|
|||
| Coordinator: Greg Neubauer Marcin Przymencki Albert de Jong Mars Muusse cachinnans plumages |
From the Rarities Committee's files - Identification of Caspian Gull. Part 2: phenotypic variability and the field characteristics of hybrids, by Chris Gibbins, Grzegorz Neubauer and Brian Small, IN: BB 104/2011. Table 3. Percentages of sample adult birds with scores for selected plumage, structural and bare-part traits. |
||
| 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) | ||
| 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 | ||
Larus cachinnans