enough to be almost snake-like in some individuals. The wing shape is similar to that of the central Canaries and therefore to argenteus. Dubois (1987) commented on its closeness to argenteus in general shape and emphasised its weak bill.

Bare parts: tendency to have an orange hue to the red gonydeal spots and orbital ring in August; the gonydeal spot was not extensive, being restricted in general to the lower mandible. However, Teyssèdre (1983) thought the orbital ring was red and Dubois (1987) that the gonydeal spot was large. Burger & Goedfeld (1996) state that, in north-west Spain, 5-10% of the Yellow-legged Gulls have pink or partially-pink legs and in the present study about 2% of the presumed Yellow-legged Gull adults showed completely pink legs. However, it has also been claimed that such pink-legged birds are actually subadults and that adults do always have yellow legs (Yésou, 1993).

Calls: very different; similar to argenteus in all respects as found by Teyssèdre (1983; 1984) and Dubois (1987).

Moult in adults: less advanced in August with about equal proportions having P1-P3 new, P4 missing, P5 growing, P6-P10 old and P1-P4 new, P5 missing, P6 growing and P7-P10 old. The heads were similar to those in the central Canaries, being sparsely marked with brown speckles on the crown, nape and forehead and denser speckling around the eyes. Teyssèdre (1983) thought that the heads became streaked by October but Dubois (1987) does not regard this as fully substantiated. Bermejo (1999), however, reports that there is streaking around the eyes, crown, neck and nape in winter which may persist until January or February.

First-years: often rustier-brown with 20% ruddy brown and 65% grey-brown with a ruddy tinge; they also tend to have a pale base to the bill. Dubois (1987) reported on the greater tendency for a pale window on the inner primaries in cantabricans than in Mediterranean Yellow-legged Gull and one juvenile did show an obvious pale window in the present study.

Moult in first-summers: in early August distinctly later with the most retarded growing P8 and missing P9, the most frequent growing P9 and missing P10 and only a minority having completed moult.

Second-years: In August, similar to forms from further south except that the primary moult is later (see above) and the legs are always flesh-coloured with no yellow or straw tinge. By February, from Newell's photographs (Newell 2001), apparently more retarded than the forms from further south with: a) flesh legs, b) less grey on the wings (in two of the three examples shown in flight, the wings are almost entirely brown-grey with the other one showing grey inner primaries and grey mottling on the lesser and median coverts), c) some brown feathers remaining in the scapulars and back although these are now mainly grey, and d) more extensive, more solid and darker subterminal tail band; in one case out of three, though, the tail band is beginning to break up. In all three cases the dark secondary bar and outer primaries are very obvious. The bill is pale from the base to about 70% of its length in two cases and quite retarded in another with only the basal area becoming pale. These observations are preliminary in view of the small sample sizes.

Moult in second-summers: in August the timing of primary moult is similar to that in adults with typically P4 or P5 growing and P5 or P6 missing.

Third-years: more pronounced brown markings with quite heavy mottling on the secondary bar and with an obvious carpal bar and dark markings on the primary coverts. The tail may show faint remnants of the subterminal band and the mantle is a less clean grey colour showing small areas of brown. The bill is usually a bright yellow but the legs can still retain a pinky tinge, giving a rather lurid yellow-pink effect.

Moult in third-summers: a more retarded moult with typical state of P4 or P5 growing and P5 or P6 missing in early August.

Information needed: larger samples for wing features (first-years); all features (older immatures), middle primaries (adults).

Comment: The most detailed account of Atlantic Iberian Yellow-legged Gulls is by Bermejo (1999). He describes adults as slightly darker than Mediterranean Yellow-legged Gull with a large mirror on P10, possibly a small mirror on P9, a red gonydeal spot and an orange-red orbital ring. Based in Galicia he seems to describe a form, appropriately enough, inbetween those of south-west Portugal and Cantabria with the dark mantle shade, small P9 mirror and red gonydeal spot being found in the Portuguese form and the orange-red orbital ring in the Cantabrican form. For first-years the grey-brown mantle colour with ginger tips to the coverts is typical of Portugal and the black bill with pale base is typical of Cantabria.

In another study, in northern Spain at Ondarroa in the Basque country close to San Sebastian, Dick Newell (Reid, 2000) says that: "relative to michahellis in the Mediterranean, Cantabrican Gull is, on average, 'cuter', slimmer, shorter legged and possibly slightly paler. Relative to argenteus it has a long rear attenuation, bright yellow legs, red eye-ring, is possibly slightly darker and has a similar wing-tip pattern to michahellis. Relative to graellsii and intermedius (direct comparisons), usually slightly larger". Compared to the birds at Santander, the birds further east appear to have a more marked attenuation but are otherwise quite similar. In particular the data obtained from an analysis of the photographs placed on the above web page (shown in the statistical tables in Appendix I) confirms the characteristic features of adults and first-years suggested by the Santander studies and also shows that first-winter birds tend to have dull tails and only one-bar on the inner wing. The orbital ring appeared to be a dark orange in adults from the photographs but this may not be a true reflection of the actual colour. The gonydeal spot is large and red but is more diffuse than on the Dark Atlantic Yellow-legged Gulls.