3cy michahellis in October
have plain grey upper-parts and coverts, although the outer lesser
coverts and some of the greater coverts show a barred pattern in
many cases. The lower tertials may be dark centred. The complete
moult in the under-parts and head has been finished. Birds show much
streaking on the crown, nape and ear-coverts. It takes about seven
to eight weeks to reduce streaking and by mid-winter (January) many michahellis
show clean snowy white heads.
The bare parts are typically less bright coloured than last summer
or as in adults, now showing a brown-red orbital ring, often a dark
hue in the iris, much black on the bill and still straw-yellow legs.
However, as can be seen in the images, the legs appear clear yellow
in some birds and some birds have very limited black on the bill,
e.g. only a diffuse streak near the tip on the gonydeal angle. It's
hard to exclude 4cy birds in these cases. An example of the average
September 3cy michahellis can be found in the first
image, photographed on October 01 2001.
The table below shows the average primary moult score for 3cy michahellis
in October: about 9.0 at the start of the month and P10 fully grown
at the end of the month.
For details on differences between michahellis and cachinnans,
see e.g. the article by R. Klein &
D. Gruber in Limicola, April 1997.
stage and pace of remiges and rectrices:
The complete moult started mid-May,
when 3cy birds dropped the innermost primary P1. By early July, the
average score had increased strongly: only P7-P10 are still old
second generation and the inner primaries are new. The score for
late-September averaged 9.2 in NW France.
As in adults, the gap between full-grown primaries and remaining old
primaries is about three feathers in general, or slightly more as
the table in the July section
shows. This large moult gap is typical for michahellis, and
not found in e.g. Dutch argenteus.
By October, the most obvious moult is in progress takes place in the
primaries. At the start of the month, the average moult score show
the ninth primary P9 fully-grown, at the end of the month the
average is near P10.
By the time P4 is fully grown, 2cy
birds normally start the complete moult in secondaries and rectrices.
The ordinary moult strategy in 3cy birds may be slightly later
(starting when P5 is fully grown, i.e. primary moult score 30).
Secondary moult starts in early August. The images on the July
page showing birds with open wings illustrate that all outer
secondaries are still present. By early August, the outermost
secondaries (S1 & S2, at the division between secondaries and
primaries) are normally dropped individually, but the central
secondaries are shed almost as in small groups, creating large gaps
of missing secondaries, nicely illustrated by this flying 2cy
bird and this stretching 3cy
The secondary moult finishes with the replacement of the inner
secondaries (about S17-S18), close to the tertials (which in fact
are secondaries as well). The completion of the secondary moult
coexists with moment that P8 is fully-grown. This is late-September
or early October in most individuals.
So, the secondary moult is
completed in most birds in the first week of October ( finished
approximately at moult score 45, about the time P8 is fully grown).
An example of an October 3cy bird still showing old secondaries can
be found in image 6733.
The findings in NW France are exactly in line with the findings of
Agnar Ingolfsson, who conducted research on Great
Black-backed Gulls (L. marinus) and Glaucous
Gulls (L. hyperboreus), published in Ibis 112, 1970.
The first secondaries to be dropped are the innermost six (what we
call tertials), followed (at moult score 25-30) by the rapidly
dropping of the outermost secondaries S1 to S15. The two waves meet
at S16-S17. In the first week of October, abraded old second
generation secondaries can be found in this place: S16-S17, but only
in a few birds. The low primary moult score are indicative for (may
correlate with) the moult score in the secondaries.
By the first week of October,
ordinary 3cy birds have completed the moult in the tail-feathers.
The common sequence has been a centrifugal moult: starting with the
inner tail-feathers and continuing symmetrically outwards to both
outer feathers. This tail-feather moult is completed by September.
New feathers are white with various amount of black markings. Some
individuals have a clean white tail. The new feathers can be
recognised by the fresh fringes and tips.
moult vs. partial moult
In the complete moult during the
summer, 3cy michahellis moult all the scapulars,
wing-coverts, tertials and flight-feathers. The complete moult
started in May, when P1 was dropped and the complete moult will be
finished when P10 will been replaced in October. By August, the
complete moult in the wing-coverts is finished with replacement of
the last central greater coverts and finally the feathers in the
carpal edge (outer lesser coverts). As those last lesser
coverts are replaced, 3cy michahellis start the
partial autumn moult. In this partial moult some wing-coverts and
tertials are included. It starts again with the upper tertials and
outer median coverts and is nicely illustrated by this
individual from October 01 moulting P8. The
outer median coverts are clearly missing.
3cy michahellis show a much larger individual variation in
moult stage than 2cy birds. (For instance: the same individual from
October 01 with P7 fully-grown, while the average score for
late-September is 9.2). So its hard to generalize on partial moult
stage in 3cy in September, and it may be strongly related to the
primary moult stage of an individual.
However, partial moult may start by the last week of August in
advanced birds. By late-September, the innermost greater,
median and lower lesser coverts and the upper tertials have been
replaced in the partial moult. The new coverts are adult-like plain
grey. The older coverts, moulted in the complete moult last summer,
may still show a diffuse barred pattern. Hence, the new median
coverts and upper tertials normally look much more adult-like and
fresher than the outer greater coverts and coverts in the carpal
The partial moult in 2cy michahellis
is often more obvious and explained in the 2cy
michahellis section. See Topography
Section for explanation of feather tracts.
The surveys were done at resting
and preening 3cy sub-adults (with at least no white mirror at P10
and at least some obvious second summer feathers).
michahellis primary moult scores: Boulogne-sur-Mer,
NW France, September & October 2001 & 2002.
3cy birds selected on bare part coloration, tail pattern,
pattern on inner secondaries and outer greater primary
coverts. Scores of longest fully grown new third generation
6699: L. michahellis 3cy, October 1 2001, Le Portel, France (50.43N-01.37E).