L. michahellis: adult February

General description:

At the start of the calendar year, only very limited numbers of adult Yellow-legged Gulls spend the winter months as north as NW France. At the dumping site of Dannes, near Le Portel, large mixed flocks of mainly Herring Gulls (1,000's) from NW and N Europe can be found including adult Yellow-legged Gulls (few tens in January 2002). Other spots in NW France which hold numbers of adult Yellow-legged Gulls in other seasons, e.g. Etaples, Le Portel and Boulogne-sur-Mer only hold single birds in mid-winter. Scattered records in the Netherlands involve single birds along the coast at Westkapelle, Maasvlakte and IJmuiden. Inland records can be expected from dumping sites and along the rivers, mainly in the southeast along the Meuse. Numbers hardly exceed ten a day in this period of the year, although YLG aggregate on some spots with few tens. Numbers remain low in February, March, April and May, but increase after breeding. By June, over 700 Yellow-legged Gulls can be found at Dannes (year 2003).

Features of adult michahellis:

As can be expected, there is no surprising moult going on in adult birds, from January to April. The average adult michahellis finishes primary moult by the end of October. By January, the outer primaries may show slight wear already, maybe caused by their common habit to feed on dumping sites in NW Europe. The upper tertials and inner coverts may show wear as well, as they were moulted early September last year and are over four months of age already. The winter head streaking, which was obvious and concentrated on the ear-coverts, around the eye and up to the crown by September and October, has been worn away by mid winter, leaving the snow white appearance of adult michahellis as mentioned in many bird guides. Mid winter adult michahellis is the classical, "well-known" plumage of Yellow-legged Gull and in most birds, this plumage shows easy clues for identification:
- Snow-white head with sometimes remaining head streaking around the eye;
- Red orbital ring and clear yellow iris;
- Yellow bill, sometimes orangey-yellow, with the red gonydeal spot which slightly extends on the upper mandible and a clear, obvious gonydeal angle;
- In profile the head and neck are strong and powerful, michahellis is rather high breasted with long wing and long legs;
- Upper-parts grey tone normally ranks between 6 and 7 Kodak Grey, neutral grey. Michahellis lacks the blue tinge as can be found in argentatus;
- Michahellis shows relatively much black in the wingtip, normally with a complete black sub-terminal band on p5 of even broadness. Sometimes there is even an isolated black angular spot on the outer-web of p4, although this is normally absent in adults. The black patch on p10 is relatively broad at it's most narrow point, at the feather's edge of the inner-web. Here, at the feather's edge, the black patch is still as broad as or only slightly less broad than the white mirror on p10. In other words, the grey area of the inner-web is limited to the basal half of the visible primary in most birds. Nevertheless, the grey patch of the inner-web may run further down and, when combined with a broken sub-terminal band on p10, may resemble nominate Larus argentatus. Normally p10 has a complete sub-terminal band, but it may be broken at the centre, creating two isolated spots at the feather's edges. A broken sub-terminal band on p10 may occur more often in eastern populations than in West Mediterranean populations (according to e.g. Jonsson, Alula 3/98). Normally, p9 has a mirror as well, on the inner-web, not reaching the feather's edge on the outer-web;
- And of course, as the name suggests: deep yellow legs.

Moult of remiges and rectrices in June:

Adult michahellis start the complete moult on the breeding grounds, when feeding the pulli. By June, when the juveniles fledge, adults disperse and can be found along the coast of NW France. We don't have sufficient data on primary moult stage of adult michahellis in June, but normally the secondaries and rectrices are still old, and by the end of June, adult michahellis have shed P3 or P4. See e.g. this flying adult. However, moult can be more advanced and some adults have shed P6.

Timing and strategy of body & covert moult in June

As soon as P2 and P3 are dropped, most birds start to shed the outer median coverts, followed by the upper tertials and innermost greater coverts. Subsequently, the inner median coverts are dropped. This is the moult stage many adult michahellis show by the end of June. 
See the Topography Section for explanation of feather tracts.

Michahellis at Le Portel, NW France.

Le Portel doesn't hold a large colony of Yellow-legged Gulls in the near surrounding. Colour-ring and metal ring recoveries of birds in NW France and at Westkapelle (most in the period July - September) reveal that birds originate from southern France (the Mediterranean coast near Marseille), eastwards to northern Italy and from Croatia to Switzerland. Whether other populations are involved in NW France as well, still has to be found out. Future colour-ring projects may answer this question. At Le Portel, especially the male Yellow-legged Gulls from southern France can be identified readily easily as they are huge, powerful birds, in profile not unlike nominate Larus argentatus from Scandinavia. However, scanning through a flock of Yellow-legged Gulls, some birds may be appear small-billed, round-headed with a 'friendly' facial expression and consequently they may be much more difficult to identify. Yellow-legged Gull populations with the smallest measurements can be found on the Atlantic Islands. See also the website of Nick Rossiter.

By March, many adult Yellow-legged Gulls return to the breeding grounds. The breeding season starts early for this species which breeds in southern Europe compared to argenteus, graellsii and of course compared to intermedius and argentatus, Fledged juveniles which dispersed over 500 km already can be found at Le Portel in July.

Tables:

no tables.

Yellow-legged Gull (michahellis) adult, January 01 2011, Tel Aviv - University Garden, Israel. Picture: Amir Ben Dov.