Yellow-legged
Gull - Larus michahellis
(last update: October 08 2013)
Coordinators:
Delfín González
Gabriel Martín
Antonio Gutierrez
Amir Ben Dov
Mars Muusse
Larus michahellis - 4CY / sub-adult July
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 and 4CY michahellis slightly increase at Etaples in NW France and by June, several 100's can
be found in the region (Etaples, Dannes, Boulogne-sur-Mer, see the Le
Portel Page).
The general appearance of 4CY michahellis in June is rather
straightforward. All individuals still have P10 present, so show a white
mirror on the outermost primary. This is an easy clue for separating it
from 3CY birds. 4CY show adult-like primaries, but still the outer greater
primary coverts are dark, unlike full adult birds. An example of the
average 4CY michahellis can be found in the first image, an individual ringed near Marseille, S France, showing some worn
grey wing-coverts. The brown primary coverts are obvious in this bird.
Moult of remiges and rectrices 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 shown by most sub-adult michahellis by the end of June. The average bird may also shed outer lower lesser coverts and the upper tertial, when moult progresses (P5 shed).
The rectrices have the tips worn away and may even look very abraded in 4CY michahellis. By June, the partial spring moult has finished, and a small minority of 3CY michahellis included some rectrices in this moult. These birds show a 'blocked' tail pattern. Sub-adult birds may include tail feathers in the partial spring moult as well, but both generations are plain white and may only be recognized at short range when the state of wear can be established. The complete moult in the rectrices and secondaries have not started yet by late-June 4CY michahellis.
See Topography Section for explanation of feather tracts.
Timing and strategy of body & covert moult in June
We didn't described enough sub-adult birds in detail to draw detailed conclusions, the sample size has been too small. A few preliminary conclusions on 4CY michahellis:
- 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 and still white in June.
- 4CY birds show grey upper-parts, but there is a strong brown hue on the central greater coverts and worn inner lower lesser coverts.
- Some birds show moult in the head-feathers: "moth-eaten" appearance.
Tables
no tables.
Yellow-legged
Gull michahellis 074S sub-adult, Etaples, NW France, June
28 2003. Seen at the same spot one year ago as 3CY.
Yellow-legged
Gull michahellis 742D June
28 2003, Etaples, France.A 4CY bird ringed white 742D, ringed near Marseille, S France.
Yellow-legged Gull michahellis 4CY HES 895217 June 29 2005, Chablais de Cudrefin, Switzerland. Picture: Stephane Aubry.
Yellow-legged Gull michahellis 4CY HES M015536 June 04 2007, Portalban, Switzerland. Picture: Stephane Aubry.
Yellow-legged Gull michahellis 4CY 92BH June 11 2012, Poreč landfill, Croatia. Picture: ringing team Luka Jurinovic.
Yellow-legged
Gull michahellis sub-adult/5CY, June 12 2006, Chablais de Cudrefin, Switzerland. Picture: Stephane Aubry.
Yellow-legged Gull michahellis 4CY, June 12 2006, Chablais de Cudrefin, Switzerland. Picture: Stephane Aubry.
Yellow-legged Gull michahellis 4CY, June 12 2006, Chablais de Cudrefin, Switzerland. Picture: Stephane Aubry.
Yellow-legged Gull michahellis 4CY, June 22 2008, Italy. Picture: Marco.
Yellow-legged Gull michahellis sub-adult, June 25 2009, Gibraltar, UK. Picture: Francesco Montalbano.
Yellow-legged
Gull michahellis sub-adult, Etaples, NW France, June
26 2003.