Moerdijk Field Research 2005-2006

(last update: 14 August 2010)

coordinators: 
Roland-Jan Buijs
Theo Muusse
Mars Muusse

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Introduction
Methods
Age, origin & sex
Retrapped Birds
Upperparts Greytone
Black on Primary Coverts
Black on Primaries
P10 and P9 Patterns
P5 Pattern
Red & Black on Bill
Iris & Orbital Ring
Primary Moult
Discussion
References

Larus argentatus argenteus & Larus fuscus graellsii - Moerdijk, the Netherlands

P10 and P9 Primary Patterns

Regarding the methods for P10 and P9 primary patterns classification: Following Goethe’s classification, we used six classes to characterise these feathers.
I: No mirror.
II: Mirror on one web.
III: Full sub-terminal black band, mirror on both webs.
IV: Sub-terminal black present, but band broken.
V: No sub-terminal black, mirror completely merged with tip.
VI: ‘Thayeri’ pattern, medial band not reaching the feather-edge of the inner web.
For more details, see plate 1 and Goethe (1961).

..I
II
III
IV V VI

In Herring Gull, the most frequent pattern in both sexes was a broken sub-terminal band on P10 (figure 2 and plate 1). The distribution of the P10 patterns did not differ significantly between sexes (Mann-Whitney U = 8441, Z = -1.593, P = 0.111, male n = 147, female n = 127).

Exactly half (50%) of the trapped Herring Gulls showed a complete sub-terminal band and a mirror covering both webs on P9. Again, there was no difference between the sexes in the distribution of P9 patterns (Mann-Whitney U = 9216, Z = -0.094, P = 0.925, male n = 146, female n = 127).

Twenty breeding birds were trapped in both 2005 and 2006. Of these retraps, 16 birds remained in the same P10 pattern category, one bird showed less black (m51) and one bird showed more black (m6P) in 2006. For P9, 12 birds remained in the same category, four birds showed less black (m2T, m4J, m46, mVE) and one bird showed more black (m51). Nog checken wat de Kalev Rattiste over larus canus vond

Three sub-adult birds (black on the primary coverts) showed no mirror on P10. When all sub-adult birds are excluded from the sample, the difference between sexes remains non-significant (P10: Mann-Whitney U = 7523, Z = -0.837, P = 0.403, male n = 129, female n = 123. P9: Mann-Whitney U = 7598, Z = -0.533, P = 0.594, male n = 128, female n = 123).

The vast majority (80%) of Lesser Black-backed Gull showed a complete sub-terminal black band across P10, with the mirror covering both the inner and outer web of the feather. For P9, there was no real dominant pattern (Figure 2). There is no significant difference between sexes for either the P10 or P9 patterns (P10: Mann-Whitney U = 106954, Z = -0.314, P = 0.754, male n = 433, female n = 498. P9: Mann-Whitney U = 103740, Z = -0.962, P = 0.336, male n = 433, female n = 496).

Forty-three Lesser Black-backed Gulls were caught in both 2005 and 2006. For P10, 35 birds remained in the same category, 3 birds showed less black and 1 bird (oNL) showed more black in 2006. Regarding P9 pattern, 32 retrapped birds remained in the same category, and 7 birds showed less black when retrapped in 2006.

Three sub-adult birds (with extensive black on the primary coverts) showed no mirror on P10. When all sub-adult birds (4cy and 5cy birds) are excluded, the difference between sexes remains non-significant (P10: Mann-Whitney U = 102672, Z = -0.015, P = 0.988, male n = 415, female n = 495. P9: Mann-Whitney U = 97749, Z = -1.309, P = 0.191, male n = 416, female n = 493).

Neither Herring nor Lesser Black-backed Gulls showed marked differences between the sexes in the sharpness of the division between the grey inner and black outer webs of P10. In Herring Gull about 56% shows a diffuse gradient on the underside of P10. In Lesser Black-backed Gull, 58% shows such a pattern on P10. This is in line with the findings of Barth (1975).

Figure 2: distribution of P10 and P9 patterns in Herring & Lesser Black-backed Gulls breeding at Moerdijk in 2005 & 2006.

Click HERE for larger pies / figure 2.

Read further on RESULTS: 5. P5 PRIMARY PATTERNS >

Lesser Black-backed Gull P10 pattern: I: No mirror. Herring Gull P10 pattern I: No mirror.
Lesser Black-backed Gull L.f. graellsii sub-adult 32, 06 May 2006. Herring Gull L.a. argenteus 4cy-5cy 6T, 21 May 2005 & 09 May 2006.
Lesser Black-backed Gull L.f. graellsii sub-adult HZ, 14 May 2006. Herring Gull L.a. argenteus 4cy E4, 02 May 2006.
Lesser Black-backed Gull L.f. graellsii sub-adult 1S, 16 May 2006.
Lesser Black-backed Gull P10 pattern II: Mirror on one web. Herring Gull P10 pattern II: Mirror on one web.
Lesser Black-backed Gull L.f. graellsii sub-adult PZ, 16 May 2006. No such birds in our sample.
Lesser Black-backed Gull L.f. graellsii sub-adult S9, 21 May 2006.
Lesser Black-backed Gull L.f. graellsii sub-adult TP, 21 May 2006.
Lesser Black-backed Gull P10 pattern III: Full sub-terminal black band, mirror on both webs. Herring Gull P10 pattern III: Full sub-terminal black band, mirror on both webs.
Lesser Black-backed Gull L.f. graellsii 12cy PB, 16 May 2006. Herring Gull L.a. argenteus 7cy 3E, 14 May 2005.
Lesser Black-backed Gull L.f. graellsii 13cy J3, 16 May 2005. Herring Gull L.a. argenteus 9cy 64, 21 May 2005.
Lesser Black-backed Gull L.f. graellsii 14cy ST, 21 May 2005. Herring Gull L.a. argenteus 24cy PL, 07 May 2006.
Lesser Black-backed Gull P10 pattern IV: Sub-terminal black present, but band broken. Herring Gull P10 pattern IV: Sub-terminal black present, but band broken.
Lesser Black-backed Gull L.f. graellsii sub-adult 20, 06 May 2006. Herring Gull L.a. argenteus 5cy HK, 04 May 2006.
Lesser Black-backed Gull L.f. graellsii 11cy K9, 16 May 2005. Herring Gull L.a. argenteus 9cy P3, 16 May 2005.
Lesser Black-backed Gull L.f. graellsii 13cy CK, 06 May 2005. Herring Gull L.a. argenteus 17cy 1A, 04 May 2005.
Lesser Black-backed Gull P10 pattern V: No sub-terminal black, mirror completely merged with tip. Herring Gull P10 pattern V: No sub-terminal black, mirror completely merged with tip.
Lesser Black-backed Gull L.f. graellsii 8cy VH, 08 May 2006. Herring Gull L.a. argenteus 8cy 2Z, 06 May 2005.
Lesser Black-backed Gull L.f. graellsii 8cy MA, 13 May 2006. Herring Gull L.a. argenteus 11cy H2, 05 May 2006.
Lesser Black-backed Gull L.f. graellsii adult 0V, 05 May 2005 & 09 May 2006. Herring Gull L.a. argenteus 11cy HL, 04 May 2006.
Lesser Black-backed Gull P10 pattern VI: 'Thayeri’ pattern, medial band not reaching the feather-edge of the inner web. Herring Gull P10 pattern VI: ‘Thayeri’ pattern, medial band not reaching the feather-edge of the inner web.
No such birds in our sample. Herring Gull L.a. argenteus HP, 05 May 2006.
Herring Gull L.a. argenteus 8cy NH, 16 May 2006.
Herring Gull L.a. argenteus NLA 5.363.004 12 July 2005.
Lesser Black-backed Gull P9 pattern I: No mirror. Herring Gull P9 pattern I: No mirror.
Lesser Black-backed Gull L.f. graellsii 10cy 67, 09 May 2006. Herring Gull L.a. argenteus 6cy 3T, 14 May 2005.
Lesser Black-backed Gull L.f. graellsii 11cy AZ, 05 May 2005. Herring Gull L.a. argenteus 7cy 3E, 14 May 2005.
Lesser Black-backed Gull L.f. graellsii 14cy UX, 15 May 2006. Herring Gull L.a. argenteus 11cy HL, 04 May 2006.
Lesser Black-backed Gull P9 pattern II: Mirror on one web. Herring Gull P9 pattern II: Mirror on one web.
Lesser Black-backed Gull L.f. graellsii 8cy E6, 04 May 2006. Herring Gull L.a. argenteus 5cy NU, 23 May 2006.
Lesser Black-backed Gull L.f. graellsii 13cy J3, 16 May 2005. Herring Gull L.a. argenteus 8cy 59, 21 May 2005.
Lesser Black-backed Gull L.f. graellsii 14cy C5, 08 May 2006. Herring Gull L.a. argenteus 19cy S0, 06 May 2005.
Lesser Black-backed Gull P9 pattern III: Full sub-terminal black band, mirror on both webs. Herring Gull P9 pattern III: Full sub-terminal black band, mirror on both webs.
Lesser Black-backed Gull L.f. graellsii 8cy 5A, 08 May 2006. Herring Gull L.a. argenteus 5cy HK, 04 May 2006.
Lesser Black-backed Gull L.f. graellsii 9cy TT, 21 May 2005. Herring Gull L.a. argenteus 11cy JK, 06 May 2006.
Lesser Black-backed Gull L.f. graellsii 12cy AF, 02 May 2006. Herring Gull L.a. argenteus 17cy 1A, 04 May 2005.
Lesser Black-backed Gull P9 pattern IV: Sub-terminal black present, but band broken. Herring Gull P9 pattern IV: Sub-terminal black present, but band broken.
Lesser Black-backed Gull L.f. graellsii 8cy VH, 08 May 2006. Herring Gull L.a. argenteus adult 60, 21 May 2005 & 16 May 2006.
Lesser Black-backed Gull L.f. graellsii 11cy K9, 16 May 2005. Herring Gull L.a. argenteus NN, 19 May 2006.
Lesser Black-backed Gull P9 pattern V: No sub-terminal black, mirror completely merged with tip. Herring Gull P9 pattern V: No sub-terminal black, mirror completely merged with tip.
No such birds in our sample. No such birds in our sample.
Lesser Black-backed Gull P9 pattern VI: Thayeri’ pattern, medial band not reaching the feather-edge of the inner web. Herring Gull P9 pattern VI: ȁThayeri’ pattern, medial band not reaching the feather-edge of the inner web.
No such birds in our sample. Herring Gull L.a. argenteus adult 1V, 05 May 2005.
Herring Gull L.a. argenteus adult 68, 21 May 2005.
Herring Gull L.a. argenteus NLA 5.363.004 12 July 2005.