Candidate Heuglin's Gull L heuglini
1-2: © Ronald van Dijk, 25-06-06; 3-4: © Ruud Altenburg, 25-06-06; 5: © Ruud Altenburg, 23-07-06; 6: © Mars Muusse, 23-07-06. Amsterdam, Netherlands.
Compared to the previous candidates, this bird is yet again more advanced. At the end of June, it had replaced the tail, all secondaries and all but the outer two primaries. Such a moult scheme suits Baltic Gull best, but the shade of grey of the adult-like scapulars and fresher two greater coverts is too pale for fuscus; compare to the 2cy graellsii/intermedius Lesser Black-backed Gull in 4 (the other birds in the pictures are various age classes of Lesser Black-backed Gull and, in 5, a 1cy Yellow-legged Gull). There are some records of birds ringed as pullus in Finland that at a later age showed a much paler than average mantle (e.g. white CYHP), but all of such birds observed so far were on the slower end of the spectrum rather than the more advanced. One month later, it appears to show "Staffelmauser": the outer primaries are growing and P1-2 have been dropped. For more pictures and information about this bird, please see Ruud Altenburg's site.
Is this an extremely pale fuscus, an exceptionally advanced intermedius or an advanced heuglini? The new inner primaries are not pale grey, but this bird from Russia demonstrates that not all 2cy Heuglin's Gulls show pale grey second generation inner primaries. If you have photographs of a ringed 2cy Lesser Black-backed Gull similar to this bird, please contact the authors.