American Herring Gull (smithsonianus)
(last update: October 30, 2015)
American Herring Gull (smithsonianus) adult.
P6 (figure 9)
The shape of the black mark is important. The black band was always complete in our sample of NF smithsonianus (in some birds of European forms, especially in argentatus, there is sometimes only an incomplete black band), and the pattern was usually sharply pointed. It is pointed along the inner edge, along the shaft, and along the outer edge, so that the pattern tends to resemble a sort of drawn out ’W’ (see figure 9a and percentages below it). In quite a few European birds, the black band is clearly broader, lacking the three pointed wedges, and showing an oblique, rounded or straight upper border on the outer web (figure 9b and 9c).
|
|||
| % NF smithsonianus | 95.0 |
4.4 |
0.6 |
| % argenteus | 62.5 |
8.6 |
29.1 |
| % argentatus | 55.6 |
33.3 |
11.1 |
| % E-Baltic Herring Gull | 51.3 |
35.1 |
13.5 |
FIGURE 9 Variation in pattern of P6 in herring gulls (Peter Adriaens). Percentages refer to the shape of the black pattern. Here, for instance, it is stated that 95% in our sample of NF smithsonianus showed a rather drawn-out 'W-pattern', being sharply pointed along the outer edge and the shaft, as illustrated in figure 9a. (click on image for larger view) |
|||
