Yellow-legged Gull - Larus michahellis

(last update: October 08 2013)

Delfín González
Gabriel Martín
Antonio Gutierrez
Amir Ben Dov
Mars Muusse

Yellow-legged Gull michahellis 2CY-4CY 074S July 2001 - June 2003, Etaples, NW France.

Ringed white right 074S in the Camarque (S France in 2000).

below: 074S michahellis 2CY, July 28 2001, Etaples, NW France.

Description: Tertials #1, 3-5 fully grown, #2 probably missing. Greater coverts #1-3 slightly bleached, #4 to the outer-wing fresher. Median coverts #1-11 pretty fresh (#7 growing), #12-14 missing, #15-19 2nd generation, #20 to outer-wing missing. Some lesser coverts missing and growing but lower lessers fully grown. Most scapulars 3rd generation, but at least 2 are 2nd generation and very abraded; no scapulars missing. Outer tail feathers (R5, R6) are growing (and are at 3/4 of the length). Mantle grey with brownish centre. 

P7 full-grown and p10 juvenile. 

Actively moulting secondaries: S1 full-grown, S2-3 growing and S4 to inner-wing missing, but there is a small block of 5 secondaries still present in the inner wing. 

below: 074S michahellis 3CY, June 14 2002, Etaples, NW France.

A 3CY michahellis showing pale pinkish legs, a clear yellow base of the bill, a rather dark iris, a red gonydeal spot (although obscured by the black bill-band) and complete grey upper-parts (mantle and scapular region). The orbital ring is obviously red. This bird was ringed near Marseille, S France, probably in year 2000. When data are available, more information will be added.
Most grey feathers in the wing-coverts are in better condition than the barred feathers, and apparently moulted later, i.e. in the partial autumn moult in 2CY (September-October). The inner greater coverts, the inner medians, a few lower lesser and some lesser coverts appear plain grey. The upper tertials are at least third generation as well, maybe even fourth generation, depending on the extend of the partial post-juvenile moult and the partial autumn moult as 2CY.

The tail is complete and all rectrices are second generation. The primary moult stage is P5 old, P4 missing. By mid-June, several 3CY michahellis were observed with primary moult score P3 missing / P4 old or with P4 missing / P5 old. Records in the surveys are too low to extract any conclusions, but 3CY birds are on average 1.5-1.8 primaries behind compared with 2CY birds. Extrapolation of figures can be read from the following table, with the conclusion that 3CY michahellis primary score will be at about 4.9-5.4 by mid-June.

extrapolated michahellis primary scores for June 3CY at Etaples. Complete tables can be found in the corresponding sections.
date June 13-14 July 10 2002 July 10 2002 July 27 2001 July 27 2001 July 28 2001 July 30 2001
2CY michahellis remaining primaries.  n = 41
m = 7.0
SD = 0.7
n = 48
m = 8.8
SD = 0.53
n = 45
m = 8.8
SD = 0.57
n = 51
m > 10.0*
n = 55 
m = 10.0
SD = 0.75
n = 51
m > 10.0*
2CY michahellis new primaries.    n = 45
m = 5.4
SD = 0.53
n = 42
m = 4.5
SD = 0.51
n = 51
m = 6.6
SD = 0.51
n = 55
m = 6.4
SD = 0.50
n = 51
m = 6.4
SD = 0.45
3CY michahellis remaining primaries. m = 4.9-5.4   n = 33
m = 7.0
SD = 0.61
      n = 92
m = 8.5
SD = 0.58
n: total number of observations
m: average score
SD: Standard Deviation
*: m > 10.0, i.e. the weighted average is beyond the number of remaining primaries.

Conclusion: Backwards extrapolation of 3CY moult scores would result in 5.4; Backwards extrapolation of remaining primaries of the relative differences between 2CY and 3CY birds would result in 4.9.

In the wing-coverts, active moult has been suspended in this individual. There are no moult gaps and the grey wing-coverts and tertials which were included in the partial moult are already slightly abraded.

below: 074S michahellis 3CY, September 21 2002, Etaples, NW France.

074S is another coloured bird, being almost all grey in the scapulars and wing-coverts as 3CY michahellis. Note the brown markings on the fourth tertial and the brownish wash on the outer greater coverts. The bill is obviously sub-adult, the legs are rather whitish yellow and the iris is very pale as well, slightly pigmented. Note also the small white tips on the outer primaries and P9 lacking a mirror.

below: 074S michahellis 4CY, June 28 2003, Etaples.

074S was seen again at Etaples by late June 2003. The primary moult score: P6-P10 still old. P1-P3 are fully grown (P3 obviously longer than P2 but an inch or so to grown). Dark primary coverts. The complete tail is present and plain white. Note the limited black markings on the bill and the brown abraded wing-coverts.