Herring Gull- Zilvermeeuw (argentatus & argenteus)

(last update: 7-3-2007)


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 3cy ? (argentatus), July 13 2003, Tampere, Finland (61.31N, 23.43E).

A difficult bird, both in age and taxon. Maybe argentatus, but it in some respects it resembles cachinnans. The advanced grey upper-parts suggest 4cy, but the primaries and secondaries are more in line with 3cy. The small size suggesting a female. Age and taxon are difficult, but a few features are visible in the images.

Age probably 3cy:

  • Secondaries just visible in the central greater covert gap. They have extensive dark centres with the white tips almost completely worn away. In all respects, these secondaries resemble old second generation feathers, as is the case in 3cy July birds. In 4cy argentatus, the third generation secondaries may show dark markings, but this is often vermiculated at the tip, see e.g. a very immature 4cy ringed in Finland CA444. More often, the third generation secondaries are rather plain grey with white tips, see e.g. C68J1.
  • The tail-feathers show a broad sub-terminal band and many isolated dark markings at the base. This is the typical pattern in second generation rectrices, but very similar patterns can be found in third generation tail-feathers. See again CA444. However, the common pattern in third generation tail-feathers in 4cy (argenteus) are white feathers with only limited dark markings, see e.g. H-108929.
  • The old primaries are hardly bleached brown, still dark blackish without obvious mirror on P10. Both in the field and on the images, this mirror is absent. This is what can be expected in second generation primaries, although argentatus sometimes has no mirror on P10 in 4cy. 
    Another indication for 3cy is the high primary moult score for mid-July: P9-P10 still old and P5 fully grown. P6 is at half of the final length, at the length of P4. P5 has a complete sub-terminal band.
  • In the tables below, the primary moult scores of 3cy July argentatus in Finland can be read:
Primary moult score of 3cy argentatus Herring Gull, at Tampere landfill, Finland (61.33N, 23.59E) on July 13 2003, 15:00 h.
. P4 fg P5 fg P6 fg ? fg n:


- - - 1 1
P6-P10 - - - - -
P7-P10 2 1 - 8 11
P8-P10 1 40 3 25 69
P9-P10 - 1 9 - 10
n: 3 42 12 34 91
n = 91; m old P = 3.0; SD old P = 0.58.
Survey at Tampere, landfill, in resting group at 'Bio I'.

Taxon: some features point to cachinnans, but may still apply to argentatus as well:

  • complete white under-parts.
  • sloped forehead.
  • If age as 3cy is correct, it has very advanced grey upper-parts and wing-coverts compared to average 3cy argentatus.