Yellow-legged
Gull - Larus michahellis
(last update: October 08 2013)
Coordinators:
Delfín González
Gabriel Martín
Antonio Gutierrez
Amir Ben Dov
Mars Muusse
Larus michahellis - 3CY May
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 and birds along the Atlantic coast of the Iberian peninsular: lusitanius. Both atlantis and lusitanius are treated in their own sections on this website.
General description
By May the numbers of 3CY michahellis slightly increase at Etaples in NW France with a few 10's in total (Etaples,
Dannes, Boulogne-sur-Mer, see the Le
Portel Page). Probably, many 3CY birds frequent the future
breeding sites already and only return at Etaples from late June onwards.
The general appearance of May 3CY michahellis is rather
straightforward. Most birds are easily recognized between 3CY argenteus, with
darker grey upper-parts, pitch black primaries, with a red orbital
ring and of course with yellow legs. An example of the average michahellis can be found in the this image.
Moult stage and pace of remiges and rectrices
By mid-May, primary moult is just starting in 3CY birds, which are about two primaries behind compared to 2CY birds (with P3 and P4 missing by mid-May). The outer primaries and secondaries are second generation, replaced about half a year ago, the white crescents are worn away. The rectrices have the white tips worn way as well. By May, the partial spring moult has finished, and a small minority of 3CY michahellis have included some rectrices in this moult. Hence, it's not uncommon to find 3CY birds showing plain white tail-feathers, in some birds creating a 'blocked' tail pattern.
Timing and strategy of wing-covert moult in May
What's the average moult in May? We didn't
described enough 3CY birds in detail to draw any conclusions, the sample
size has been too small. A few preliminary conclusions:
Head-streaking, which was
obvious during the winter months and concentrated on the ear-coverts, around the eye and up to the
crown from September to March, has been replaced by snow-white fresh head-feathers.
The head and under-parts are white by May.
3CY birds show a combination of adult-like grey scapulars, contrasting with adjacent barred lesser coverts. By May, moult in the scapulars is near zero in 3CY michahellis. In some individuals, the scapular region contains some old and abraded feathers, sometimes showing a barred pattern, others are completely bleached white with only a slightly darker shaft-streak. However, most birds have the entire back adult-like grey.
In several sections of 1CY
and 2CY michahellis it's mentioned that birds include wing-coverts
in the post-juvenile moult (unlike argentatus / argenteus where this post-juvenile moult is confined to the scapulars). Wing-coverts
are replaced again in the compelte moult in 2CY and inner wing-coverts are
included in the partial moult in autumn in 2CY. In 3CY
birds, the wing-coverts are predominantly second generation, especially
the outer greater coverts and most of the lesser coverts (in the carpal edge).
Especially the median and lower lesser tract contain a mix of third or even fourth generation
wing-coverts.
The upper tertials are often included in the post-juvenile moult and the
partial autumn moult of 2CY as well. Some of the tertials, like the inner median and inner lower
lesser coverts, may appear adult-like, sometimes plain grey. However,
these grey third and fourth generation tertials may still show a delicate
diffuse brown pattern.
As stated earlier, the complete moult starts by mid-May, with 3CY birds dropping the innermost primary P1. Subsequently, the outer median coverts are shed as well as a start of the complete moult in the wing-coverts. This is the moult stage by the end of the month.
See Topography Section for explanation of feather tracts.
Movements
By May, only the number of 3CY michahellis along the coasts of NW France increases slightly, as 3CY michahellis probably prefer this area to undergo the complete moult. At Etaples' fish-market, there is plenty of food. They probably belong to michahellis from the colonies of Marseille and the Mediterranean coast.
Tables
No tables.
Yellow-legged Gull michahellis 3CY S8X8 May 24 2011, Delitzsch, Nordsachsen, Germany (51.30 N 12.19 E).
Picture: Jürgen Steudtner.
Yellow-legged
Gull michahellis HES M015862 1CY & 3CY, September 2006 & May 2008, Vijfhoek-Diemen, the Netherlands.
Yellow-legged
Gull michahellis 3CY, May 25 2013, Toulouse, France. Picture: Jean Joachim.
Yellow-legged
Gull michahellis 3CY, May 23 2012, Sant Carles de la Rapita - Ebro Delta, Cataluna, Spain. Picture: Chris Gibbins. AE4F8374 Tel Aviv University Zoological Garden 24.5.11.jpg)
Yellow-legged
Gull michahellis male, May 24 2011, Tel Aviv - University Garden, Israel. Picture: Amir Ben Dov. Breeding.
Yellow-legged Gull lusitanius 3CY, May 21 2006, Ribeira, Galicia, Spain. Photo: Ies Manuel García Barros.
Yellow-legged
Gull michahellis 3CY, May 17 2002, Boulogne/Mer France.Yellow legs, clear
yellow bill and many grey scapulars. Note the red orbital ring.
Yellow-legged
Gull michahellis 3CY, May 04 2001, Le Portel France.Yellow legs, clear
yellow bill and many grey scapulars. In the median coverts, active moult
to grey adult-like feathers is in progress.
Yellow-legged
Gull michahellis 3CY, May 05
2001, Etaples France.Note the
deep brown coloured centres of the old second generation outer
greater coverts.
Yellow-legged
Gull michahellis 3CY, May
17 2002, Boulogne/Mer France.The scapulars are completely
grey.