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