Larus cachinnans
(last update:
Greg Neubauer
Marcin Przymencki
Albert de Jong
Mars Muusse
cachinnans plumages
Larus cachinnans hybrid 5CY-6CY female PLG DN-19273 October 2009 & Jul;y 2010, Deponie Pohlsche Heide - Minden, Germany (52°23'05N, 08°46'45E). Picture: Armin Deutsch.
5CY Female F2 hybrid Caspian x Herring Gull, Pohlsche Heide, Germany, October 06 2009. Parentage confirmed by microsatellite markers. Both parents were hybrids, trapped at the nest and identified in the hand by phenotype; the female parent had an intermediate genotype. Ringed as a chick in Wloclawek, central Poland, May 11 2005. Unlikely to be separated from Herring Gull with confidence, while pure Caspian can be excluded on the basis of the P10 pattern (very short tongue), the head shape and facial expression (notably the very pale eye). However, signs of Caspian genes include the longish legs, relatively slim bill and nearly all-white head, despite the fact that the moult to winter plumage is more or less finished. Despite it not being possible to calculate a total score for this bird (P4 and P5 patterns not visible), it must have been higher than 12 (this was the partial score without inclusion of P4 and P5). This score reflects the bird’s similarity to Herring (see fig. 6).
To discuss such birds, its good to first classify it on the 'hybrid scale' according Gibbins et al, see table below pictures.
below: cachinnans hybrid 5CY female PLG DN-19273 October 06 2009, Deponie Pohlsche Heide - Minden, Germany (52°23'05N, 08°46'45E). Picture: Armin Deutsch.
below: cachinnans hybrid 5CY female PLG DN-19273 October 22 2009, Deponie Pohlsche Heide - Minden, Germany (52°23'05N, 08°46'45E). Picture: Armin Deutsch.
below: cachinnans hybrid 6CY female PLG DN-19273 July 29 2010, Deponie Pohlsche Heide - Minden, Germany (52°23'05N, 08°46'45E). Picture: Armin Deutsch.
Still showing a broad medial band (black band separating mirror from pale innerweb on P10), which is not good for cachinnans (in cachinnans medial band preferably thinner than mirror width). Note clean yellow staring eye.
below: together with Larus michahellis (right).
Below, table 1 is repeated to score this bird. Not all traits can be scored, the partial scores are in italic + bold.
Total score is 14 (by Mars Muusse). The caption with this image mentions a partial score of 12 on 7 traits (pattern on P4 and P5 not included), leaving room for discussion on how to score characters here from the images; e.g. should such legs be scored "moderately long" or "long" and, from what we see of the P10 tongue, should it be scored "same shade as mantle" or "paler than mantle"? And is the eye ring colour paler orange? If so, these trait scores would sum to the current score, raising it eventually to 16.
| Trait | Score | Description |
| P10 overall pattern: white to black ratio | 0 | less black than white |
| 1 | approximately equal black and white | |
| 2 | more black than white | |
| P10: white tip | 0 | clear white, no signs of black |
| 1 | small dark spots on one or both webs | |
| 2 | incomplete subterminal bar (two large black spots, one on each web or an unconnected bar, broken in the middle) | |
| 3 | complete subterminal bar | |
| P10: tongue | 0 | white or whitish |
| 1 | paler than mantle | |
| 2 | same shade as mantle | |
| P5: extent of black | 0 | black on both webs connected, forming band, black of equal depth on each web |
| 1 | black on both webs connected, forming band, black on outer web deeper than inner | |
| 2 | black on both webs, but isolated spots (= incomplete bar) | |
| 3 | black on outer web only | |
| 4 | no black | |
| P4: extent of black | 0 | black on both webs |
| 1 | black on one web only | |
| 2 | no black | |
| Iris peppering | 0 | dark-looking, >50% covered by dark spotting/peppering |
| 1 | moderately dark, with 10-50% of the area spotted | |
| 2 | single or very few dark spots (area < 10%) | |
| 3 | no dark spotting on iris | |
| Eye-ring colour | 0 | dark/deep orange to red |
| 1 | pale to moderately orange | |
| 2 | yellow | |
| Bill shape | 0 | very long and slim, with little/no visible gonydeal angle (L:D ratio >2.8) |
| 1 | slim, slight gonydeal angle (ratio 2.4-2.79) measured 2,65 Mars Muusse | |
| 2 | intermediate (ratio 2.0-2.39) | |
| 3 | short and deep, well-marked gonydeal angle (ratio <2.0) | |
| Leg length | 0 | long |
| 1 | moderately long | |
| 2 | short |