See Cantabrican for details of cantabricans (Cantabrican Atlantic Yellow-legged Gull)
See argenteus (south west England) for details of argenteus (Herring Gulls of south west England)
|
Area |
P10 |
P9 |
P6-P10 |
P5 |
P4 |
|||||||||
|
|
S |
Tip (%) |
LM (%) |
SM (%) |
M (%) |
S |
Sol -id (%) |
SI (%) |
LI (%) |
S |
BB (%) |
TB (%) |
IM (%) |
PN (%) |
|
Devon argenteus |
22 |
32 |
68 |
0 |
90 |
23 |
0 |
30 |
70 |
23 |
0 |
26 |
74 |
0 |
|
Cantabrican |
27 |
73 |
27 |
0 |
85 |
28 |
0 |
30 |
70 |
16 |
6 |
63 |
31 |
10 |
See main statistics adults for explanation of terms.
Note: broad similarity in having much white in P9 and P10 and little black from P4-P8. The only major difference is between the proportions with complete white tip and large mirror on P10. Cantabrican birds appear to have slightly more black on P5 and P4.
Statistics for calls are also compared:
|
Area |
Long calls % like |
Mew calls % like |
|||||
|
|
graellsii |
Shrill graellsii |
argenteus/ Deep argenteus |
Medi-terranean michahellis |
graellsii |
argenteus |
Medi-terranean michahellis |
|
Devon argenteus |
0 |
0 |
100 |
0 |
0 |
100 |
0 |
|
Santander |
0 |
0 |
100 |
0 |
0 |
100 |
0 |
Note: similarity
Primary Moult in adult Devon argenteus:
|
20 July 1999 |
4 P3/P4; 2 P1/P2; 1 P4/P5 |
|
3 Aug 2001 |
3 P6/P7; 2 P5/P6 |
|
22 Oct 2001 |
3 P8/P9+P10; 5 P9/P10 |
|
20 Apr 2002 |
------ |
Primary Moult in adult Cantabrican:
|
1-9 August 1990 |
Most frequent P4/P5; range P3/P4-P5/P6 |
Statistics for Perched First-years are compared:
|
Area |
Month |
Mantle colour |
Mantle texture |
Bill colour |
Tertials |
||||||||||||
|
|
|
S |
RB |
RT |
GB |
S |
SC |
LC |
S |
BL |
PB |
S |
PF |
PT |
PC |
PN |
|
|
Devon argenteus |
April |
3 |
35 |
65 |
0 |
2 |
100 |
0 |
5 |
20 |
80 |
1 |
0 |
100 |
0 |
0 |
|
|
Devon argenteus |
August |
7 |
0 |
100 |
0 |
6 |
65 |
35 |
7 |
100 |
0 |
4 |
0 |
0 |
50 |
50 |
|
|
Devon argenteus |
October |
2 |
0 |
100 |
0 |
2 |
100 |
0 |
2 |
100 |
0 |
2 |
0 |
0 |
50 |
50 |
|
|
San Sebastian |
February |
8 |
25 |
50 |
25 |
2 |
100 |
0 |
9 |
65 |
35 |
2 |
100 |
0 |
0 |
0 |
|
|
Santander |
August |
16 |
25 |
60 |
15 |
8 |
55 |
45 |
5 |
20 |
80 |
1 |
0 |
0 |
100 |
0 |
|
See main statistics first-years for explanation of terms.
Note: similarity in mantle colour and texture (ruddy tinge and scaley); sample for tertials is small and there is much variation; colour of the bill base in both forms becomes paler with age, apparently particularly so for the Cantabrican form.
Statistics of First-years in Flight are compared:
|
Area |
Month |
Underwing Pattern |
Tail colour |
Inner wing |
Pale primary panel |
||||||||||
|
|
|
S |
UN |
CS |
CM |
S |
BR |
DL |
S |
2B |
1B |
S |
OB |
IN |
NO |
|
Devon argenteus |
April |
1 |
0 |
0 |
100 |
2 |
50 |
50 |
2 |
0 |
100 |
4 |
50 |
50 |
0 |
|
Devon argenteus |
August |
1 |
0 |
100 |
0 |
5 |
0 |
100 |
4 |
0 |
100 |
2 |
100 |
0 |
0 |
|
Devon argenteus |
October |
0 |
|
|
|
1 |
0 |
100 |
1 |
0 |
100 |
1 |
100 |
0 |
0 |
|
San Sebastian |
February |
4 |
0 |
100 |
0 |
6 |
15 |
85 |
6 |
15 |
85 |
8 |
50 |
50 |
0 |
|
Santander |
August |
0 |
|
|
|
1 |
100 |
0 |
2 |
0 |
100 |
2 |
50 |
50 |
0 |
Note: tails tend to be dusky until spring in both forms; also the inner wing in both forms normally has only one bar; the pale primary panel is obvious or indistinct in roughly equal proportions in both forms; the underwing sample sizes are small.
Statistics for Head and Body Streaking in First-years are compared:
|
Location |
Dates visited |
Juvenile/1st year Head markings |
Juvenile/1st year Breast markings |
Juvenile/1st year Belly markings |
||||||||
|
|
|
S |
dusky |
white |
S |
heavy |
sparse |
white |
S |
heavy |
sparse |
white |
|
Devon argenteus |
April |
5 |
40 |
60 |
5 |
40 |
60 |
0 |
2 |
0 |
100 |
0 |
|
Devon argenteus |
August |
7 |
100 |
0 |
6 |
100 |
0 |
0 |
6 |
100 |
0 |
0 |
|
Devon argenteus |
October |
2 |
100 |
0 |
2 |
100 |
0 |
0 |
2 |
100 |
0 |
0 |
|
San Sebastian |
February |
10 |
90 |
10 |
5 |
60 |
40 |
0 |
5 |
60 |
40 |
0 |
|
Santander |
1 - 9 Aug |
16 |
100 |
0 |
10 |
90 |
10 |
0 |
10 |
90 |
10 |
0 |
Note: heads are very dusky in both forms through the first winter; breast and belly markings are heavier in the Devon birds than in the Cantabrican ones.
Overall: a broad similarity looking at all of the above data. The Cantabrican Atlantic Yellow-legged Gull can be thought of fairly accurately as argenteus with yellow-legs. A darker mantle shade and slightly more lightweight appearance also seem to be distinctive characters of the Cantabrican form.