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This
website deals with the Yellow-legged Gull taxon michahellis, which
is a common migrant from July to December in NW Europe. After extensive expansion
of the breeding population during the last three decades, it nowadays can
be found breeding in Belgium, the Netherlands and Britain in mixed couples
with both Herring Gull (argenteus) and Lesser Black-backed Gull (graellsii).
There are subtle differences between the populations from the
Mediterranean, Atlantic coast of Portugal and Morocco and from the islands
in the Atlantic. Most pronounced differences can be found in the taxon atlantis,
now regarded as full species by some authors.
General
description:
By November, 2cy michahellis show
an almost similar plumage as 2cy
October birds. There is hardly any additional moult in
November and the main differences can be found in the state of wear of the
feathers. Wing-coverts included in the partial moult start to show slight
wear in the fringes as well by November.
Moult stage and
pace of remiges and rectrices:
All 2cy michahellis
have finished the complete moult in the primaries, secondaries and
rectrices by early-October. By
the winter months, moult in the rectrices may be seen again in few 2cy michahellis. Birds grow in plain white
tail-feathers or white feathers with limited black vermiculation. Active
moult in the tail-feathers can also be seen in 3cy michahellis in
partial spring moult (May).
Timing and
strategy of partial moult
The complete moult take all the
summer months, in which 2cy michahellis moult all the
scapulars, wing-coverts, tertials and flight-feathers. In the July and
August
sections the progress of this complete moult is described.
From late-August, the
complete moult in the wing-coverts finishes 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 for second
generation feathers, the partial autumn moult starts in 2cy michahellis,
starting again
with the upper tertials and outer median coverts.
By early-November, this partial moult finishes.
In most individuals, the moult strategy in the partial moult follows a common
strategy: 2cy michahellis start
the partial moult with shedding the outermost median coverts, followed by
the upper tertials. This moult stage can be found commonly in late August
(see e.g. image 05 in the
August section) but may be found in late September birds as well (image
4733). Most extensive replacement takes place in the median and
lower lesser coverts in October (see e.g. image
6630). Moult in the greater coverts is often confined
to the inner feathers and moult in the tertials is often confined to
the upper three feathers. 2cy michahellis hardly replace
lesser coverts, and if they do, there is no distinguishable
sequence.
It's hard to label the feathers to exact
generation. As can be seen in the 1cy michahellis October section, the post-juvenile moult in michahellis can be very
extensive. Most michahellis moult inner wing-coverts to second
generation in 1cy October. They replace these wing-coverts again in
the complete moult in July-August. Then again, inner wing-coverts
are replaced by the partial moult in 2cy michahellis in
September, but not necessarily the same wing-coverts as in the
post-juvenile moult.
Moult stage and
pace of scapulars:
By November, scapular moult
continues at very low pace. Due to the
considerable moult in the scapulars in 1cy birds in August, in 2cy birds in
April-May, in July and again in September, we exclude the scapulars from
further analysis.
Movements
By November, only few 2cy
michahellis can be found along the coasts of SW Netherlands and NW
France. The majority returns to lower latitudes. Those which remain,
probably belong to michahellis
from the colonies of Marseille and
the Mediterranean coast.
Tables
No tables.
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michahellis
2cy ITB CH3160 November
05 2010, Westkapelle, the Netherlands. |
michahellis 2cy HES M010408 November
09 2008, Westkapelle, the Netherlands. |
michahellis 2cy HES M013277 November
05 2010, Westkapelle, the Netherlands. |
michahellis 2cy 322J, November
27 2003, Port-la-Nouvelle, S France (43°00'N - 3°04'E). |
michahellis
2cy 664H, November
27 2003, Port-la-Nouvelle, S France (43°00'N - 3°04'E). |
michahellis
2cy 063J, November
27 2003, Port-la-Nouvelle, S France (43°00'N - 3°04'E). |
michahellis
2cy 295Z, November
25 2003, Sète, S France (43°24'N - 03°42'E). Photo
Ruud Altenburg. |
michahellis
2cy NY4Y, November
25 2003, Montpellier, S France. Photo
Ruud Altenburg. |
michahellis
2cy 37Z, November
12 2003, Maastricht, the Netherlands. Photo Rik Winters. |
michahellis 29Y 2cy November 09 2008, Westkapelle, the Netherlands. Picture: Pim Wolf.. |
YLG (L. michahellis) 2cy, November 24-26 2006, Etaples / Boulogne-sur-Mer, NW France. |
YLG (L. michahellis) 2cy, November 24-26 2006, Etaples / Boulogne-sur-Mer, NW France. |
YLG (L. michahellis) 2cy, November 24-26 2006, Etaples / Boulogne-sur-Mer, NW France. |
YLG (L. michahellis) 2cy, November 24-26 2006, Etaples / Boulogne-sur-Mer, NW France. |
michahellis
2cy, November 16 2002, Westkapelle, the Netherlands (51.33N 03.25E). |
michahellis
2cy, November 15 2003, Westkapelle, the Netherlands (51.33N 03.25E). |
michahellis
2cy, November 15 2003, Westkapelle, the Netherlands (51.33N 03.25E). |
michahellis
2cy, November 23 2003, Rosas, NE Spain.
Classical 2cy. |
michahellis
2cy, November 23 2003, Rosas, NE Spain. Delayed looking
bird. |
michahellis
2cy, November 23 2003, Rosas, NE Spain. Advanced looking
bird. |
michahellis
2cy, November 23 2003, Rosas, NE Spain.
Classical 2cy. |
michahellis
2cy, November 24 2003, Sète, S France (43°24'N - 03°42'E). Advanced
looking bird. |
michahellis
2cy, November 24 2003, Sète, S France (43°24'N - 03°42'E). Advanced
looking bird. |
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