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 June

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 and by June, several 100's can be found in the region (Etaples, Dannes, Boulogne-sur-Mer, see theLe Portel Page).
The general appearance of 3CY michahellis is rather straightforward. Most birds are easily recognized between 3CY argenteus, with darker grey upper-parts, pitch black primaries and adult-like bare parts coloration: a red orbital ring and yellow legs. An example of the average michahellis can be found in the first image, an individual ringed near Marseille, S France, showing some worn grey wing-coverts, moulted in the partial moult.


mixed group of michahellis at Etaples, including three 3CY birds, June 26 2003.

Moult stage and pace of remiges and rectrices

As stated earlier, the complete moult starts by mid-May, with 3CY birds dropping the innermost primary P1. By mid-June, the complete moult is in progress: the primary moult score is about 4.9-5.5. 3CY birds are about two primaries behind compared to 2CY birds (which have only P7-P10 old by mid-June). The outer primaries and secondaries are second generation, replaced about half a year ago, the white crescents are worn away. 
We didn't described enough 3CY birds in detail to draw firm conclusions. By mid-May, primary moult started in 3CY birds. The table below presents an extrapolation of figures of 2CY and 3CY. Based on moult scores from July, we estimate the primary moult score of 3CY michahellis.

The rectrices have the white tips worn way as well. By June, 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. The complete moult in the tail-feathers has not started yet by mid-June.

Timing and strategy of body & covert moult in June

We didn't described enough 3CY birds in detail to draw detailed conclusions, the sample size has been too small. A few preliminary conclusions on 3CY 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.
  • 3CY birds show a combination of adult-like grey scapulars, contrasting with adjacent barred lesser coverts. It's difficult to score missing feathers in the complete grey upper-parts, hence we have no scapular moult scores. In general, obvious moult gaps are lacking in June. 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). The median coverts and lower lesser tract contain a mix of third or even fourth generation wing-coverts.
    The complete moult has started, obvious in the primaries with moult score 4.9-5.5. As the inner two or three primaries are dropped, the moult in the wing-coverts starts as well. The ordinary moult strategy and sequence start in the outer median coverts, the inner medians and greater coverts, the upper tertial and the outer lower lesser coverts, as is illustrated in this individual.
  • 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.
    By mid-June 3CY michahellis include the upper tertial in the complete moult. 

See Topography Section for explanation of feather tracts.

Table

Primary moult score in 3CY Larus michahellis, Etaples, NW France on June 28 2003 (09:00 h, low tide).
. P2 fg P3 fg P4 fg P5 fg ? fg n:
P5-P10 1 - - - 6 7
P6-P10 - 3 - - 34 37
P7-P10 - 4 3 1 27 35
P8-P10 - - 1 2 2 5
n: 1 7 4 3 69 84
n = 84; m old P = 4.5; SD old P = 0.73.
Group: 3x 3CY michahellis not scored; total michahellis present: 300+.
P6-P10 = P6-P10 are still old and present.
? fg = fully grown not known. Often referring to sleeping birds with folded wings, so fully grown primary score most probably P6 or less.
fg = fully grown. In our field surveys, a primary is 'fully grown' when it exceeds the previous feather in the folded wing. Actually,  such 'fully grown' feathers may have to grow a little, but under field circumstances, it's very difficult to find out if the waxy sheath, which is the standard measurement for fully grown primaries, is still present. 
3CY identified on absence of P10 mirror & bare parts coloration.
adult michahellis in April. (61415 bytes)Yellow-legged Gull michahellis 3CY HES M002383 June 04 2007, Portalban, Switzerland. Picture: Stephane Aubry.
adult michahellis in April. (61415 bytes)Yellow-legged Gull michahellis 3CY HES M002690 June 30 2008, Gorgier, Switzerland. Picture: Stephane Aubry.
3cy michahellis in June, ringed in S France. (73694 bytes)Yellow-legged Gull michahellis 3CY 074S June 13 & 14 2002, Etaples, France. Ringed near Marseille, S France.
3cy michahellis in June, ringed in S France. (45496 bytes)Yellow-legged Gull michahellis 3CY 242T June 28 2003, Etaples, France. Ringed near Marseille, S France.
3cy michahellis in June, ringed in S France. (45617 bytes)Yellow-legged Gull michahellis 3CY 662D June 28 2003, Etaples, France. Ringed near Marseille, S France.
2cy michahellis in August, ringed in Switzerland.Yellow-legged Gull michahellis 3CY 74BH June 11 2012, Poreč landfill, Croatia. Picture: ringing team Luka Jurinovic.
2cy michahellis in August, ringed in Switzerland.Yellow-legged Gull michahellis 3CY S6YH June 02 2011, Szeged, Hungary. Picture: Csaba Barkóczi.
2cy michahellis in August, ringed in Switzerland.Yellow-legged Gull michahellis 3CY S345 June 17 2005, Budapest, Hungary. Picture: András Kóta.
2cy michahellis in August, ringed in Switzerland.Yellow-legged Gull lusitanius 3CY A:21V June 09 2013, Arteixo, A Coruña, Spain. Picture: Xabi Varela.
2cy michahellis in August, ringed in Switzerland.Yellow-legged Gull lusitanius 3CY ZR1S June 29 2013, Arteixo, A Coruña, Spain. Picture: Xabi Varela.
2cy michahellis in August, ringed in Switzerland.Yellow-legged Gull lusitanius 3CY ZR2S June & August 2013, Arteixo, A Coruña, Spain. Picture: Xabi Varela.
2cy michahellis in August, ringed in Switzerland.Yellow-legged Gull lusitanius 3CY ZR2W June & August 2013, Arteixo, A Coruña, Spain. Picture: Xabi Varela.
adult michahellis in April. (61415 bytes)Yellow-legged Gull michahellis 3CY, June 12 2006, Portalban, Switzerland. Picture: Stephane Aubry.
adult michahellis in April. (61415 bytes)Yellow-legged Gull michahellis 3CY, June 12 2006, Portalban, Switzerland. Picture: Stephane Aubry.
adult michahellis in April. (61415 bytes)Yellow-legged Gull michahellis 3CY, June 12 2006, Portalban, Switzerland. Picture: Stephane Aubry.
adult michahellis in April. (61415 bytes)Yellow-legged Gull michahellis 3CY, June 12 2006, Portalban, Switzerland. Picture: Stephane Aubry.
adult michahellis in April. (61415 bytes) Yellow-legged Gull michahellis 3CY, June 29 2013, Tel Aviv - University Zool. Garden, Israel. Picture: Amir Ben Dov.
adult michahellis in April. (61415 bytes) Yellow-legged Gull michahellis 3CY, June 10 2011, Tel Aviv - University Zool. Garden, Israel. Picture: Amir Ben Dov.
adult michahellis in April. (61415 bytes)Yellow-legged Gull michahellis 3CY, June 18 2011, Tel Aviv - University Garden, Israel. Picture: Amir Ben Dov.
2cy michahellis in August, ringed in Switzerland.Yellow-legged Gull michahellis 3CY, June 11 2012, Poreč landfill, Croatia. Picture: ringing team Luka Jurinovic.
2cy michahellis in August, ringed in Switzerland.Yellow-legged Gull michahellis 3CY, June 11 2012, Poreč landfill, Croatia. Picture: ringing team Luka Jurinovic.
3cy michahellis in June. (73325 bytes)Yellow-legged Gull michahellis 3CY, June 13 2002, Boulogne/Mer, France. Yellow legs, clear yellow bill and many grey scapulars. Note the red orbital ring.
3cy michahellis in June. (76071 bytes)Yellow-legged Gull michahellis 3CY, June 13 2002, Boulogne/Mer France. Yellow legs, clear yellow bill and many grey scapulars. Note the red orbital ring.
3cy michahellis in June. (84349 bytes)Yellow-legged Gull michahellis 3CY, June 14 2002, Boulogne/Mer, France. Yellow legs, clear yellow bill and many grey scapulars.
3cy michahellis in June. (27041 bytes)Yellow-legged Gull michahellis 3CY, June 26 2003, Etaples, France. One central tail-feather moulted recently.
3cy michahellis in June. (32187 bytes)Yellow-legged Gull michahellis 3CY, June 28 2003, Etaples, France. Tail complete old second generation.
3cy michahellis in June. (50470 bytes)Yellow-legged Gull michahellis 3CY, June 27 2003, Boulogne/Mer, France.
3cy michahellis in June. (56746 bytes)Yellow-legged Gull michahellis 3CY, June 28 2003, Etaples, France. Group of 3CY.
3cy michahellis in June. (33585 bytes)Yellow-legged Gull michahellis 3CY, June 28 2003, Etaples, France. Second generation secondaries.