Herring Gull- Zilvermeeuw (argentatus & argenteus)

(last update: 3-1-2007)


Herring Gull plumages:

hg 1cy July
hg 1cy August
hg 1cy September
hg 1cy October
hg 1cy November
hg 1cy December

hg 2cy January
hg 2cy February
hg 2cy March
hg 2cy April
hg 2cy May
hg 2cy June
hg 2cy July
hg 2cy August
hg 2cy September
hg 2cy October
hg 2cy November
hg 2cy December

hg 3cy January
hg 3cy February
hg 3cy March
hg 3cy April
hg 3cy May
hg 3cy June
hg 3cy July
hg 3cy August
hg 3cy September
hg 3cy October
hg 3cy November
hg 3cy December

hg sub-ad January
hg sub-ad February
hg sub-ad March
hg sub-ad April
hg sub-ad May
hg sub-ad June
hg sub-ad July
hg sub-ad August
hg sub-ad September
hg sub-ad October
hg sub-ad November
hg sub-ad December

hg ad January
hg ad February
hg ad March
hg ad April
hg ad May
hg ad June
hg ad July
hg ad August
hg ad September
hg ad October
hg ad November
hg ad December

(2 images) Herring Gull 2cy (argentatus), July 14 2003, Tampere, Finland (61.31N, 23.43E).

A 2cy argentatus, showing vermiculated patterns on second generation wing-coverts. In many respects an average moult score for mid-July at Tampere. The complete moult is halfway with most wing-coverts and the inner primaries moulted to second generation. Primary P8 has been dropped and P9-P10 are still juvenile. P1-P6 are fully grown second generation flight-feathers; P6 just exceeds P5 in the folded wing. Now the central greater coverts are dropped, the juvenile secondaries underneath are exposed.
Many tertials and wing-coverts are replaced for second generation feathers. The upper tertials have been replaced and the lower tertials are still juvenile. The gap in the central greater coverts is almost closed; the new greater coverts grown in descendant order, from the outer-wing inwards, as is the common sequence and the gap is closed at about greater covert #6-8. Juvenile wing-coverts are still present in the upper row of lesser coverts. The fresh upper scapulars, which are probably third generation, look very second generation like.

By July, the warm brown tones of the first moulted second generation feathers (inner greater coverts and inner median coverts) are faded to plain white, leaving a contrasting barred pattern on the wing-coverts. On average, 2cy argentatus is more contrastingly patterned than same aged 2cy argenteus, especially regarding the pattern on the central greater coverts. However, some argentatus are distinct "washed out" brown, showing the common vermiculated pattern of 2cy argenteus
The last moulted coverts are the central greater coverts and outer lesser coverts, replaced by mid-August. From mid-August onwards, 2cy argentatus start the partial autumn moult, starting again to drop the upper tertial and inner greater and median coverts. 

In the tables below, the primary moult scores of 2cy July argentatus in Finland can be read:

Primary moult score of 2cy argentatus Herring Gull, at Tampere landfill, Finland (61.33N, 23.59E) on July 10 2003.
. P4 fg P5 fg P6 fg P7 fg ? fg n:
P6-P10 - - - - - -
P7-P10 5 4 - - 6 15
P8-P10 1 54 6 - 13 74
P9-P10 - 11 34 - 2 47
P10 old - - 1 1 - 2
n: 6 69 41 1 21 138
n = 138; m old P = 2.7; SD old P = 0.67.
Survey at Tampere, landfill, in resting group at 'the saddle', about 200 2cy Herring Gulls, probably 100% argentatus.
P6-P10 = P6-P10 are still old and present.
? fg = fully grown not known. Fully grown primary score most probably P6 or less.
fg = fully grown. In our field surveys, a primary is 'fully grown' when it exceeds the previous feather in the folded wing. Actually,  such 'fully grown' feathers may have to grow a little, but under field circumstances, it's very difficult to find out if the waxy sheath, which is the standard measurement for fully grown primaries, is still present. 


Primary moult score of 2cy argentatus Herring Gull, at Tampere landfill, Finland (61.33N, 23.59E) on July 13 2003, 15:00 h.
. P4 fg P5 fg P6 fg P7 fg ? fg n:
P6-P10 - - - - 1 1
P7-P10 2 - - - 4 6
P8-P10 - 26 6 - 18 50
P9-P10 - 20 52 1 5 78
P10 old - - 5 3 - 8
n: 2 46 63 4 28 143
n = 143; m old P = 2.4; SD old P = 0.69.
Survey at Tampere, landfill, in resting group at 'Bio I'.