Gulls in NW Europe

(last update: September 25, 2011 )

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argentatus / argenteus

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Herring Gull (argenteus) BLB H-66866 4CY-19CY, October 2003, January 2011 & August-September 2018, Brouwersdam, the Netherlands.

Ringed as 2cy on 16 May 2001 at Oostende Beach, Belgium. Behaviour indicates male.

History:

below: 4cy BLB H-66866 October 11 2003, Brouwersdam, the Netherlands.

A 4cy argenteus ringed in Belgium: Bruxelles H-66866. Ringed as 2cy bird on May 16 2001 at Oostende, Belgium (51.14N 02.53E). Not ringed as pullus, so not necessarily of local argenteus population, but in many respects argenteus, not argentatus. P5 has a black sub-terminal band on both inner-web and outer-web. This bird resembles an adult argenteus in many respect, but the black markings on the bill are too extensive for full adult birds. Note the pink-based bill, dark orbital ring and the relative dense streaking on the head. The primary moult score: P8 almost fully grown. 

From June (often mid-May in France, Belgium and the Netherlands) to October, a complete moult will bring birds in so-called "sub-adult winter" plumage. A new set of primaries will grow during the summer months and by October, the old primaries are all shed in argenteus in the Netherlands and northern France. In most adults (!), the new primary P6 is just visible beneath the tertials and shows a clear sub-terminal band. By late-October, P7 and P8 are fully-grown as well. At the same time, the wing-coverts have been renewed (note that the moult gap in central greater coverts is just closing in H-66866). In summer, the head is still largely white, but by September, most birds develop extensive 'winter streaking', in sub-adults strongly mottled brown contrasting with the white breast as in an executioner's hood. The tertials show obvious white tips. The iris is white-yellow with extensive speckling. The bill has a red gonydeal spot confined to the lower mandible. The orbital ring is yellow-orange in most argenteus, but often dark in autumn.

below: 12cy BLB H-66866 January 06 2011, Brouwersdam, the Netherlands.

Note black on bill and sharp black spot on P5.

below: 17cy BLB H-66866 August 14 2016, Brouwersdam, the Netherlands.

below: Herring Gull argenteus BLB H-66866 17CY, September 30 2016, Brouwersdam, the Netherlands.

P6/P9. Head moulted recently.

below: 19cy BLB H-66866 September 18 2018, Brouwersdam, the Netherlands.

P7/P10.