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 90A34157 2cy (argentatus), July 16 2003, Tampere, Finland (61.31N, 23.43E).

A 2cy argentatus, ringed in Sweden 90A34157. Ringed as 2cy on 8 April 2003 at Malmö, Pildammsparken, Sweden (55.35N 13.00E), so no certain origin. The complete moult is well underway with most wing-coverts and the inner primaries moulted to second generation. Primary P7 has been dropped and P8-P10 are still juvenile. P1-P4 are fully grown second generation flight-feathers. All tail-feathers are still present.
Most tertials and the wing-coverts are replaced for second generation feathers. The three upper tertials have been replaced and the lower tertials are still juvenile. One inner greater covert is still juvenile (probably #5), while the central greater coverts are missing. The new greater coverts grown in descendant order, from the outer-wing inwards, as is the common sequence. The gap in the median covert row is just closed, with the last replaced feathers still buffish tinged. Most juvenile wing-coverts can be found in the upper row of lesser coverts. 
Fresh scapulars can be found in the rear lowest scapulars (probably moulted to second generation as these are the last in line in the common scapular moult sequence) and in the upper scapulars (probably replaced for third generation feathers). Again, the fresh upper scapulars look very second generation like. The fresh scapulars strongly contrast with the adjacent old abraded second generation feathers, not as much in pattern but in wear and tear.

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'.