Herring Gull - Zilvermeeuw (argentatus & argenteus)

(last update: 08 december 2003)

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Herring Gull adult (argentatus), January 06 1992, Worcestershire, Britain. Picture by Peter Stewart.

Adult birds from the western populations argenteus show more black in the outer primaries, compared to northern argentatus. In argenteus, P5 normally shows small black sub-terminal markings, concentrated on the outer-web as a clear-cut black angular spot and in some birds extending on the inner-web as a diffuse streak. There may be some black on P4 as well, although this might be a clue for near-adult birds. In argentatus, especially from far northern Scandinavia, the black marking on P5 is completely lacking or is very limited and diffuse.
Argenteus
often has a black sub-terminal band on the top of P10, dividing the tip from the mirror. If the black sub-terminal band on P10 is broken, there is often still black on the inner and outer-web's edge of P10. Normally argentatus lacks sub-terminal markings on the outer-web of P10.
In adult Herring Gull, the scapular coverts are plain grey, lacking white crescents. The tertials show obvious white tips. The iris is yellow. The bill is yellow with a red gonydeal spot, confined to the lower mandible. The orbital ring is yellowish or yellow-orange in argenteus; slightly orange-red or coral red in most argentatus; especially birds from the Baltic region show a bias to reddish orbital rings. The legs are flesh-pink in argenteus, but may show a yellowish hue or appear very clear yellow in some argentatus (from either the Baltic region or far northern Finnmark). Furthermore, adult argentatus from Finnmark also seem to develop "bubble-gum" pink legs. 

This bird and the one in the previous photograph were both caught with those of the 06.01.1992. Note the different wing-tip patterns. An extensive research about primary-tip pattern was done by the late E.K. Barth in the sixties. Results are represented in the table below.

Table 4 from E.K. Barth, The circumpolar systematics of Larus argentatus and Larus fuscus with special reference to the Norwegian populations, 1968. 200 Norwegian birds. (Notation converted to what we use in the texts, MM).
locality sample size tip pattern P10 tip pattern P9 colour of P10 inner-web black present from P10 to:
1 2 3 4 1 2 3 4 5 1 2 3 5 6 P7 P6 P5 P4
East Finnmark 15 n 10 1 2 2 5 4 1 1 4 5 7 3 12 3 - 10 5 -
% 67 7 13 13 33 27 7 7 27 33 47 20 80 20 - 67 33 -
Tamsöy in Central Finnmark 33 n 17 7 6 3 10 10 6 0 7 12 20 1 23 10 - 19 13 1
% 52 21 18 9 30 30 18 - 21 36 61 3 70 30 - 58 39 -
Troms 29 n 17 8 3 1 11 9 4 1 4 3 20 6 24 5 - 24 5 -
% 59 28 10 3 38 31 14 3 14 10 69 21 83 17 - 83 17 -
Bodö and Röst 32 n 15 10 3 2 19 3 5 0 3 3 24 5 27 5 1 18 13 -
% 50 33 10 7 63 10 17 - 10 9 75 16 84 16 3 56 41 -
Tarva 20 n 8 7 3 2 11 5 4 0 0 10 8 2 12 8 1 7 10 2
% 40 35 15 10 55 25 20 - - 50 40 10 60 40 5 35 50 10
Stavanger and Lindesnes 42 n 18 13 4 6 23 12 3 2 2 15 23 4 37 5 - 13 29 -
% 44 32 10 14 55 28 7 5 5 36 55 9 88 12 - 31 69 -
Oslo Fiord 29 n 19 6 3 1 20 1 4 1 2 12 14 3 24 5 - 17 12 -
% 66 21 10 3 71 4 14 4 7 42 48 10 83 17 - 59 41 -
1: all white
2: trace of black near tip
3: incomplete black bar near tip
4: complete black bar or black tip
1: broad white band over both webs
2: white spot on both webs
3: white spot on inner web only
4: no white spot present
5: 'thayeri-pattern'
1: like mantle colour
2: slightly lighter than mantle colour
3: markedly lighter than mantle colour
5: relatively sharp border between black and grey
6: gradual transition from black to grey