Herring Gull- Zilvermeeuw (argentatus & argenteus)

(last update: 30-9-2009)


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

Herring Gull (argenteus) 1CY, November 19 2009, IJmuiden, the Netherlands. 

Local bird from IJmuiden showing extent of post-juvenile moult at start of the winter. After mid-November, the moult process may continue at very low pace, replacing single feathers in the scapular region, but in general the pictures doesn't change much anymore for the next 4 months, until February.

Elements of the old juvenile plumage are indicated in red; second generation feather tracs are pointed out by green lines.

Head and neck feathers replaced (1, 2) now with deeper, dark grey lines on pale ashy base. In these new feathers, the pattern is often still very clearly lined out, with spots very delicate and sharply edged lines, no blurry patterns and no bleached brown tones in new feathers.
Moult included the hindneck, but not all of the feathers, on the transition between neck and mantle a few old juvenile feathers clearly stand out (3).
Mantle feathers mostly replaced (4) and most scapulars replaced for 2nd gen feathers (5) with buffish tones and 'anchor pattern' (dark shaft streak and dark subterminal band). Single feathers in upper and lower scapular region still old juvenile (6), these are pale brown with worn fringes.
Herring Gull normally (95+% of the birds) show no post-juvenile moult (first basic moult) in wing-coverts, tertials and flight feathers. If any bird has replaced feathers in one of these tracts, it is worth checking the other side / other wing as well to look for symmatry, as single feathers may be replaced sometimes due to feather loss in fights over food, etc. However, some 1st cycle Herring Gulls may really moult several wing-coverts. The differences in patterns are often obvious in 1st cycle birds. For instance, the old juvenile tertials (7) have brown centra and notched fringes (white parts may be worn), and fresher, replaced 2nd gen tertials (8) normally contrast due to colour and pattern. This is also true for wing-coverts: old juvenile coverts have brown, bleached centres and the white notching worn away (12), while replaced feathers are new (11), often still showing a buffish tone and neat fringes and a pattern with delicate marbling. To confirm they really are 2nd generation feathers, simply compare the feather to adjacent feathers, and keep in mind that new wing-coverts grow in from two loci, the two waves meeting at about covert #6-8.
1st cycle Herring Gull doesn't include flight feathers in the post-juvenile moult: tail (9), secondaries and primaries (10) all remain juvenile feathers until the start of the complete moult in spring, when P1 will be dropped.
Like the head feathers, many of the body feathers as well are included in the post-juvenile moult. Again, colour and pattern between new 2nd gen feathers (13) and old juvenile body feathers (14) are different.

above: Herring Gull 1st cycle, November 19 2009.
below: Herring Gull 1st cycle, November 19 2009.

Herring Gull from northern argentatus populations often have more limited moult than Dutch argenteus. Below, DEH 4304457, ringed in Germany. Overall in juvenile plumage (wing-coverts, tertials, rectrices, seconadries, primaries), but some upper scapulars replaced (2), head feathers with fine streaking (1) and in neck and on side of breast and flanks note the grey based feathers (4) between old brown feathers (5).